# PhotoshopElements

# Resample an image

Changing the pixel dimensions of an image is called resampling. Resampling affects not only the size of an image on‑screen, but also its image quality and its printed output—either its printed dimensions or its image resolution. Resampling can degrade image quality. When you downsample, meaning that you decrease the number of pixels in your image, information is removed from the image. When you upsample, or increase the number of pixels in your image, new pixels are added based on the color values of existing pixels, and the image loses some detail and sharpness.
Resampling an image

A.
  Image downsampled

B.
  Original image

C.
  Image upsampled

To avoid the need for upsampling, scan or create the image at the resolution required for your printer or output device. If you want to preview the effects of changing pixel dimensions on‑screen or print proofs at different resolutions, resample a duplicate of your file.

If you’re preparing images for the web, it’s useful to specify image size in terms of the pixel dimensions.

1. Choose Image > Resize > Image Size.
2. Select Resample Image, and choose an interpolation method:
   Nearest Neighbor
     Fast, but less precise. This method is recommended for use with illustrations containing edges that are not anti-aliased, to preserve hard edges and produce a smaller file. However, this method can create jagged edges, which become apparent when distorting or scaling an image or performing multiple manipulations on a selection.

   Bilinear
     Medium-quality.

   Bicubic
     Slow, but more precise, resulting in the smoothest tonal gradations.

   Bicubic Smoother
     Use when you're enlarging images.

   Bicubic Sharper
     Use when you’re reducing the size of an image. This method maintains the detail in a resampled image. It may, however, oversharpen some areas of an image. In this case, try using Bicubic.

3. To maintain the current aspect ratio, select Constrain Proportions. This option automatically updates the width as you change the height, and vice versa.
4. In Pixel Dimensions, enter values for Width and Height. To enter values as percentages of the current dimensions, choose Percent as the unit of measurement.

   The new file size of the image appears next to Pixel Dimensions, with the old file size in parentheses.

5. Click OK to change the pixel dimensions and resample the image.
   For best results in producing a smaller image, downsample and apply the Unsharp Mask filter. To produce a larger image, rescan the image at a higher resolution.

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