The JPEG (JPG) File Format
JPEG is one of the most popular image formats, being used in photography, video, print, web design and pretty much every type of media production.
- Format type: Lossy image compression
- Developed by: Joint Photographic Experts Group (JPEG—hence the name)
- Used for: Still images, with a motion version for video.
- File extensions: .jpg .jpeg .jpe .jif .jfif .jfi
- Maximum pixel size: 65535×65535
- Compression performance: Typically 10:1 without perceptible quality loss.
- MIME type: image/jpeg
- Standards: ISO/IEC 10918, ITU-T T.81, ITU-T T.83, ITU-T T.84, ITU-T T.86
The Joint Photographic Experts Group was formed in 1986. The first JPEG standard was released in 1992.
JPEG files are most often used for photographs and other images that require a high number of colors with smooth variations. JPEGs are excellent for distributing low-file-sized versions of images, and for displaying images on web pages where file size is an issue. However the lossy nature of the compression means that JPEGs are not well suited for editing or archiving high-quality masters. JPEGs should never be used when an exact replica of an image is required (e.g. scientific imaging).
JPEGs do not work so well with images containing a small number of sharply contrasting colors, line art, text and similar graphical images. This type of image is better suited to PNG, GIF or any lossless format.
Example
The image below has been saved in Photoshop using five different quality settings. In Photoshop, a higher setting number means higher quality (less compression). The goal is to find the best compromise between low file size and acceptable quality. Experiment to get the best results for any given image.
Quality: 12 (Maximum)File Size: 55 KB
Quality: 9File Size: 34 KB
Quality: 6File Size: 30 KB
Quality: 3File Size: 27 KB
Quality: 0 (Minimum)File Size: 25 KB