Adobe Photoshop

File Formats

Specification

October 2013

Copyright © 1991-2013 Adobe Systems Incorporated. All rights reserved.

Portions Copyright © 1990-1991, Thomas Knoll.

The information in this document is furnished for informational use only, is subject to change without notice, and should not be construed as a commitment by Adobe Systems Incorporated. Adobe Systems Incorporated assumes no responsibility or liability for any errors or inaccuracies that may appear in this document. The software described in this document is furnished under license and may only be used or copied in accordance with the terms of such license.

Adobe, After Effects, PhotoDeluxe, Adobe Premiere, Photoshop, Adobe Illustrator, Adobe Type Manager, ATM and PostScript are either trademarks or registered trademarks of Adobe Systems Incorporated in the United States and/or other countries. Apple, Macintosh, and Mac are trademarks of Apple Computer, Inc. registered in the United States and other countries. Microsoft and Windows are either registered trademarks or trademarks of Microsoft Corporation in the United States and/or other countries. All other products are the property of their respective owners.

 

Preface

Welcome to the Adobe Photoshop® File Format Specification!

This document is the detailed specification of the Adobe Photoshop file format and other pertinent file formats that Adobe Photoshop reads and writes.

Audience

This document is provided for 3rd parties to read and write the Photoshop native file format. This document does not explain how to interpret the data. This document describes the format of the data only.

What Is In This Document

This document has three chapters:

The Photoshop File Format describes the Photoshop PSD and PSB native file format in detail.

Other Document File Formats discusses Photoshop's handling of the EPS and TIFF file formats, which Photoshop can also create and read.

Additional File Formats describes the formats of other files used by Photoshop to store information about such items as colors, contours, curves, levels and so forth.

For more information about file formats, you may wish to consult the Encyclopedia of Graphics File Formats by James D. Murray & William vanRyper (1994, O'Reilly & Associates, Inc., Sebastopol, CA, ISBN 1-56592-058-9).

SDK User to User Forum

The Adobe forums web page, http://www.adobe.com/support/forums, is also availble for discussion of SDK issues. From the page above follow the Photoshop link and then the Adobe Photoshop Developers link.



Contents

Preface

Audience

What Is In This Document

SDK User to User Forum

The Photoshop File Format

Introduction

Large Document Format

Windows

Mac OS

Photoshop File Format

File Header Section

Color Mode Data Section

Image Resources Section

Image Resource Blocks

Image Resource IDs

Layer and Mask Information Section

Additional Layer Information

Image Data Section

Other Document File Formats

Photoshop EPS files

TIFF files

Photoshop-specific TIFF Tags

TIFF Files on Mac OS

Additional File Formats

Actions

Arbitrary Map

Single active channels

CMYK Setup

Color Books

Color Table

Color Swatches

Contours

Curves

Custom Kernel

Duotone Options

Halftone Screens

Hue/Saturation

Levels

Monitor Setup

Replace Color/Color Range

Selective Color

Separation Tables

Transfer Function

 

The Photoshop File Format

Introduction

This chapter discusses the Photoshop native file format

Photoshop file types

OS

Filetype/extension

Mac OS

8BPS

Windows

.PSD

Large Document Format

The Large Document Format (8BPB/PSB) supports documents up to 300,000 pixels in any dimension. All Photoshop features, such as layers, effects, and filters, are supported by the PSB format. The PSB format is identical to the Photoshop native format in many ways. This document will cover the differences found in the PSB format by donating a **PSB** marker.

Windows

All data is stored in big endian byte order. On the Windows platform, you must byte swap short and long integers when reading or writing.

Mac OS

For cross-platform compatibility, all information needed by Photoshop is stored in the data fork. For interoperability with other Macintosh applications, however, some information is duplicated in resources stored in the resource fork of the file:

For compatibility with image cataloging applications, the 'pnot' resource id 0 contains references to thumbnail, keywords, and caption information stored in other resources.

The thumbnail picture is stored in a 'PICT' resource, the keywords are stored in 'STR#' resource 128 and the caption text is stored in 'TEXT' resource 128. For more information on the format of these resources see Inside Macintosh: QuickTime Components and the Extensis Fetch Awareness Developer's Toolkit .

Photoshop also creates 'icl8' -16455 and 'ICN#' -16455 resources containing thumbnail images which will be shown in the Mac OS Finder.

All of the data from Photoshop's File Info dialog is stored in 'ANPA' resource 10000. The data in this resource is stored as an IPTC-NAA record 2.For more information on the format of this resource, see the documents in the IPTC folder of the Documentation folder.

Photoshop File Format

The Photoshop file format is divided into five major parts, as shown in the Photoshop file structure. The Photoshop file format has many length markers. Use these length markers to move from one section to the next. The length markers are usually padded with bytes to round to the nearest 2 or 4 byte interval.

Photoshop file structure
Photoshop File Format

File header (File Header Section).

Color mode data (Color Mode Data Section)

Image resources (Image Resources Section)

Layer and mask information (Layer and Mask Information Section)

Image data (Image Data Section).

The file header has a fixed length; the other four sections are variable in length.

When writing one of these sections, you should write all fields in the section, as Photoshop may try to read the entire section. Whenever writing a file and skipping bytes, you should explicitly write zeros for the skipped fields.

When reading one of the length-delimited sections, use the length field to decide when you should stop reading. In most cases, the length field indicates the number of bytes, not records, following.

The values in "Length" column in all tables are in bytes.

All values defined as Unicode string consist of:

A 4-byte length field, representing the number of characters in the string (not bytes).

The string of Unicode values, two bytes per character.

File Header Section

The file header contains the basic properties of the image.

File header section

Length

Description

4

Signature: always equal to '8BPS' . Do not try to read the file if the signature does not match this value.

2

Version: always equal to 1. Do not try to read the file if the version does not match this value. (**PSB** version is 2.)

6

Reserved: must be zero.

2

The number of channels in the image, including any alpha channels. Supported range is 1 to 56.

4

The height of the image in pixels. Supported range is 1 to 30,000.

(**PSB** max of 300,000.)

4

The width of the image in pixels. Supported range is 1 to 30,000.

(*PSB** max of 300,000)

2

Depth: the number of bits per channel. Supported values are 1, 8, 16 and 32.

2

The color mode of the file. Supported values are: Bitmap = 0; Grayscale = 1; Indexed = 2; RGB = 3; CMYK = 4; Multichannel = 7; Duotone = 8; Lab = 9.

Color Mode Data Section

The color mode data section is structured as follows:

Color mode data section

Length

Description

4

The length of the following color data.

Variable

The color data.

Only indexed color and duotone (see the mode field in the File header section) have color mode data. For all other modes, this section is just the 4-byte length field, which is set to zero.

Indexed color images: length is 768; color data contains the color table for the image, in non-interleaved order.

Duotone images: color data contains the duotone specification (the format of which is not documented). Other applications that read Photoshop files can treat a duotone image as a gray image, and just preserve the contents of the duotone information when reading and writing the file.

Image Resources Section

The third section of the file contains image resources. It starts with a length field, followed by a series of resource blocks.

Image resources section

Length

Description

4

Length of image resource section. The length may be zero.

Variable

Image resources (Image Resource Blocks ).

Image Resource Blocks

Image resource blocks are the basic building unit of several file formats, including Photoshop's native file format, JPEG, and TIFF. Image resources are used to store non-pixel data associated with images, such as pen tool paths.

They are referred to as resource blocks because they hold data that was stored in the Macintosh's resource fork in early versions of Photoshop.

The basic structure of image resource blocks is shown in the Image resource block. The last field is the data area, which varies by resource type. The makeup of each resource type is described in the following sections.

Image resource block

Length

Description

4

Signature: '8BIM'

2

Unique identifier for the resource. Image resource IDs contains a list of resource IDs used by Photoshop.

Variable

Name: Pascal string, padded to make the size even (a null name consists of two bytes of 0)

4

Actual size of resource data that follows

Variable

The resource data, described in the sections on the individual resource types. It is padded to make the size even.

Image Resource IDs

Image resources use several standard ID numbers, as shown in the Image resource IDs. Not all file formats use all ID's. Some information may be stored in other sections of the file.

For those resource IDs that have been added since Photoshop 3.0. the entry indicates the version in which they were introduced, e.g. ( Photoshop 6.0).

Image resource IDs

ID

Description

Hex

Decimal

0x03E8

1000

(Obsolete--Photoshop 2.0 only ) Contains five 2-byte values: number of channels, rows, columns, depth, and mode

0x03E9

1001

Macintosh print manager print info record

0x03EB

1003

(Obsolete--Photoshop 2.0 only ) Indexed color table

0x03ED

1005

ResolutionInfo structure. See Appendix A in Photoshop API Guide.pdf.

0x03EE

1006

Names of the alpha channels as a series of Pascal strings.

0x03EF

1007

(Obsolete) See ID 1077DisplayInfo structure. See Appendix A in Photoshop API Guide.pdf.

0x03F0

1008

The caption as a Pascal string.

0x03F1

1009

Border information. Contains a fixed number (2 bytes real, 2 bytes fraction) for the border width, and 2 bytes for border units (1 = inches, 2 = cm, 3 = points, 4 = picas, 5 = columns).

0x03F2

1010

Background color. See See Color structure.

0x03F3

1011

Print flags. A series of one-byte boolean values (see Page Setup dialog): labels, crop marks, color bars, registration marks, negative, flip, interpolate, caption, print flags.

0x03F4

1012

Grayscale and multichannel halftoning information

0x03F5

1013

Color halftoning information

0x03F6

1014

Duotone halftoning information

0x03F7

1015

Grayscale and multichannel transfer function

0x03F8

1016

Color transfer functions

0x03F9

1017

Duotone transfer functions

0x03FA

1018

Duotone image information

0x03FB

1019

Two bytes for the effective black and white values for the dot range

0x03FC

1020

(Obsolete)

0x03FD

1021

EPS options

0x03FE

1022

Quick Mask information. 2 bytes containing Quick Mask channel ID; 1- byte boolean indicating whether the mask was initially empty.

0x03FF

1023

(Obsolete)

0x0400

1024

Layer state information. 2 bytes containing the index of target layer (0 = bottom layer).

0x0401

1025

Working path (not saved). See See Path resource format.

0x0402

1026

Layers group information. 2 bytes per layer containing a group ID for the dragging groups. Layers in a group have the same group ID.

0x0403

1027

(Obsolete)

0x0404

1028

IPTC-NAA record. Contains the File Info... information. See the documentation in the IPTC folder of the Documentation folder.

0x0405

1029

Image mode for raw format files

0x0406

1030

JPEG quality. Private.

0x0408

1032

(Photoshop 4.0) Grid and guides information. See See Grid and guides resource format.

0x0409

1033

(Photoshop 4.0) Thumbnail resource for Photoshop 4.0 only. See See Thumbnail resource format.

0x040A

1034

(Photoshop 4.0) Copyright flag. Boolean indicating whether image is copyrighted. Can be set via Property suite or by user in File Info...

0x040B

1035

(Photoshop 4.0) URL. Handle of a text string with uniform resource locator. Can be set via Property suite or by user in File Info...

0x040C

1036

(Photoshop 5.0) Thumbnail resource (supersedes resource 1033). See See Thumbnail resource format.

0x040D

1037

(Photoshop 5.0) Global Angle. 4 bytes that contain an integer between 0 and 359, which is the global lighting angle for effects layer. If not present, assumed to be 30.

0x040E

1038

(Obsolete) See ID 1073 below. (Photoshop 5.0) Color samplers resource. See See Color samplers resource format.

0x040F

1039

(Photoshop 5.0) ICC Profile. The raw bytes of an ICC (International Color Consortium) format profile. See ICC1v42_2006-05.pdf in the Documentation folder and icProfileHeader.h in Sample Code\Common\Includes .

0x0410

1040

(Photoshop 5.0) Watermark. One byte.

0x0411

1041

(Photoshop 5.0) ICC Untagged Profile. 1 byte that disables any assumed profile handling when opening the file. 1 = intentionally untagged.

0x0412

1042

(Photoshop 5.0) Effects visible. 1-byte global flag to show/hide all the effects layer. Only present when they are hidden.

0x0413

1043

(Photoshop 5.0) Spot Halftone. 4 bytes for version, 4 bytes for length, and the variable length data.

0x0414

1044

(Photoshop 5.0) Document-specific IDs seed number. 4 bytes: Base value, starting at which layer IDs will be generated (or a greater value if existing IDs already exceed it). Its purpose is to avoid the case where we add layers, flatten, save, open, and then add more layers that end up with the same IDs as the first set.

0x0415

1045

(Photoshop 5.0) Unicode Alpha Names. Unicode string

0x0416

1046

(Photoshop 6.0) Indexed Color Table Count. 2 bytes for the number of colors in table that are actually defined

0x0417

1047

(Photoshop 6.0) Transparency Index. 2 bytes for the index of transparent color, if any.

0x0419

1049

(Photoshop 6.0) Global Altitude. 4 byte entry for altitude

0x041A

1050

(Photoshop 6.0) Slices. See See Slices resource format.

0x041B

1051

(Photoshop 6.0) Workflow URL. Unicode string

0x041C

1052

(Photoshop 6.0) Jump To XPEP. 2 bytes major version, 2 bytes minor version, 4 bytes count. Following is repeated for count: 4 bytes block size, 4 bytes key, if key = 'jtDd' , then next is a Boolean for the dirty flag; otherwise it's a 4 byte entry for the mod date.

0x041D

1053

(Photoshop 6.0) Alpha Identifiers. 4 bytes of length, followed by 4 bytes each for every alpha identifier.

0x041E

1054

(Photoshop 6.0) URL List. 4 byte count of URLs, followed by 4 byte long, 4 byte ID, and Unicode string for each count.

0x0421

1057

(Photoshop 6.0) Version Info. 4 bytes version, 1 byte hasRealMergedData , Unicode string: writer name, Unicode string: reader name, 4 bytes file version.

0x0422

1058

(Photoshop 7.0) EXIF data 1. See http://www.kodak.com/global/plugins/acrobat/en/service/digCam/exifStandard2.pdf

0x0423

1059

(Photoshop 7.0) EXIF data 3. See http://www.kodak.com/global/plugins/acrobat/en/service/digCam/exifStandard2.pdf

0x0424

1060

(Photoshop 7.0) XMP metadata. File info as XML description. See http://www.adobe.com/devnet/xmp/

0x0425

1061

(Photoshop 7.0) Caption digest. 16 bytes: RSA Data Security, MD5 message-digest algorithm

0x0426

1062

(Photoshop 7.0) Print scale. 2 bytes style (0 = centered, 1 = size to fit, 2 = user defined). 4 bytes x location (floating point). 4 bytes y location (floating point). 4 bytes scale (floating point)

0x0428

1064

(Photoshop CS) Pixel Aspect Ratio. 4 bytes (version = 1 or 2), 8 bytes double, x / y of a pixel. Version 2, attempting to correct values for NTSC and PAL, previously off by a factor of approx. 5%.

0x0429

1065

(Photoshop CS) Layer Comps. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure)

0x042A

1066

(Photoshop CS) Alternate Duotone Colors. 2 bytes (version = 1), 2 bytes count, following is repeated for each count: [ Color: 2 bytes for space followed by 4 * 2 byte color component ], following this is another 2 byte count, usually 256, followed by Lab colors one byte each for L, a, b. This resource is not read or used by Photoshop.

0x042B

1067

(Photoshop CS)Alternate Spot Colors. 2 bytes (version = 1), 2 bytes channel count, following is repeated for each count: 4 bytes channel ID, Color: 2 bytes for space followed by 4 * 2 byte color component. This resource is not read or used by Photoshop.

0x042D

1069

(Photoshop CS2) Layer Selection ID(s). 2 bytes count, following is repeated for each count: 4 bytes layer ID

0x042E

1070

(Photoshop CS2) HDR Toning information

0x042F

1071

(Photoshop CS2) Print info

0x0430

1072

(Photoshop CS2) Layer Group(s) Enabled ID. 1 byte for each layer in the document, repeated by length of the resource. NOTE: Layer groups have start and end markers

0x0431

1073

(Photoshop CS3) Color samplers resource. Also see ID 1038 for old format. See See Color samplers resource format.

0x0432

1074

(Photoshop CS3) Measurement Scale. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure)

0x0433

1075

(Photoshop CS3) Timeline Information. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure)

0x0434

1076

(Photoshop CS3) Sheet Disclosure. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure)

0x0435

1077

(Photoshop CS3) DisplayInfo structure to support floating point clors. Also see ID 1007. See Appendix A in Photoshop API Guide.pdf .

0x0436

1078

(Photoshop CS3) Onion Skins. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure)

0x0438

1080

(Photoshop CS4) Count Information. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure) Information about the count in the document. See the Count Tool.

0x043A

1082

(Photoshop CS5) Print Information. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure) Information about the current print settings in the document. The color management options.

0x043B

1083

(Photoshop CS5) Print Style. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure) Information about the current print style in the document. The printing marks, labels, ornaments, etc.

0x043C

1084

(Photoshop CS5) Macintosh NSPrintInfo. Variable OS specific info for Macintosh. NSPrintInfo. It is recommened that you do not interpret or use this data.

0x043D

1085

(Photoshop CS5) Windows DEVMODE. Variable OS specific info for Windows. DEVMODE. It is recommened that you do not interpret or use this data.

0x043E

1086

(Photoshop CS6) Auto Save File Path. Unicode string. It is recommened that you do not interpret or use this data.

0x043F

1087

(Photoshop CS6) Auto Save Format. Unicode string. It is recommened that you do not interpret or use this data.

0x0440

1088

(Photoshop CC) Path Selection State. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure) Information about the current path selection state.

0x07D0-0x0BB6

2000-2997

Path Information (saved paths). See See Path resource format.

0x0BB7

2999

Name of clipping path. See See Path resource format.

0x0BB8

3000

(Photoshop CC) Origin Path Info. 4 bytes (descriptor version = 16), Descriptor (see See Descriptor structure) Information about the origin path data.

0x0FA0-0x1387

4000-4999

Plug-In resource(s). Resources added by a plug-in. See the plug-in API found in the SDK documentation

0x1B58

7000

Image Ready variables. XML representation of variables definition

0x1B59

7001

Image Ready data sets

0x1F40

8000

(Photoshop CS3) Lightroom workflow, if present the document is in the middle of a Lightroom workflow.

0x2710

10000

Print flags information. 2 bytes version ( = 1), 1 byte center crop marks, 1 byte ( = 0), 4 bytes bleed width value, 2 bytes bleed width scale.

The following sections describe some of the resource formats in more detail.

Grid and guides resource format

Photoshop stores grid and guides information for an image in an image resource block. Each of these resource blocks consists of an initial 16-byte grid and guide header, which is always present, followed by 5-byte blocks of specific guide information for guide direction and location, which are present if there are guides ( fGuideCount > 0) .

Grid and guide header

Length

Description

4

Version ( = 1)

8

Future implementation of document-specific grids (4 bytes horizontal, 4 bytes vertical). Currently, sets the grid cycle to every quarter inch, i.e. 576 for both horizontal & vertical (at 72 dpi, that is 18 * 32 = 576)

4

fGuideCount : Number of guide resource blocks (can be 0).

 
Guide resource block

Length

Description

4

Location of guide in document coordinates. Since the guide is either vertical or horizontal, this only has to be one component of the coordinate.

1

Direction of guide. VHSelect is a system type of unsigned char where 0 = vertical, 1 = horizontal.

Grid and guide information may be modified using the Property suite. See the Callbacks chapter in Photoshop API Guide.pdf for more information.

Thumbnail resource format

Adobe Photoshop (version 5.0 and later) stores thumbnail information for preview display in an image resource block that consists of an initial 28-byte header, followed by a JFIF thumbnail in RGB (red, green, blue) order for both Macintosh and Windows.

Adobe Photoshop 4.0 stored the thumbnail information in the same format except the data section is BGR (blue, green, red). The 4.0 format is at resource ID 1033 and the 5.0 format is at resource ID 1036.

Thumbnail resource header

Length

Description

4

Format. 1 = kJpegRGB . Also supports kRawRGB (0).

4

Width of thumbnail in pixels.

4

Height of thumbnail in pixels.

4

Widthbytes: Padded row bytes = (width * bits per pixel + 31) / 32 * 4.

4

Total size = widthbytes * height * planes

4

Size after compression. Used for consistency check.

2

Bits per pixel. = 24

2

Number of planes. = 1

Variable

JFIF data in RGB format.

For resource ID 1033 the data is in BGR format.

Color samplers resource format

Adobe Photoshop (version 5.0 and later) stores color samplers information for an image in an image resource block that consists of an initial 8-byte color samplers header followed by a variable length block of specific color samplers information.

Color Samplers header

Length

Description

4

Version ( = 1, 2 or 3)

4

Number of color samplers to follow. See See Color Samplers resource block.

 
Color Samplers resource block

Length

Description

4

Version of color samplers, 1 for version 3. ( Version 3 only ) .

8

The horizontal and vertical position of the point (4 bytes each). Version 1 is a fixed value. Version 2 is a float value.

2

Color Space: enum { colorCodeDummy = -1, RGB, HSB, CMYK, Pantone, Focoltone, Trumatch, Toyo, Lab, Gray, WideCMYK, HKS, DIC, TotalInk, MonitorRGB, Duotone, Opacity, Web, GrayFloat, RGBFloat, OpacityFloat};

2

Depth ( Version 2 only )

Path resource format

Photoshop stores the paths saved with an image in an image resource block. These resource blocks consist of a series of 26-byte path point records, so the resource length should always be a multiple of 26.

Photoshop stores its paths as resources of type 8BIM , with IDs in the range 2000 through 2997. These numbers should be reserved for Photoshop. The name of the resource is the name given to the path when it was saved.

If the file contains a resource of type 8BIM with an ID of 2999, then this resource contains a Pascal-style string containing the name of the clipping path to use with this image when saving it as an EPS file. 4 byte fixed value for flatness and 2 byte fill rule. 0 = same fill rule, 1 = even odd fill rule, 2 = non zero winding fill rule. The fill rule is ignored by Photoshop.

The path format returned by GetProperty() call is identical to what is described below. Refer to the IllustratorExport sample plug-in code to see how this resource data is constructed.

Path points

All points used in defining a path are stored in eight bytes as a pair of 32-bit components, vertical component first.

The two components are signed, fixed point numbers with 8 bits before the binary point and 24 bits after the binary point. Three guard bits are reserved in the points to eliminate most concerns over arithmetic overflow. Hence, the range for each component is 0xF0000000 to 0x0FFFFFFF representing a range of -16 to 16. The lower bound is included, but not the upper bound.

This limited range is used because the points are expressed relative to the image size. The vertical component is given with respect to the image height, and the horizontal component is given with respect to the image width. [ 0,0 ] represents the top-left corner of the image; [ 1,1 ] ([ 0x01000000,0x01000000 ]) represents the bottom-right.

In Windows, the byte order of the path point components are reversed; you should swap the bytes when accessing each 32-bit value.

Path records

The data in a path resource consists of one or more 26-byte records. The first two bytes of each record is a selector to indicate what kind of path it is. For Windows, you should swap the bytes before accessing it as a short.

Path data record types

Selector

Description

0

Closed subpath length record

1

Closed subpath Bezier knot, linked

2

Closed subpath Bezier knot, unlinked

3

Open subpath length record

4

Open subpath Bezier knot, linked

5

Open subpath Bezier knot, unlinked

6

Path fill rule record

7

Clipboard record

8

Initial fill rule record

The first 26-byte path record contains a selector value of 6, path fill rule record. The remaining 24 bytes of the first record are zeroes. Paths use even/odd ruling. Subpath length records, selector value 0 or 3, contain the number of Bezier knot records in bytes 2 and 3. The remaining 22 bytes are unused, and should be zeroes. Each length record is then immediately followed by the Bezier knot records describing the knots of the subpath.

In Bezier knot records, the 24 bytes following the selector field contain three path points (described above) for:

the control point for the Bezier segment preceding the knot,

the anchor point for the knot, and

the control point for the Bezier segment leaving the knot.

Linked knots have their control points linked. Editing one point modifies the other to preserve collinearity. Knots should only be marked as having linked controls if their control points are collinear with their anchor. The control points on unlinked knots are independent of each other. Refer to the Adobe Photoshop User Guide for more information.

Clipboard records, selector=7 , contain four fixed-point numbers for the bounding rectangle (top, left, bottom, right), and a single fixed-point number indicating the resolution.

Initial fill records, selector=8 , contain one two byte record. A value of 1 means that the fill starts with all pixels. The value will be either 0 or 1.

Slices resource format

Adobe Photoshop 6.0 stores slices information for an image in an image resource block.

Adobe Photoshop 7.0 added a descriptor at the end of the block for the individual slice info.

Adobe Photoshop CS and later changed to version 7 or 8 and uses a Descriptor to defined the Slices data.

Slices header for version 7 or 8

Length

Description

4

Version ( = 7 and 8)

4

Descriptor version ( = 16 for Photoshop 6.0).

Variable

Descriptor (see See Descriptor structure)

Slices header for version 6

Length

Description

4

Version ( = 6)

4 * 4

Bounding rectangle for all of the slices: top, left, bottom, right of all the slices

Variable

Name of group of slices: Unicode string

4

Number of slices to follow. See Slices resource block in the next table.

 
Slices resource block

Length

Description

4

ID

4

Group ID

4

Origin

4

Associated Layer ID

Only present if Origin = 1

Variable

Name: Unicode string

4

Type

4 * 4

Left, top, right, bottom positions

Variable

URL: Unicode string

Variable

Target: Unicode string

Variable

Message: Unicode string

Variable

Alt Tag: Unicode string

1

Cell text is HTML: Boolean

Variable

Cell text: Unicode string

4

Horizontal alignment

4

Vertical alignment

1

Alpha color

1

Red

1

Green

1

Blue

Additional data as length allows. See comment above.

4

Descriptor version ( = 16 for Photoshop 6.0).

Variable

Descriptor (see See Descriptor structure)

 

Vanishing point resource format

Adobe Photoshop CS2 (9.0) and later stores vanishing point information for an image in an image resource block. The entire resource is a string with an id of 'tnaF' on Windows and 'FaNt' on the Macintosh. The structure of the resource is as follows:

Vocabulary:

Relation - a set of related planes.

Root Plane - the first plane in a relation.

Calibration Order - an ordering of the planes in a relation starting with the root plane, depth first, recursive traversal of the planes that are attached to the given plane.

Basics:

A planes area is represented as a clipped area of vanish rays. A Ray defines one of the virtual sides of the plane's area. A Ray's structure keeps track of information needed for tearing off and orientation issues. Parallel rays must point at the same VPID. A Primary ray's origin represents the point on the plane that is farthest from both VPs. The two primary rays share an origin.

version = 101

number of relations to follow.

-- for each relation--

grid resolution for the root plane

number of planes to follow

-- for each plane in calibration order--

ID of the plane

ID of the plane that calibrates this plane 0 if none

-- for 4 rays --

origin position of the ray. Point

VP location - must be consistent across all planes in the relation unless it is an endpoint. Point

true if the VP location is an endpoint

ID that this ray points at.

Ray DI (see below)

 

 

++++++++++++++++++++

I/O appendix

Point - two doubles; h endl, v endl

VPID - int (enum value) 0,1,2 identifing 1 of 3 possible VPs

RayID - 1, One of the primary rays directly connected to the shared origin

3, a non-primary ray parallel to 7

5, a non-primary ray parallel to 1

7, One of the primary rays directly connected to the shared origin .

Layer and Mask Information Section

The fourth section of a Photoshop file contains information about layers and masks. This section of the document describes the formats of layer and mask records.

The complete merged image data is not stored here. The complete merged/composite image resides in the last section of the file. See See Image Data Section. If maximize compatibility is unchecked then the merged/composite is not created and the layer data must be read to reproduce the final image.

See Layer and mask information section shows the overall structure of this section. If there are no layers or masks, this section is just 4 bytes: the length field, which is set to zero. (**PSB** length is 8 bytes

'Layr', 'Lr16' and 'Lr32' start at See Layer info. NOTE: The length of the section may already be known.)

When parsing this section pay close attention to the length of sections.

Layer and mask information section

Length

Description

4

Length of the layer and mask information section. (**PSB** length is 8 bytes.)

Variable

Layer info (see See Layer info for details).

Variable

Global layer mask info (see See Global layer mask info for details).

Variable

(Photoshop 4.0 and later)

Series of tagged blocks containing various types of data. See See Additional Layer Information for the list of the types of data that can be included here.

See Layer info shows the high-level organization of the layer information.

Layer info

Length

Description

4

Length of the layers info section, rounded up to a multiple of 2. (**PSB** length is 8 bytes.)

2

Layer count. If it is a negative number, its absolute value is the number of layers and the first alpha channel contains the transparency data for the merged result.

Variable

Information about each layer. See Layer records describes the structure of this information for each layer.

Variable

Channel image data. Contains one or more image data records (see See Channel image data for structure) for each layer. The layers are in the same order as in the layer information (previous row of this table).

 
Layer records

Length

Description

4 * 4

Rectangle containing the contents of the layer. Specified as top, left, bottom, right coordinates

2

Number of channels in the layer

6 *

number of channels

Channel information. Six bytes per channel, consisting of:

2 bytes for Channel ID: 0 = red, 1 = green, etc.;

-1 = transparency mask; -2 = user supplied layer mask, -3 real user supplied layer mask (when both a user mask and a vector mask are present)

4 bytes for length of corresponding channel data. (**PSB** 8 bytes for length of corresponding channel data.) See See Channel image data for structure of channel data.

4

Blend mode signature: '8BIM'

4

Blend mode key:

'pass' = pass through, 'norm' = normal, 'diss' = dissolve, 'dark' = darken, 'mul ' = multiply, 'idiv' = color burn, 'lbrn' = linear burn, 'dkCl' = darker color, 'lite' = lighten, 'scrn' = screen, 'div ' = color dodge, 'lddg' = linear dodge, 'lgCl' = lighter color, 'over' = overlay, 'sLit' = soft light, 'hLit' = hard light, 'vLit' = vivid light, 'lLit' = linear light, 'pLit' = pin light, 'hMix' = hard mix, 'diff' = difference, 'smud' = exclusion, 'fsub' = subtract, 'fdiv' = divide 'hue ' = hue, 'sat ' = saturation, 'colr' = color, 'lum ' = luminosity,

1

Opacity. 0 = transparent ... 255 = opaque

1

Clipping: 0 = base, 1 = non-base

1

Flags:
bit 0 = transparency protected;
bit 1 = visible;
bit 2 = obsolete;
bit 3 = 1 for Photoshop 5.0 and later, tells if bit 4 has useful information;
bit 4 = pixel data irrelevant to appearance of document

1

Filler (zero)

4

Length of the extra data field ( = the total length of the next five fields).

Variable

Layer mask data: See See Layer mask / adjustment layer data for structure. Can be 40 bytes, 24 bytes, or 4 bytes if no layer mask.

Variable

Layer blending ranges: See See Layer blending ranges data.

Variable

Layer name: Pascal string, padded to a multiple of 4 bytes.

Layer mask / adjustment layer data

Length

Name

4

Size of the data: Check the size and flags to determine what is or is not present. If zero, the following fields are not present

4 * 4

Rectangle enclosing layer mask: Top, left, bottom, right

1

Default color. 0 or 255

1

Flags.

bit 0 = position relative to layer
bit 1 = layer mask disabled
bit 2 = invert layer mask when blending (Obsolete)
bit 3 = indicates that the user mask actually came from rendering other data
bit 4 = indicates that the user and/or vector masks have parameters applied to them

1

Mask Parameters. Only present if bit 4 of Flags set above.

Variable

Mask Parameters bit flags present as follows:
bit 0 = user mask density, 1 byte
bit 1 = user mask feather, 8 byte, double
bit 2 = vector mask density, 1 byte
bit 3 = vector mask feather, 8 bytes, double

2

Padding. Only present if size = 20. Otherwise the following is present

1

Real Flags. Same as Flags information above.

1

Real user mask background. 0 or 255.

4 * 4

Rectangle enclosing layer mask: Top, left, bottom, right.

Layer blending ranges data

Length

Name

4

Length of layer blending ranges data

4

Composite gray blend source. Contains 2 black values followed by 2 white values. Present but irrelevant for Lab & Grayscale.

4

Composite gray blend destination range

4

First channel source range

4

First channel destination range

4

Second channel source range

4

Second channel destination range

...

...

4

Nth channel source range

4

Nth channel destination range

Channel image data

Length

Description

2

Compression. 0 = Raw Data, 1 = RLE compressed, 2 = ZIP without prediction, 3 = ZIP with prediction.

Variable

Image data.

If the compression code is 0, the image data is just the raw image data, whose size is calculated as (LayerBottom-LayerTop)* (LayerRight-LayerLeft) (from the first field in See Layer records).

If the compression code is 1, the image data starts with the byte counts for all the scan lines in the channel (LayerBottom-LayerTop) , with each count stored as a two-byte value.(**PSB** each count stored as a four-byte value.) The RLE compressed data follows, with each scan line compressed separately. The RLE compression is the same compression algorithm used by the Macintosh ROM routine PackBits, and the TIFF standard.

If the layer's size, and therefore the data, is odd, a pad byte will be inserted at the end of the row.

If the layer is an adjustment layer, the channel data is undefined (probably all white.)

Global layer mask info

Length

Description

4

Length of global layer mask info section.

2

Overlay color space (undocumented).

8

4 * 2 byte color components

2

Opacity. 0 = transparent, 100 = opaque.

1

Kind. 0 = Color selected--i.e. inverted; 1 = Color protected;128 = use value stored per layer. This value is preferred. The others are for backward compatibility with beta versions.

Variable

Filler: zeros

Additional Layer Information

There are several types of layer information that have been added in Photoshop 4.0 and later. These exist at the end of the layer records structure (see the last row of See Layer records). They have the following structure:

Additional layer information

Length

Description

4

Signature: '8BIM' or '8B64'

4

Key: a 4-character code (See individual sections)

4

Length data below, rounded up to an even byte count.

(**PSB**, the following keys have a length count of 8 bytes: LMsk, Lr16, Lr32, Layr, Mt16, Mt32, Mtrn, Alph, FMsk, lnk2, FEid, FXid, PxSD.

Variable

Data (See individual sections)

The following sections describe the different types of data available, their keys and their format.

Adjustment layer (Photoshop 4.0)

Adjustment layers can have one of the following keys:

'SoCo' = Solid Color

'GdFl' = Gradient

'PtFl' = Pattern

'brit' = Brightness/Contrast

'levl' = Levels

'curv' = Curves

'expA' = Exposure

'vibA' = Vibrance

'hue ' = Old Hue/saturation, Photoshop 4.0

'hue2' = New Hue/saturation, Photoshop 5.0

'blnc' = Color Balance

'blwh' = Black and White

'phfl' = Photo Filter

'mixr' = Channel Mixer

'clrL' = Color Lookup

'nvrt' = Invert

'post' = Posterize

'thrs' = Threshold

'grdm' = Gradient Map

'selc' = Selective color

 

The data for the adjustment layer is the same as the load file formats for each format. See See Additional File Formats for information.

Effects Layer (Photoshop 5.0)

The key for the effects layer is 'lrFX' . The data has the following format:

Effects Layer info

Length

Description

2

Version: 0

2

Effects count: may be 6 (for the 6 effects in Photoshop 5 and 6) or 7 (for Photoshop 7.0)

The next three items are repeated for each of the effects.

4

Signature: '8BIM'

4

Effects signatures: OSType key for which effects type to use:

'cmnS' = common state (see See Effects layer, common state info)

'dsdw' = drop shadow (see See Effects layer, drop shadow and inner shadow info)

'isdw' = inner shadow (see See Effects layer, drop shadow and inner shadow info)

'oglw' = outer glow (see See Effects layer, outer glow info)

'iglw' = inner glow (see See Effects layer, inner glow info)

'bevl' = bevel (see See Effects layer, bevel info)

'sofi' = solid fill ( Photoshop 7.0) (see See Effects layer, solid fill (added in Photoshop 7.0))

Variable

See appropriate tables.

 
Effects layer, common state info

Length

Description

4

Size of next three items: 7

4

Version: 0

1

Visible: always true

2

Unused: always 0

 
Effects layer, drop shadow and inner shadow info

Length

Description

4

Size of the remaining items: 41 or 51 (depending on version)

4

Version: 0 ( Photoshop 5.0) or 2 ( Photoshop 5.5)

4

Blur value in pixels

4

Intensity as a percent

4

Angle in degrees

4

Distance in pixels

10

Color: 2 bytes for space followed by 4 * 2 byte color component

8

Blend mode: 4 bytes for signature and 4 bytes for key

1

Effect enabled

1

Use this angle in all of the layer effects

1

Opacity as a percent

10

Native color: 2 bytes for space followed by 4 * 2 byte color component

 
Effects layer, outer glow info

Length

Description

4

Size of the remaining items: 32 for Photoshop 5.0; 42 for 5.5

4

Version: 0 for Photoshop 5.0; 2 for 5.5

4

Blur value in pixels.

4

Intensity as a percent

10

Color: 2 bytes for space followed by 4 * 2 byte color component

8

Blend mode: 4 bytes for signature and 4 bytes for the key

1

Effect enabled

1

Opacity as a percent

10

(Version 2 only) Native color space. 2 bytes for space followed by 4 * 2 byte color component

 
Effects layer, inner glow info

Length

Description

4

Size of the remaining items: 33 for Photoshop 5.0; 43 for 5.5

4

Version: 0 for Photoshop 5.0; 2 for 5.5.

4

Blur value in pixels.

4

Intensity as a percent

10

Color: 2 bytes for space followed by 4 * 2 byte color component

8

Blend mode: 4 bytes for signature and 4 bytes for the key

1

Effect enabled

1

Opacity as a percent

Remaining fields present only in version 2

1

Invert

10

(Version 2 only) Native color space. 2 bytes for space followed by 4 * 2 byte color component

 
Effects layer, bevel info

Length

Description

4

Size of the remaining items (58 for version 0, 78 for version 20

4

Version: 0 for Photoshop 5.0; 2 for 5.5

4

Angle in degrees

4

Strength. Depth in pixels

4

Blur value in pixels.

8

Highlight blend mode: 4 bytes for signature and 4 bytes for the key

8

Shadow blend mode: 4 bytes for signature and 4 bytes for the key

10

Highlight color: 2 bytes for space followed by 4 * 2 byte color component

10

Shadow color: 2 bytes for space followed by 4 * 2 byte color component

1

Bevel style

1

Hightlight opacity as a percent

1

Shadow opacity as a percent

1

Effect enabled

1

Use this angle in all of the layer effects

1

Up or down

The following are present in version 2 only

10

Real highlight color: 2 bytes for space; 4 * 2 byte color component

10

Real shadow color: 2 bytes for space; 4 * 2 byte color component

 
Effects layer, solid fill (added in Photoshop 7.0)

Length

Description

4

Size: 34

4

Version: 2

4

Key for blend mode

10

Color space

1

Opacity

1

Enabled

10

Native color space

Type Tool Info (Photoshop 5.0 and 5.5 only)

Has been superseded in Photoshop 6.0 and beyond by a different structure with the key 'TySh' (see See Type tool object setting (Photoshop 6.0) See Type tool object setting ).

Key is 'tySh' . Data is as follows:

Type tool Info

Length

Description

2

Version ( = 1)

48

6 * 8 double precision numbers for the transform information

Font information

2

Version ( = 6)

2

Count of faces

The next 8 fields are repeated for each count specified above

2

Mark value

4

Font type data

Variable

Pascal string of font name

Variable

Pascal string of font family name

Variable

Pascal string of font style name

2

Script value

4

Number of design axes vector to follow

4

Design vector value

Style information

2

Count of styles

The next 10 fields are repeated for each count specified above

2

Mark value

2

Face mark value

4

Size value

4

Tracking value

4

Kerning value

4

Leading value

4

Base shift value

1

Auto kern on/off

1

Only present in version <= 5

1

Rotate up/down

Text information

2

Type value

4

Scaling factor value

4

Sharacter count value

4

Horizontal placement

4

Vertical placement

4

Select start value

4

Select end value

2

Line count, i.e. the number of items to follow.

The next 5 fields are repeated for each item in line count.

4

Character count value

2

Orientation value

2

Alignment value

2

Actual character as a double byte character

2

Style value

Color information

2

Color space value

8

4 * 2 byte color component

1

Anti alias on/off

Unicode layer name (Photoshop 5.0)

Key is 'luni' . Data is as follows:

Unicode Layer name

Length

Description

Variable

Unicode string

Layer ID (Photoshop 5.0)

Key is 'lyid' .

Layer ID

Length

Description

4

Signature: '8BIM'

4

Key: 'lyid'

4

Length: 4

4

ID.

Object-based effects layer info (Photoshop 6.0)

Key is 'lfx2' . Data is as follows:

Object Based Effects Layer info

Length

Description

4

Object effects version: 0

4

Descriptor version ( = 16 for Photoshop 6.0).

Variable

Descriptor (see See Descriptor structure)

Patterns (Photoshop 6.0 and CS (8.0))

This is a list of patterns. Key is 'Patt', 'Pat2' or 'Pat3' . Data is as follows:

Patterns

Length

Description

The following is repeated for each pattern.

4

Length of this pattern

4

Version ( =1)

4

The image mode of the file. Supported values are: Bitmap = 0; Grayscale = 1; Indexed = 2; RGB = 3; CMYK = 4; Multichannel = 7; Duotone = 8; Lab = 9.

4

Point: vertical, 2 bytes and horizontal, 2 bytes

Variable

Name: Unicode string

Variable

Unique ID for this pattern: Pascal string

Variable

Index color table (256 * 3 RGB values): only present when image mode is indexed color

Variable

Pattern data as Virtual Memory Array List


Virtual Memory Array List

Length

Description

4

Version ( =3)

4

Length

16

Rectangle: top, left, bottom, right

4

Number of channels

The following is a virtual memory array, repeated for the number of channels + one for a user mask + one for a sheet mask.

4

Boolean indicating whether array is written, skip following data if 0.

4

Length, skip following data if 0.

4

Pixel depth: 1, 8, 16 or 32

16

Rectangle: top, left, bottom, right

2

Pixel depth: 1, 8, 16 or 32

1

Compression mode of data to follow. 1 is zip.

Variable

Actual data based on parameters and compression

Annotations (Photoshop 6.0)

Key is 'Anno' . Data is as follows:

Annotations

Length

Description

2

Major version ( = 2)

2

Minor version. ( = 1)

4

Count of annotations to follow

Following is repeated for each annotation

4

Length of this annotation

4

Annotation type: either text( 'txtA' ) or sound ( 'sndA' ).

1

Is the annotation open

1

Flags.

2

Optional blocks. ( =1 for Photoshop 6.0)

16

Rectangle of icon location: top, left, bottom and right.

16

Rectangle of popup locations: top, left, bottom and right

10

2 bytes for space followed by 4 * 2 byte color component

Variable

Pascal string of author's name aligned to 2 bytes

Variable

Pascal string of name aligned to 2 bytes

Variable

Pascal string of the mod Date aligned to 2 bytes

4

Length of the following 3 fields including this field

4

' txtC ' or ' sndM '. Either text or sound

4

Length of the next field

Variable

Actual data for this annotation. The text is an ASCII or Unicode string; the sound annotation is documented in the PDF Reference , available at http://Partners.adobe.com/asn/developer/acrosdk/docs.html#filefmtspecs

Variable

Padding to align to multiple of 4 bytes


Blend clipping elements (Photoshop 6.0)

Key is 'clbl' . Data is as follows:

Blend clipping elements

Length

Description

1

Blend clipped elements: boolean

3

Padding


Blend interior elements (Photoshop 6.0)

Key is'infx' . Data is as follows:

Blend interior elements

Length

Description

1

Blend interior elements: boolean

3

Padding

 

Knockout setting (Photoshop 6.0)

Key is 'knko' . Data is as follows:

Knockout setting

Length

Description

1

Knockout: boolean

3

Padding

 

Protected setting (Photoshop 6.0)

Key is 'lspf' . Data is as follows:

Protected setting

Length

Description

4

Protection flags: bits 0 - 2 are used for Photoshop 6.0. Transparency, composite and position respectively.

Sheet color setting (Photoshop 6.0)

Key is 'lclr' . Data is as follows:

Sheet Color setting

Length

Description

4 * 2

Color. Only the first color setting is used for Photoshop 6.0; the rest are zeros

 

Reference point (Photoshop 6.0)

Key is 'fxrp' . Data is as follows:

Reference point

Length

Description

2 * 8

2 double values for the reference point

 

Gradient settings (Photoshop 6.0)

Key is 'grdm' . Data is as follows:

Gradient settings

Length

Description

2

Version ( =1 for Photoshop 6.0)

1

Is gradient reversed

1

Is gradient dithered

Variable

Name of the gradient: Unicode string, padded

2

Number of color stops to follow

Following is repeated for each color stop

4

Location of color stop

4

Midpoint of color stop

2

Mode for the color to follow

4 * 2

Actual color for the stop

2

Number of transparency stops to follow

Following is repeated for each transparency stop

4

Location of transparency stop

4

Midpoint of transparency stop

2

Opacity of transparency stop

2

Expansion count ( = 2 for Photoshop 6.0)

2

Interpolation if length above is non-zero

2

Length (= 32 for Photoshop 6.0)

2

Mode for this gradient

4

Random number seed

2

Flag for showing transparency

2

Flag for using vector color

4

Roughness factor

2

Color model

4 * 2

Minimum color values

4 * 2

Maximum color values

2

Dummy: not used in Photoshop 6.0

 

Section divider setting (Photoshop 6.0)

Key is 'lsct' . Data is as follows:

Section Divider setting

Length

Description

4

Type. 4 possible values, 0 = any other type of layer, 1 = open "folder", 2 = closed "folder", 3 = bounding section divider, hidden in the UI

Following is only present if length >= 12

4

Signature: '8BIM'

4

Key. See blend mode keys in See Layer records.

Following is only present if length >= 16

4

Sub type. 0 = normal, 1 = scene group, affects the animation timeline.

 

Channel blending restrictions setting (Photoshop 6.0)

Key is 'brst' . Data is as follows:

Channel blending restrictions setting

Length

Description

Following is repeated length / 4 times.

4

Channel number that is restricted

 

Solid color sheet setting (Photoshop 6.0)

Key is 'SoCo' . Data is as follows:

Solid color sheet setting

Length

Description

4

Version ( = 16 for Photoshop 6.0)

Variable

Descriptor. Based on the Action file format structure (see See Descriptor structure)

 

Pattern fill setting (Photoshop 6.0)

Key is 'PtFl' . Data is as follows:

Pattern fill setting

Length

Description

4

Version ( =16 for Photoshop 6.0)

Variable

Descriptor. Based on the Action file format structure (see See Descriptor structure)

 

Gradient fill setting (Photoshop 6.0)

Key is 'GdFl' . Data is as follows:

Gradient Fill Setting

Length

Description

4 bytes

Version ( = 16 for Photoshop 6.0)

Variable

Descriptor. Based on the Action file format structure (see See Descriptor structure)

 

Vector mask setting (Photoshop 6.0)

Key is 'vmsk' or 'vsms'. If key is 'vsms' then we are writing for (Photoshop CS6) and the document will have a 'vscg' key. Data is as follows:

Vector mask setting

Length

Description

4

Version ( = 3 for Photoshop 6.0)

4

Flags. bit 1 = invert, bit 2 = not link, bit 3 = disable

The rest of the data is path components, loop until end of the length.

Variable

Paths. See See Path resource format

 

Type tool object setting (Photoshop 6.0)

This supersedes the type tool info in Photoshop 5.0 (see See Type tool Info).

Key is 'TySh' . Data is as follows:

Type tool object setting

Length

Description

2

Version ( =1 for Photoshop 6.0)

6 * 8

Transform: xx, xy, yx, yy, tx, and ty respectively.

2

Text version ( = 50 for Photoshop 6.0)

4

Descriptor version ( = 16 for Photoshop 6.0)

Variable

Text data (see See Descriptor structure)

2

Warp version ( = 1 for Photoshop 6.0)

4

Descriptor version ( = 16 for Photoshop 6.0)

Variable

Warp data (see See Descriptor structure)

4 * 8

left, top, right, bottom respectively.

 

Foreign effect ID (Photoshop 6.0)

Key is 'ffxi' . Data is as follows:

Foreign effect ID

Length

Description

4

ID of the Foreign effect.

 

Layer name source setting (Photoshop 6.0)

Key is 'lnsr' . Data is as follows:

Layer name source setting

Length

Description

4

ID for the layer name

 

Pattern data (Photoshop 6.0)

Key is 'shpa' . Data is as follows:

Pattern data

Length

Description

4

Version ( = 0 for Photoshop 6.0)

4

Count of sets to follow

The following is repeated for the count above.

4

Pattern signature

4

Pattern key

4

Count of patterns in this set

1

Copy on sheet duplication

3

Padding

The following is repeated for the count of patterns above.

4

Color handling. Prefer convert = 'conv' , avoid conversion = 'avod' , luminance only = 'lumi'

Variable

Pascal string name of the pattern

Variable

Unicode string name of the pattern

Variable

Pascal string of the unique identifier for the pattern

 

Metadata setting (Photoshop 6.0)

Key is 'shmd' . Data is as follows:

Metadata setting

Length

Description

4

Count of metadata items to follow

The following is repeated the number of times specified by the count above:

4

Signature of the data

4

Key of the data

1

Copy on sheet duplication

3

Padding

4

Length of data to follow

Variable

Undocumented data

 

Layer version (Photoshop 7.0)

Key is 'lyvr' . Data is as follows:

Layer version

Length

Description

4

A 32-bit number representing the version of Photoshop needed to read and interpret the layer without data loss. 70 = 7.0, 80 = 8.0, etc.

The minimum value is 70, because just having the field present in 6.0 triggers a warning. For the future, Photoshop 7 checks to see whether this number is larger than the current version -- i.e., 70 -- and if so, warns that it is ignoring some data.

 

Transparency shapes layer (Photoshop 7.0)

Key is 'tsly' . Data is as follows:

Transparency shapes layer

Length

Description

1

1: the transparency of the layer is used in determining the shape of the effects. This is the default for behavior like previous versions.

0: treated in the same way as fill opacity including modulating blend modes, rather than acting as strict transparency.

Using this feature is useful for achieving effects that otherwise would require complex use of clipping groups.

3

Padding

 

Layer mask as global mask (Photoshop 7.0)

Key is 'lmgm' . Data is as follows:

Layer mask as global mask

Length

Description

1

1: the layer mask is used in a final crossfade masking the layer and effects rather than being used to shape the layer and its effects.

This behavior was previously tied to the link status flag for the layer mask. (An unlinked mask acted like a flag value of 1, a linked mask like 0). For old files that lack this key, the link status is used in order to preserve compositing results.

3

Padding

 

Vector mask as global mask (Photoshop 7.0)

Key is 'vmgm' . Data is as follows:

Vector mask as global mask

Length

Description

1

Same as in See Layer mask as global mask, but applying the vector mask.

3

Padding

 

Brightness and Contrast

Key is 'brit' . Data is as follows:

Brightness and Contrast

Length

Description

2

Brightness

2

Contrast

2

Mean value for brightness and contrast

1

Lab color only

 

Channel Mixer

Key is 'mixr' . Data is as follows:

Channel Mixer

Length

Description

2

Version ( = 1)

2

Monochrome

20

RGB or CMYK color plus constant for the mixer settings. 4 * 2 bytes of color with 2 bytes of constant.

 

Color Lookup (Photoshop CS6)

Key is 'clrL' . Data is as follows:

Color Lookup

Length

Description

2

Version ( = 1)

4

Descriptor Version ( = 16)

Variable

Descriptor of black and white information

 

Placed Layer (replaced by SoLd in Photoshop CS3)

Key is 'plLd' . Data is as follows:

Placed Layer

Length

Description

4

Type ( = 'plcL' )

4

Version ( = 3 )

Variable

Unique ID as a pascal string

4

Page number

4

Total pages

4

Anit alias policy

4

Placed layer type: 0 = unknown, 1 = vector, 2 = raster, 3 = image stack

4 * 8

Transformation: 8 doubles for x,y location of transform points

4

Warp version ( = 0 )

4

Warp descriptor version ( = 16 )

Variable

Descriptor for warping information

 

Linked Layer

Key is 'lnkD' . Also keys 'lnk2' and 'lnk3' . Data is as follows:

Linked Layer

Length

Description

The following is repeated for each linked file.

8

Length of the data to follow

4

Type ( = 'liFD' )

4

Version ( = 2 )

Variable

Pascal string. Unique ID.

Variable

Unicode string of the original file name

4

File Type

4

File Creator

8

Length of the data to follow

1

File open descriptor

Variable

Descriptor of open parameters. Only present when above is true.

Variable

Raw bytes of the file.

 

Photo Filter

Key is 'phfl' . Data is as follows:

Photo Filter

Length

Description

2

Version ( = 3) or ( = 2 )

12

4 bytes each for XYZ color (Only in Version 3)

10

2 bytes color space followed by 4 * 2 bytes color component (Only in Version 2)

4

Density

1

Preserve Luminosity

 

Black White (Photoshop CS3)

Key is 'blwh' . Data is as follows:

Black White

Length

Description

4

Descriptor Version ( = 16)

Variable

Descriptor of black and white information

 

Content Generator Extra Data (Photoshop CS5)

Key is 'CgEd' . Data is as follows:

Content Generator Extra Data

Length

Description

4

Descriptor Version ( = 16)

Variable

Descriptor of extra data

 

Text Engine Data (Photoshop CS3)

Key is 'Txt2' . Data is as follows:

Text Engine Data

Length

Description

4

Length of data to follow

Variable

Raw bytes for text engine

 

Vibrance (Photoshop CS3)

Key is 'vibA' . Data is as follows:

Vibrance

Length

Description

4

Descriptor Version ( = 16)

Variable

Descriptor of vibrance information

 

Unicode Path Name (Photoshop CS6)

Key is 'pths' . Data is as follows:

Unicode Path Name

Length

Description

4

Descriptor Version ( = 16)

Variable

Descriptor containing a list of unicode path names

 

Animation Effects (Photoshop CS6)

Key is 'anFX' . Data is as follows:

Animation Effects

Length

Description

4

Descriptor Version ( = 16)

Variable

Descriptor containing animation effects

 

Filter Mask (Photoshop CS3)

Key is 'FMsk' . Data is as follows:

Filter Mask

Length

Description

10

Color space

2

Opacity

 

Placed Layer Data (Photoshop CS3)

Key is 'SoLd' . See also 'PlLd' key. Data is as follows:

Filter Mask

Length

Description

4

Identifier ( = 'soLD' )

4

Version ( = 4 )

4

Descriptor Version ( = 16)

Variable

Descriptor of placed layer information

 

Vector Stroke Data (Photoshop CS6)

Key is 'vstk' . Data is as follows:

Vector stroke setting

Length

Description

4

Version ( = 16 )

Variable

Descriptor. Based on the Action file format structure (see See Descriptor structure)

 

Vector Stroke Content Data (Photoshop CS6)

Key is 'vscg' . Data is as follows:

Vector stroke content setting

Length

Description

4

Key for data

4

Version ( = 16 )

Variable

Descriptor. Based on the Action file format structure (see See Descriptor structure)

 

Using Aligned Rendering (Photoshop CS6)

Key is 'sn2P' . Data is as follows:

Using Aligned Rendering

Length

Description

4

Non zero is true for using aligned rendering

 

Vector Origination Data (Photoshop CC)

Key is 'vogk' . Data is as follows:

Vector origination setting

Length

Description

4

Version ( = 1 for Photoshop CC)

4

Version ( = 16 )

Variable

Descriptor. Based on the Action file format structure (see See Descriptor structure)

 

Saving Merged Transparency

Key is 'Mtrn', 'Mt16' or 'Mt32' . There is no data associated with these keys.

 

User Mask

Key is 'LMsk' .

User Mask

Length

Description

10

Color space

2

Opacity

1

Flag ( = 128 )

 

Exposure

Key is 'expA' .

Exposure

Length

Description

2

Version (= 1)

4

Exposure

4

Offset

4

Gamma

 

Filter Effects

Key is 'FXid' or 'FEid' .

Filter Effects

Length

Description

4

Version ( =1, 2 or 3)

8

Length of data to follow

The following is repeated for the given length.

Variable

Pascal string as identifier

4

Version ( = 1 )

8

Length

16

Rectangle: top, left, bottom, right

4

Depth

4

Max channels

The following is repeated for number of channels + a user mask + a sheet mask.

4

Boolean indicating whether array is written

8

Length

2

Compression mode of data to follow.

Variable

Actual data based on compression

End of repeating for channels

1

Next two items present or not

2

Compression mode of data to follow

Variable

Actual data based on compression

Image Data Section

The last section of a Photoshop file contains the image pixel data. Image data is stored in planar order: first all the red data, then all the green data, etc. Each plane is stored in scan-line order, with no pad bytes,

Image data section

Length

Description

2

Compression method:

0 = Raw image data

1 = RLE compressed the image data starts with the byte counts for all the scan lines (rows * channels), with each count stored as a two-byte value. The RLE compressed data follows, with each scan line compressed separately. The RLE compression is the same compression algorithm used by the Macintosh ROM routine PackBits , and the TIFF standard.

2 = ZIP without prediction

3 = ZIP with prediction.

Variable

The image data. Planar order = RRR GGG BBB, etc.

 

Other Document File Formats

Photoshop EPS files

The following summarizes the additional information Photoshop writes when creating EPS files:

Photoshop writes a high-resolution bounding box comment to the EPS file immediately following the traditional EPS bounding box comment. The comment begins with " %%HiResBoundingBox " and is followed by four numbers identical to those given for the bounding box except that they can have fractional components (i.e., a decimal point and digits after it). The traditional bounding box is written as the rounded version of the high resolution bounding box for compatibility.

Photoshop writes its image resources out to a block of data stored as follows:

%BeginPhotoshop: <length> <hex data>

EPS parameters for BeginPhotoshop

Field

Definition

length

Length of the image resource data.

hex data

Image resource data in hexadecimal.

Photoshop includes a comment in the EPS files it writes so that it is able to read them back in again. Third party programs that write pixel-based EPS files may want to include this comment in their EPS files, so Photoshop can read their files.

The comment must follow immediately after the %% comment block at the start of the file. The comment is:

%ImageData: <columns> <rows> <depth> <mode> <pad channels> <block size> <binary/hex> "<data start>"

 

EPS parameters for ImageData

Field

Definition

columns

Width of the image in pixels.

rows

Height of the image in pixels.

depth

Number of bits per channel. Must be 1 or 8.

mode

Image mode. Bitmap/grayscale = 1; Lab = 2; RGB = 3; CMYK = 4.

pad channels

Number of other channels store in the file. Ignored when reading. Photoshop uses this to include a grayscale image that is printed on non-color PostScript printers.

block size

Number of bytes per row per channel. Will be either 1 or formula (below):

1 = Data is interleaved.

(columns*depth+7)/8 =Data is stored in line-interleaved format, or there is only one channel.

binary/ascii

1 = Data is in binary format.

2 = Data is in hex ascii format.

data start

Entire PostScript line immediately preceding the image data. This entire line should not occur elsewhere in the PostScript header code, butit may occur at part of a line.

TIFF files

See TIFF Tags describes the standard TIFF (version 6) tags and tag values that Photoshop is able to read and write. Photoshop reads the first Image File Directory (IFD) and writes one IFD per file.

In addition, Photoshop uses a set of tags that are not defined in the TIFF v6 specification to store specific information. See See Photoshop-specific TIFF Tags.

See See TIFF Files on Mac OS for information about how TIFF files are stored on Macintosh.

TIFF Tags

Tag

Name

Photoshop reads

Photoshop writes

254

NewSubFileType

Ignored

0

256

ImageWidth

1 to 30000

1 to 30000

257

ImageLength

1 to 30000

1 to 30000

258

BitsPerSample

1, 2, 4, 8, 16 (all same)

1, 8, 16

259

Compression

1 (uncompressed), 2 (CCITT), 5 (LZW), 7 (JPEG), 8 (ZIP), 32773 (PackBits)

1, 5, 7, 8

262

PhotometricInterpretation

0, 1, 2, 3, 5, 8, 9

0 (1-bit), 1 (8-bit), 2, 3,5,8

266

FillOrder

1

No

270

ImageDescription

Printing Caption

Printing Caption

271

EXIF: Make

 

 

272

EXIF: Model

 

 

273

StripOffsets

Yes

Yes

277

SamplesPerPixel

1 to 24

1 to 24

278

RowsPerStrip

Any

Single strip if not compressed, multiple strips if compressed.

279

StripByteCounts

Required if compressed

Yes

282

XResolution

Yes

Yes

283

YResolution

Ignored (square pixels assumed)

Yes

284

PlanarConfiguration

1 or 2

1

296

ResolutionUnit

2 or 3

2

305

EXIF: Software

 

 

306

EXIF: Date/time

 

 

315

EXIF: Artist

 

 

317

Predictor

1 or 2

1 or 2

320

ColorMap

Yes

Yes

322

TileWidth

Yes

No

323

TileLength

Yes

No

324

TileOffsets

Yes

No

325

TileByteCounts

Required if compressed

No

332

InkSet

1

No

336

DotRange

Yes, if CMYK

Yes

338

ExtraSamples

Ignored (except for count)

Photoshop 5.5 and earlier writes 0. Photoshop 6.0 and later writes 0 or 1 based on the spec.

See Photoshop TIFF.pdf for additional information about tags 259 and 262.

Photoshop-specific TIFF Tags
Photoshop-specific TIFF tags

Tag

Description

330

tSubIFD . Documented in the TIFF-PM6.pdf file as a PageMaker extension

437

JPEG tables. See Photoshop TIFF.pdf for more information.

700

XMP metadata. See http://www.adobe.com/devnet/xmp/

33723

File information (IPTC-NAA record 2: see the documents in the IPTC folder of the Documentation folder).

34377

Photoshop image resources (see See Image Resources Section)

34665

EXIF IFD pointer. See http://www.kodak.com/global/plugins/acrobat/en/service/digCam/exifStandard2.pdf

34675

ICC Profiles (see the ICC1v42_2006-05.pdf file from the International Color Consortium in the Documentation folder of the Photoshop SDK)

34853

EXIF GPS info. See http://www.kodak.com/global/plugins/acrobat/en/service/digCam/exifStandard2.pdf

37724

tImageSourceData . Begins with the null-terminated string " Adobe Photoshop Document Data Block ", (**PSB** " Adobe Photoshop Document Data V0002 "), followed by data of various types. See Photoshop TIFF.pdf for a list .

50255

tAnnotations . See See Annotations for details.

TIFF Files on Mac OS

For cross-platform compatibility, all information in a Macintosh TIFF file is stored in the data fork. For interoperability with other Mac OS applications, however, some information is duplicated in resources stored in the resource fork of the file.

For compatibility with image cataloging applications, the 'pnot' resource id 0 contains references to thumbnail, keywords, and caption information stored in other resources.

The thumbnail picture is stored in a 'PICT' resource, the keywords are stored in 'STR#' resource 128 and the caption text is stored in 'TEXT' resource 128. For more information on the format of these resources see Inside Macintosh: QuickTime Components and the Extensis Fetch Awareness Developer's Toolkit .

All of the data from Photoshop's File Info dialog is stored in 'ANPA' resource 10000.

'STR ' resource -16396 contains a string indicating the application that created the TIFF file.

Photoshop also creates 'icl8' -16455 and 'ICN#' -16455 resources containing thumbnail images which are shown in the Mac OS Finder.

 

Additional File Formats

In addition to documents that the user creates in Adobe Photoshop (discussed in See The Photoshop File Format), there are a number of additional files used by Photoshop to store information about such items as colors, contours, curves, levels and so forth. These are known as load files.

This chapter describes the format of each load file. Some of the files can saved by the user; others are load only, as indicated in the sections.

Each file has a unique file type and file extension associated with it. Photoshop for Macintosh recognizes either, but does not require the use of the extension. In the file dialogs, Photoshop for Windows looks for files with the given file extension automatically; this can be overridden.

Under Mac OS, all information is stored in the data forks of Photoshop's load files. The files are completely interchangable with Windows or any other platform.

Consistent byte ordering is required across platforms when reading and writing load files. Photoshop stores multi-byte values with the high-order bytes first, (big-endian), as on Mac OS., which is the opposite of Windows' standard byte order.. For more information, see "Macintosh and Windows development" in chapter 2 of Photoshop API Guide.pdf .

Actions

Actions are accessed by means of the Actions palette. The object effects use the actions mechanism to output information to the PSD file format.

Action file types

OS

Filetype/extension

Mac OS

8BAC

Windows

.ATN

Each action file comprises an action set . The format of the action file is described in the table below:

Action file format

Length

Description

4

Version ( = 16)

Variable

Unicode string: action set name

1

Boolean: true if set is expanded for the Actions palette

4

Number of actions in action set

The following is repeated for each action in the set

2

Index of action

1

Boolean: true if Shift key needed for keyboard shortcut

1

Boolean: true if Command key needed for keyboard shortcut

2

Color index information

Variable

Unicode string: action name

1

Boolean: true if action is expanded in the Actions palette

4

Number of items in action

The following is repeated for each item

1

Boolean: true if action is expanded in the Actions palette

1

Boolean: true if action is enabled

1

Boolean: true if dialogs should be displayed

1

Options for displaying dialogs

4

Identifier: 'TEXT' or 'long'

Variable

Event: if identifier is 'TEXT' ,4 bytes of length followed by the string;

if identifier is 'long' , 4 bytes of itemID

Variable

Dictionary name: 4 bytes of length followed by the string

4

-1 if a descriptor follows or 0 for none.

Variable

Descriptor: see Descriptor structure (See Descriptor structure) for details

Descriptor structure

Length

Description

Variable

Unicode string: name from classID

Variable

classID: 4 bytes (length), followed either by string or (if length is zero) 4-byte classID

4

Number of items in descriptor

The following is repeated for each item in descriptor

Variable

Key: 4 bytes ( length) followed either by string or (if length is zero) 4-byte key

4

Type: OSType key

'obj ' = Reference

'Objc' = Descriptor

'VlLs' = List

'doub' = Double

'UntF' = Unit float

'TEXT' = String

'enum'= Enumerated

'long' = Integer

'bool' = Boolean

'GlbO' = GlobalObject same as Descriptor

'type' or GlbC'= Class

'alis' = Alias

'tdta' = Raw Data

Variable

Item type: see the tables below for each possible type

Reference Structure

Length

Description

4

Number of items

The following is repeated for each item in reference

4

OSType key for type to use:

'prop' = Property

'Clss' = Class

'Enmr' = Enumerated Reference

'rele' = Offset

'Idnt' = Identifier

'indx' = Index

'name' =Name

Variable

Item type: see the tables below for each possible Reference type

Property Structure

Length

Description

Variable

Unicode string: name from classID

Variable

classID: 4 bytes (length), followed either by string or (if length is zero) 4-byte classID

Variable

KeyID: 4 bytes (length), followed either by string or (if length is zero) 4-byte keyID

'#Pnt' = points: tagged unit value

'#Mlm' = millimeters: tagged unit value

Unit float structure

Length

Description

4

Units the following value is in. One of the following:

'#Ang' = angle: base degrees

'#Rsl' = density: base per inch

'#Rlt' = distance: base 72ppi

'#Nne' = none: coerced.

'#Prc'= percent: unit value

'#Pxl' = pixels: tagged unit value

8

Actual value (double)

Double structure

Length

Description

8

Actual value (double)

Class structure

Length

Description

Variable

Unicode string: name from classID

Variable

ClassID: 4 bytes (length), followed either by string or (if length is zero) 4-byte classID

String structure

Length

Description

Variable

String value as Unicode string

Enumerated reference

Length

Description

Variable

Unicode string: name from ClassID.

Variable

ClassID: 4 bytes (length), followed either by string or (if length is zero) 4-byte classID

Variable

TypeID: 4 bytes (length), followed either by string or (if length is zero) 4-byte typeID

Variable

enum: 4 bytes (length), followed either by string or (if length is zero) 4-byte enum

Offset structure

Length

Description

Variable

Unicode string: name from ClassID

Variable

ClassID: 4 bytes (length), followed either by string or (if length is zero) 4-byte classID

4

Value of the offset

Boolean structure

Length

Description

1

Boolean value

Alias structure

Length

Description

4

Length of data to follow

Variable

FSSpec for Macintosh or a handle to a string to the full path on Windows

List structure

Length

Description

4

Number of items in the list

The following is repeated for each item in list

4

OSType key for type to use. See See Descriptor structure for types.

Variable

See the tables above for each possible type

 
Integer

Length

Description

4

Value

 
Enumerated descriptor

Length

Description

Variable

Type: 4 bytes (length), followed either by string or (if length is zero) 4-byte typeID

Variable

Enum: 4 bytes (length), followed either by string or (if length is zero) 4-byte enum

 
Raw Data

Length

Description

Variable

Value

Arbitrary Map

Arbitrary Map files are accessed by means of the Curves dialog ( load only ).

Arbitrary map file types

OS

Filetype/extension

Mac OS

8BLT

Windows

.AMP

There is no version number written in the file.

The files are an even multiple of 256 bytes long. Each 256 bytes is a lookup table, where:

The first byte of the table corresponds to byte zero of the image.

The last byte of the table corresponds to byte 255 of the image.

A NULL table that has no effect on an image is a linear table of bytes from 0 to 255.

If the file has one table, it is applied to the image's channels according to these priorities:

If the image has a master composite channel, the table is applied to it. If not, then:

If the image has a single active channel, the table is applied to it. If not, then:

If the image has no composite channel and more than one active channel, the table is not applied.

If the file has exactly three tables, it is applied to the image's channels according to these priorities:

The tables are assumed to represent RGB lookups. They are applied to the first three channels in the image, leaving the master composite untouched. Or:

If the image has a single active channel, the tables are converted to grayscale and the result is applied to the active channel. Or:

The first table is treated as a master. The remaining tables are applied to the image channels in turn (second table is applied to first channel, third table is applied to second channel, etc.).

Single active channels

Photoshop handles single active channels in a special fashion. When saving a map applied to a single channel, only one table is written to the file. Similarly, when reading a file for application to a single active channel, the master table is the one that will be used on that channel. This allows easy application of a single file to both composite and grayscale images.

CMYK Setup

CMYK settings files are accessed in Photoshop's Color Settings dialog (load only) .

CMYK file types

OS

Filetype/extension

Mac OS

8BIC

Windows

.API

CMYK setup file format

Length

Description

2

Version ( = 7)

27*2

Nine sets of three short integers specifying th\e xyY (CIE) values for the inks and their combinations. The inks are specified in the order cyan, magenta, yellow, magenta-yellow (red), cyan-yellow (green), cyan-magenta (blue), cyan-magenta-yellow, followed by the white and black points. Each set is written in the order xyY where:

x = 0...10000, representing 0.0...1.0000. y = 1...10000, representing 0.0001...1.0000. Y = 0...20000, representing 0.00...200.00.

2

Dot gain. Short integer from -10...40, representing -10%...40%.

1

Use curves. = 1 if curves table present.

1

Filler: zero

13*4*2

Only present if "use curves" = 1.

4 sets of 13 short integers specifyting the cyan, magenta, yellow, and black curve percentages from the Dot Gain Curves dialog. 0...1000, representing 0.0...100.0 %

Variable

Separation setup: see See Separation file format

 
Separation file format

Length

Description

2

Version ( = 300)

2

Separation type. 0 = UCR separations; 1 = GCR separations

2

Blank ink limit (0...100)

2

Total ink limit (200...400)

2

Undercolor addition for GCR separations (0...100)

Variable

Black generation (spline) curve detailed in See Black generation curve data structure. See also the Curves data format in See Curves file format.

Black generation curve data structure

Length

Description

2

Number of points in curve ( 2...19)

2* number of points

Each curve point is a pair of short integers where the first number is the output value (vertical coordinate on the Black Generation dialog graph) and the second is the input value. All coordinates have range 0 to 255. A NULL curve (no change to image data) is represented by the following five-number, ten-byte sequence in a file:

2 0 0 255 255.

The black generation curve and the UCA limit must both be present even if the separation type is set to UCR ( = 0).

Color Books

Color book files (Photoshop 7.0) are automatically loaded by Photoshop; they cannot be saved or loaded via a menu item. You can place custom color books into the Presets\Color Books folder. Use the Custom button on the Adobe color picker to access them.

Color book file types

OS

Filetype/extension

Mac OS

8BCB

Windows

.ACB

Color book file format

Length

Description

4

Signature: 8BCB

2

Version ( =1 )

2

Book ID. Existing IDs: 3000 (ANPA), 3001 (Focoltone), 3002 (PantoneCoated), 3003 (PantoneProcess), 3004 (PantoneProSlim), 3005 (PantoneUncoated), 3006 (Toyo), 3007 (Trumatch), 3008 (HKSE), 3009 (HKSK), 3010 (HKSN), 3011 (HKSZ), 3012 (DIC), 3020 (PantonePastelCoated), 3021 (PantonePastelUncoated), 3022 (PantoneMetallic)

Variable

Unicode string: title

Variable

Unicode string: prefix

Variable

Unicode string: postfix

Variable

Unicode string: description

2

Number of colors (<= 8000)

2

Colors per page (<= 9)

2

Key color page; must be less than or equal to colers per page

2

Color type. 0 = RGB; 2 = CMYK; 7 = Lab

The following are repeated for the number of colors

Variable

Unicode string: name

6

Unique key for the color

4

Color values: 4 bytes for CMYK; 3 bytes for RGB and Lab

Color Table

Color Table files are accessed using the Colors palette (load only) .

Color table file types

OS

Filetype/extension

Mac OS

8BCT

Windows

.ACT

There is no version number written in the file. The file is exactly 76

long, and contains 256 RGB colors:

The first color in the table is index zero.

There are three bytes per color in the order Red, Green, Blue.

If loaded into the Colors palette, the colors will be installed in the color swatch list as RGB colors.

Color Swatches

Color swatch files are loaded and saved in Photoshop's Color Swatches palette. These are typically stored in the Color Swatches sub-directory in the Presets directory.

Color swatches file types

OS

Filetype/extension

Mac OS

8BCO

Windows

.ACO

 
Color swatches file format

Length

Description

2

Version ( =1 )

2

Count of colors in the file.

count *10

Colors. Each color is 10 bytes, as described in See Color structure.

At the end of a version 1 file is the version 2 information.

2

Version ( = 2 )

2

Count of colors in the file. The next two fields are repeated for each count.

count *10

Colors. Each color is 10 bytes, as described in See Color structure.

Variable

Unicode string: color name.

Color structure

Length

Description

2

The color space the color belongs to (see See Color space IDs).

8

Four short unsigned integers with the actual color data. If the color does not require four values, the extra values are undefined and should be written as zeros. See See Color space IDs.

Color space IDs

Color ID

Description

0

RGB.

The first three values in the color data are red , green , and blue . They are full unsigned 16-bit values as in Apple's RGBColor data structure. Pure red = 65535, 0, 0.

1

HSB.

The first three values in the color data are hue , saturation , and brightness . They are full unsigned 16-bit values as in Apple's HSVColor data structure. Pure red = 0,65535, 65535.

2

CMYK.

The four values in the color data are cyan , magenta , yellow , and black . They are full unsigned 16-bit values.

0 = 100% ink. For example, pure cyan = 0,65535,65535,65535.

7

Lab.

The first three values in the color data are lightness , a chrominance , and b chrominance .

Lightness is a 16-bit value from 0...10000. Chrominance components are each 16-bit values from -12800...12700. Gray values are represented by chrominance components of 0. Pure white = 10000,0,0.

8

Grayscale.

The first value in the color data is the gray value, from 0...10000.

Photoshop allows the specification of custom colors, such as those colors that are defined in a set of custom inks provided by a printing ink manufacturer. These colors can be stored in the Colors palette and streamed to and from load files. The details of a custom color's color data fields are not public and should be treated as a black box.

See Custom color spaces gives the color space IDs currently defined by Photoshop for some custom color spaces.

Custom color spaces

Color ID

Name

3

Pantone matching system

4

Focoltone colour system

5

Trumatch color

6

Toyo 88 colorfinder 1050

10

HKS colors

Contours

Contour settings files (Photoshop 6.0) are loaded and saved in Photoshop's Layer Effects dialog.

Contour file types

OS

Filetype/extension

Mac OS

8BFS

Windows

.SHC

Contour file format

Length

Description

4

Type ( = '8BFS' )

2

Version ( = 1 )

4

Count of contours

The following is repeated for each contour

4

Version ( = 1 or 2)

Variable

Unicode string: contour name

Variable

version 1 or 2 data follows. See See Contours Version 1 for version 1 and See Contours Version 2 for version 2.

 
Contours Version 1

Length

Description

2

Count of points

4* count

For each point: 4 bytes of point data (2 bytes vertical, 2 bytes horizontal_

4

Minimum input range

4

Maximum input range

 
Contours Version 2

Length

Description

2

Count of points

4 * count

For each point: Point data (2 bytes vertical, 2 bytes horizontal)

1 * count

For each point: boolean indicating whether the point is continuous

4

Min input range

4

Max input range

Curves

Curves settings files are loaded in Photoshop's Curves dialog and Black Generation curve dialog (from within Separation Setup Preferences). Curves files can also be loaded into any of Photoshop's transfer function dialogs, such as the Duotone Curve dialog from within Duotone Options, and Print transfer dialog. Curves are saved as .ATF and .ACV files.

When loaded into a transfer function dialog, only the first curve in a Curves file is used.

Curves file types

OS

Filetype/extension

Mac OS

8BSC

Windows

.CRV

Curves file format

Length

Description

2

Version ( = 1 or = 4)

2

Version 1 = bit map of curves in file
Version 4 = count of curves in the file

The following is the data for each curve specified by count above

2

Count of points in the curve (short integer from 2...19)

point count * 4

Curve points. Each curve point is a pair of short integers where the first number is the output value (vertical coordinate on the Curves dialog graph) and the second is the input value. All coordinates have range 0 to 255. See also See Null curves below.

Null curves

A NULL curve (no change to image data) is represented by the following five-number, ten-byte sequence in a file:

2 0 0 255 255

Displaying ink percentages

Photoshop allows the option of displaying ink percentages instead of pixel values; this is a display option only and the internal data is unchanged, with 100% ink equal to image data of 0 and 0% ink equal to image data of 255.

Curves data order

The first curve is a master curve that applies to all the composite channels (RGB) when in composite image mode.

The remaining curves apply to the active channels in order: curve two applies to channel one, curve three applies to channel two, etc., up until curve 17, which applies to channel 16.

Indexed color

The exception to the normal order, and the reason there are up to 19 curves, is when the mode is Indexed color. In this case:

The first curve is a master curve.

The next three curves are created for the Red, Green, and Blue portions of the image's color table, and they are applied to the first channel.

The remaining curves apply to any remaining alpha channel that is active: for instance, if channel two is active, curve five applies to it; if channel three is active, curve six applies to it, etc., up until curve 19, which applies to channel 16.

Single active channels

Photoshop handles single active channels in a special fashion. When saving the curves applied to a single channel, the settings are stored into the master curve, at the beginning of the file. Similarly, when reading a curves file for application to a single active channel, the master curve is the one that will be used on that channel. This allows easy application of a single file to both RGB and grayscale images.

Additional information

At the end of the Version 1 file is the following information:

Extra level record info marker 'Crv '

Extra curves marker

Length

Description

4

= 'Crv ' for extra curve information

2

Version ( = 4)

2

Count of items to follow.

The following is the data for each curve specified by count above

2

Before each curve is a channel index.

2

Count of points in the curve (short integer from 2...19)

point count * 4

Curve points. Each curve point is a pair of short integers where the first number is the output value (vertical coordinate on the Curves dialog graph) and the second is the input value. All coordinates have range 0 to 255. See also See Null curves below.

Custom Kernel

Kernel settings files are loaded and saved in Photoshop's Custom Filter dialog. .

Custom kernel file types

OS

Filetype/extension

Mac OS

8BCK

Windows

.ACF


Custom filter structure

Length

Description

50

Weights.

The first 25 values are the custom weights from -999...999, applied to pixels offset from each pixel by [-2,-2] to [2,2]. The values progress through horizontal offsets first, as follows:

{[-2,-2],[-1,-2],[ 0,-2],[ 1,-2],[ 2,-2],

[-2,-1],[-1,-1],[ 0,-1],[ 1,-1],[ 2,-1],

[-2, 0],[-1, 0],[ 0, 0],[ 1, 0],[ 2, 0],

[-2, 1],[-1, 1],[ 0, 1],[ 1, 1],[ 2, 1],

[-2, 2],[-1, 2],[ 0, 2],[ 1, 2],[ 2, 2]}

27*2

Ink colors.

Nine sets of three short integers specifying the xyY (CIE) values for the inks and their combinations. The inks are specified in the order cyan, magenta, yellow, magenta-yellow (red), cyan-yellow (green), cyan-magenta (blue), cyan-magenta-yellow, followed by the white and black points. Each set is written in the order xyY where:

x = 0...10000, representing 0.0...1.0000. y = 1...10000, representing 0.0001...1.0000. Y = 0...20000, representing 0.00...200.00.

2

Scale. Short integer from 1...9999.

2

Offset. Short integer from -9999...9999.


Duotone Options

Duotone settings files are loaded and saved in the Duotone Options dialog..

Duotone file types

OS

Filetype/extension

Mac OS

8BDT

Windows

.ADO


Duotone file format

Length

Description

2

Version ( = 1)

2

Count . Number of plates in duotone spec (short integer). 1 = Monotone; 2 = Duotone; 3 = Tritone; 4 = Quadtone.

4*10

Four ink colors, regardless of the number of plates. The contents of the colors beyond the last plate specified by Count are undefined. Each color is 10 bytes and described in See Duotone color structure. It is identical to the format in a Colors load file.

4*64

Four ink names, regardless of the number of plates. Each name is streamed as a Pascal-style string with a length byte followed by the string name. Names may not be more than 63 characters. Each name is padded to occupy 64 bytes, including the length byte. Any names beyond the last plate specified by Count should be empty, size = 0.

4*28

Four ink curves, regardless of the number of plates. Described in See Ink curves structure.

2

Dot gain ( = 20). Kept for compatability with Photoshop 2.0. Ignored.

11*10

Eleven overprint colorscolors, regardless of the number of plates. The number of defined overprints depends on Count .

Monotones = no overprint colors. Duotones = one overprint color. Tritones = four overprint colors. Quadtones = 11 overprint colors. The contents of the colors beyond the last defined overprint are undefined. Each color is 10 bytes and described in See Duotone color structure. It is identical to the format in a Colors load file.


Duotone color structure

Length

Description

2

The color space the color belongs to (see See Color space IDs).

8

Four short unsigned integers with the actual color data. If the color does not require four values to specify, the extra values are undefined and should be written as zeros.


Ink curves structure

Length

Description

26

Transfer curve: Array of 13 short integers from 0...1000 representing 0.0...100.0. All but the first and last value may be -1, representing no point on the curve. Any curves beyond the last plate should be equal to the NULL curve. A NULL transfer curve looks like this: 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1000.

2

Override ( = 0). Short integer for compatibility. Ignored by Photoshop 3.0 and higher.

Halftone Screens

Halftone Screens settings files are loaded and saved in Photoshop's Halftone Screens dialog (available from Edit > Print with Preview in Photoshop 7, or Page Setup or Print Options in previous versions).

Halftone screen file types

OS

Filetype/extension

Mac OS

8BHS

Windows

.AHS


Halftone screens file format

Length

Description

2

Version ( = 5)

4*18

Four screen descriptions. See See Halftone screen parameter structure.

Variable

For every screen that has a custom spot function, the PostScript function text is written here, one after the other, with no header information, in the same order as the screen settings. The size of each custom spot is the absolute value of its negative shape code.


Halftone screen parameter structure

Length

Description

4

Ink's screen frequency, in lines per inch. Binary fixed point value ;16 bits representing the integer and fractional parts from 1.0...999.999.

2

Units for the screen frequency. Lines per inch = 1; lines per centimeter = 2. Only affects display, not screen frequency.

4

Angle for screen. Binary fixed point value with 16 bits representing the integer and fractional parts from -180.0000 ... 180.0000, measured in degrees.

2

Code representing the shape of the halftone dots. 0 = Round; 1 = Ellipse; 2 = Line; 3 = Square; 4 = Cross; 6 = Diamond. Negative numbers represent custom shapes; the absolute value is the size in bytes of the custom spot function described in See Halftone screens file format.

4

= 0. Not currently used by Photoshop.

1

Boolean. 1 = Use accurate screens; 0 = Use other.

1

Boolean. 1 = Use printer's default screens; 0 = Use other.

Hue/Saturation

Hue/Saturation settings files are loaded and saved in Photoshop's Hue/Saturation dialog /

Hue/saturation file types

OS

Filetype/extension

Mac OS

8BHA

Windows

.AHV


Hue/saturation file format

Length

Description

2

Version ( = 2)

1

0 = Use settings for hue-adjustment; 1 = Use settings for colorization.

1

Padding byte; must be present but is ignored by Photoshop.

6

Colorization.

Photoshop 5.0: The actual values are stored for the new version. Hue is -180...180, Saturation is 0...100, and Lightness is -100...100.

Photoshop 4.0: Three short integers Hue, Saturation, and Lightness from -100...100. The user interface represents hue as -180...180, saturation as 0...100, and Lightness as -100...1000, as the traditional HSB color wheel, with red = 0.

6

Master hue, saturation and lightness values.

6 sets of the following 14 bytes (4 range values followed by 3 settings values)

8: range values

For RGB and CMYK, those values apply to each of the six hextants in the HSB color wheel: those image pixels nearest to red, yellow, green, cyan, blue, or magenta. These numbers appear in the user interface from -60...60, however the slider will reflect each of the possible 201 values from -100...100.

For Lab, the first four of the six values are applied to image pixels in the four Lab color quadrants, yellow, green, blue, and magenta. The other two values are ignored ( = 0). The values appear in the user interface from -90 to 90.

6:settings values

Levels

Levels settings files are loaded and saved in the Levels dialog.

Levels file types

OS

Filetype/extension

Mac OS

8BLS

Windows

.ALV


Levels file format

Length

Description

2

Version ( = 2)

29 * 10

29 sets of level records, each level containing 5 short integers (see See Level record structure).


Level record structure

Length

Description

2

Input floor (0...253)

2

Input ceiling (2...255)

2

Output floor (0...255). Matched to input floor.

2

Output ceiling (0...255)

2

Gamma. Short integer from 10...999 representing 0.1...9.99. Applied to all image data.

Level record sets order

The first set of levels is the master set that applies to all of the composite channels (RGB) when in composite image mode.

The remaining sets apply to the active channels individually; set two applies to channel one, the set three to channel two, etc., up until set 25, which applies to channel 24.

Sets 28 and 29 are reserved and should be set to zeros.

Indexed color

The exception to the normal order is when the mode is Indexed:

The first set is a master set.

The next three sets are created for the Red, Green, and Blue portions of the image's color table, and they are applied to the first channel.

The remaining sets apply to any remaining alpha channels that are active: for instance, if channel two is active, set five applies to it; if channel three is active, set six applies to it, etc., up until channel 27, which applies to channel 24.

Sets 28 and 29 are reserved and should be set to zeros.

Single active channels

Photoshop handles single active channels in a special fashion. When saving the levels applied to a single channel, the settings are stored into the master set, at the beginning of the file. Similarly, when reading a levels file for application to a single active channel, the master levels are the ones that will be used on that channel. This allows easy application of a single file to both RGB and grayscale images.

Photoshop CS (8.0) Additional information

At the end of the Version 2 file is the following information:

Extra level record info marker 'Lvls'

Extra levels marker

Length

Description

4

= 'Lvls' for extra level information

2

Version ( = 3)

2

Count of total level record structures. Subtract the legacy number of level record structures, 29, to determine how many are remaining in the file for reading.

Variable

Additianol level records according to count. See Level record structure

Monitor Setup

This format has been superseded by ICC profiles. See ICC1v42_2006-05.pdf for details.

Monitor settings files are accessed in Photoshop's Color Settings dialog, via the Edit menu (load only) .

Monitor setup file types

OS

Filetype/extension

Mac OS

8BMS

Windows

.AMS


Monitor setup file format

Length

Description

2

Version ( = 2.)

2

Gamma. Short integer from 75...300 representing 0.75...3.00.

2*2

White point. Two short integers as CIE chromaticity coordinates: x,y . x = 0...10000 representing 0.0...1.0000. y = 1...10000 representing 0.0001...1.0000.

6*2

Phosphors. Three sets of two integers giving x,y coordinates of the red, green, and blue phosphors. x = 0...10000 representing 0.0...1.0000. y = 1...10000 representing 0.0001...1.0000. In the order red x , red y ; green x , green y ; blue x , blue y .

Replace Color/Color Range

Replace Color settings files are loaded and saved in the Color Range dialog (available via the Select menu).

Replace color/Color range file types

OS

Filetype/extension

Mac OS

8BXT

Windows

.AXT


Replace color/Color range file format

Length

Description

2

Version ( = 1)

2

Short integer indicating what space the color components are in. 7 = Lab color, 8 = grayscale. No other values are supported.

6

Component ranges. Six unsigned byte values representing the range of colors within which a pixel's color must fall to be considered selected for color replacement, or color range selecting. Described in See Component range structure.

2

Fuzziness. Short integer from 0...200 controlling how colors close to selected colors are affected.

6

Transform settings.

When used with Replace Color: Three short integers from -100...100. Described in See Replace color transform settings.

When used with Color Range: Writes zeros into the three short integers and ignores.


 
Component range structure

Length

Description

1

if Lab (color space = 7): low endpoint of L value

if grayscale (color space = 8): low endpoint of gray range

1

if Lab: high endpoint of L value

if grayscale: 0

1

if Lab: low endpoint of a chrominance value

if grayscale: 0

1

if Lab: high endpoint of a chrominance value

if grayscale: 0

1

if Lab: low endpoint of b chrominance value

if grayscale: low endpoint of gray range

1

if Lab: high endpoint of b chrominance value

if grayscale: high endpoint of gray range


Replace color transform settings

Length

Description

2

Hue change. Short integer from -100...100.

2

Saturation change. Short integer from -100...100.

2

Lightness change Short integer from -100...100. .

Selective Color

Selective Color settings files are loaded and saved in Photoshop's Selective Color dialog.

Selective color file types

OS

Filetype/extension

Mac OS

8BSV

Windows

.ASV


Selective color file format

Length

Description

2

Version ( = 1)

2

Correction method.. 0 = Apply color correction in relative mode; 1 = Apply color correction in absolute mode.

80

Ten eight-byte plate correction records, described in See Plate correction structure.

The first record is ignored by Photoshop and is reserved for future use. It should be set to all zeroes.

The rest of the records apply to specific areas of colors or lightness values in the image, in the following order: reds, yellows, greens, cyans, blues, magentas, whites, neutrals, blacks.


Plate correction structure

Length

Description

2

Amount of cyan correction. Short integer from -100...100.

2

Amount of magenta correction. Short integer from -100...100.

2

Amount of yellow correction. Short integer from -100...100.

2

Amount of black correction. Short integer from -100...100.

Separation Tables

This format has been superseded by ICC profiles. See ICC1v42_2006-05.pdf for details.

Separation Table files are accessed in the Separation Tables dialog (load only) .

Separation table file types

OS

Filetype/extension

Mac OS

8BST

Windows

.AST

Format:

If the size of the file is 33 * 33 * 33 * 4 , then the file consists only of a
Lab->CMYK table as currently documented.

If the size of the file is ( 33 * 33 * 33 + 256 ) * 3 , then the file consists only of a CMYK->Lab table as currently documented.

Otherwise, the file has the format listed in See Separation table file format.


Separation table file format

Length

Description

2

Version ( = 300)

1

Boolean. True if contains Lab->CMYK table.

1

Boolean. True if contains CMYK->Lab table.

33*33*33*4

If file contains Lab->CMYK table, this section contains CMYK colors for 33*33*33 Lab colors. The CMYK colors are written in interleaved order, one byte each ink. 0 = 100%, 255 = 0%. See See Generating Lab source colors below.

(33*33*33 +256)*3

If file contains CMYK->Lab table, this section contains Lab colors for 33*33*33+256 CMYK colors. The Lab colors are written in interleaved order, one byte per component. See See Generating CMYK source colors below.

1

Boolean. True if gamut table follows.

1

If entry above is false , this byte will not be present.

If true, this byte should be set to 1 for compatibility.

(((33*33*33L)+7)>>3) if gamut table present, zero otherwise

Gamut table, if present. The gamut table is a bit table indexed in the same way as the Lab->CMYK table with the high bit of the first byte at index 0. See See Testing for bits in the gamut table below.

Generating Lab source colors

The Lab colors that are the source colors can be generated from the Lab->CMYK table with the following routine:

for (i = 0; i < 33; i++)

 for (j = 0; j < 33; j++)

  for (n = 0; n < 33; n++)

  {

   L = Min (i * 8, 255);

   a = Min (j * 8, 255);

   b = Min (n * 8, 255);

  }

Generating CMYK source colors

The CMYK colors that are the source colors can be generated from the CMYK->Lab table with the following routine:

for (i = 0; i < 33; i++)

 for (j = 0; j < 33; j++)

  for (n = 0; n < 33; n++)

  {

   c = Min (i * 8, 255);

   m = Min (j * 8, 255);

   y = Min (n * 8, 255);

   k = 255;

  }

for (i = 0; i < 256; i++)

{

 c = 255;

 m = 255;

 y = 255;

 k = i;

}

Testing for bits in the gamut table

To test the bit at bitIndex , use table:

([bitIndex >> 3] & (0x0080 >> (bitIndex & 0x07))) != 0.

bitIndex itself is calculated in the same way you would calculate an index into the Lab->CMYK table.

A result of 1 indicates that the color is in gamut and 0 indicates that it is out of gamut.

Transfer Function

Transfer Function settings files are accessed (load only) in Photoshop's Duotone Curve dialog from within Duotone Options and Transfer Function dialogs (available from Edit > Print with Preview in Photoshop 7, or Page Setup or Print Options in previous versions).Transfer Function files can also be loaded into any of Photoshop's curves dialogs, such as the Curves color adjustment dialog.

Transfer function file types

OS

Filetype/extension

Mac OS

8BTF

Windows

.ATF


Transfer function file format

Length

Description

2

Version ( = 4)

112 (= 28*4)

Four transfer functions , described in See Transfer function structure.

The file always contains four functions. When writing the printer transfer functions for grayscale images, for instance, Photoshop writes four copies of the single transfer function specified in the user interface.


Transfer function structure

Length

Description

26

Curve. Array of 13 short integers from 0...1000 representing 0.0...100.0. All but the first and last value may be -1, representing no point on the curve. Any curves beyond the last plate should be equal to the NULL curve. A NULL transfer curve looks like this: 0, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, -1, 1000.

2

Boolean. 0 = Let printer supply curve; 1 = Override printer's default transfer curve.