JPEG

JPEG (Joint Photographic Experts Group) is a lossy compression method  for digital images, particularly for those images produced by digital photography. The degree of compression can be adjusted, allowing a selectable tradeoff between storage size and image quality. JPEG typically achieves 10:1 compression with little perceptible loss in image quality.

JPEG compression is used in a number of image file formats. JPEG/Exif is the most common image format used by digital cameras and other photographic image capture devices; along with JPEG/JFIF, it is the most common format for storing and transmitting photographic images on the World Wide Web. These format variations are often not distinguished, and are simply called JPEG.

JPEG/JFIF supports a maximum image size of 65,535×65,535 pixels, hence up to 4 gigapixels for an aspect ratio of 1:1. The 16 million possible colors in a JPEG image are produced by using 8 bits for each color (red, green, and blue) in the RGB color space. This provides 28 or 256 values for each of the three colors, which combined allow for 256 x 256 x 256 or 16,777,216 colors. Three values of 0 produce pure black, while three values of 255 create pure white.

The JPEG compression format was standardised by ISO in August 1990 and commercial applications using it began to show up in 1991. The widely used IJG implementation was first publicly released in October 1991 and has been considerably developed since that time. JPEG JFIF images are widely used on the Web. The amount of compression can be adjusted to achieve the desired trade-off between file size and visual quality.