Seen on web browsers and smartphones everywhere, the JPEG file format is the bread and butter of everyday image file storage and display. Find out more about the history of JPEG images, what to use them for, and how to take advantage of their compression capabilities.
JPEG stands for Joint Photographic Experts Group, an international organisation that standardised the format during the late 1980s and early 1990s. It’s the go-to file format for digital images — and it has been ever since photographers began snapping and storing images on digital cameras and other reprographic devices.
JPEG images group together the following filename extensions:
A JPEG file supports up to 24-bit colour and uses lossy compression to compress images for more convenient storage and sending. This may make JPEGs better for everyday use, but it does mean sacrificing some of the original image quality.
In 1986, monitor technology couldn’t produce on-screen graphics. That’s when a group called the International Organisation for Standardisation (ISO) started working on ways to bring photo-realistic pictures to small screens around the world.
At the same time, the Joint Photographic Experts Group (JPEG) arrived on the scene and created its own standard to compress graphics files enough to work on the average PC. They came up with the concept of lossy compression, which removed visual data that the human eye couldn't see and averaged out colour variation.
JPEG files came into their own with the advent of digital cameras and the World Wide Web. Now, anyone could snap and store images in small enough files to fit on limited camera storage while displaying reasonably well. The real value came in the JPEG’s ability to store metadata — such as where and when a picture is taken and even camera settings.
Serious photographers still shy away from shooting in JPEGs because they want to keep all the image detail for post-processing or printing. But this file format is still very much a mainstream favourite.
A JPEG file can display 16.8 million colours while staying relatively small in size. That’s what makes it the go-to file for photographers and web publishers alike.
While photographers tend to shoot in a raw format to ensure the most accurate capture of a picture possible, they often share the fruits of their labour online in JPEG form. The smaller size means it’ll open faster on most browsers (including mobile) without sacrificing too much quality.
Everyone from big-time publishers to bloggers benefit from using JPEG files on their website. Faster page loading times gives readers quicker access to content — plus, JPEGs don’t take up too much storage space in the cloud.
The trade-off between file size and image quality is where the JPEG debate heats up.
If you’ve found an image on a web page and want to view it on its own, you can usually open it in a new tab. Right-click on the image (on PC) and select Open Image in New Tab or similar.
If you’re operating Safari or a different browser on a Mac, you’ll see the same type of option as above for opening an image in a new tab. Just hold down the Command key and click the image to bring up a menu, then select Open Image in New Tab.
Your computer should have a default image viewing programme such as Photos for Windows or Preview on Mac. To open a file that’s saved on your computer, double-click the image file on your desktop and it will open using the default programme.
Alternatively, you can use your preferred piece of software for viewing photos on Windows:
When you want to save a finished file in Adobe Photoshop, you can create a JPEG file by clicking the File menu, then selecting Save As.
You can return at any time to edit the file by opening Photoshop and using the File menu, then Open, to locate the file in your file explorer window. However, JPEG may not be the best choice for saving works-in-progress on Photoshop — the lossy compression can affect the image quality and you may lose some of the effect of the work. If this is the case for you, try saving as an alternative file format like PSD.
JPGs and JPEGs are the same. The three-letter file extension was due to the limitations of older versions of Windows and MS-DOS. All file extensions were limited to three characters — today, this is no longer the case.
How does JPEG compression reduce file size?
JPEG compression reduces file size by changing the colour values and blocking together groups of pixels with a more uniform colour, so that it doesn’t have to store as many different ones. While this does decrease the file size, it also alters the true image by changing the colours.
Older iPhones store photos as JPEG files. But since iOS 11, the default file type is now HEIC. You can change your preferences in the Compatibility settings on the iPhoto app.
Exchangeable image file format or EXIF, is data contained within a JPEG file that provides extra information to the user such as:
You can view the EXIF data in Windows by right-clicking on the photo. Select Properties, then Details and scroll down. To view EXIF data on a Mac, open the image in Photos and choose Get Info.
Lossless compression, 24-bit colour - PNG files are the developer’s favourite.
JPEG’s biggest rival back in the day, TIFF files support both lossy and lossless compression.
Compare these two raster files to see which one makes the gradient.
Which file format is better for capturing images in-camera?
Is TIFF or JPEG better for editing photos?
Compare JPEGs with the proprietary Adobe file format to see which is better for quality and shareability.
Want to make a JPEG smaller? Learn how to compress an image.
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