Dreamkatcha looks at JPG file formats

There’s a great website called Fileinfo.com. It is a one-stop reference point for common and not-so-common file extensions. Every file format from JPG to TIF and D64 (the last named format being the Commodore 64’s disk file format on the slow 1541 disk drive). Inspired by this website is our look at the file formats you come across. For the first article in this series, we look at the JPG file format.

The first version of the JPG file formats was released on the 18 September 1992. Back then, we were dabbling with Amiga 1200s; some of us at school used BBC Master System and Acorn Archimedes computers. At home, Commodore 64s, ZX Spectrums, and Amstrad CPCs were popular with younger children (whose elder siblings bought Amigas and Atari STs).

JPG or JPEG?

The most common file extension is .JPG rather than .JPEG, though they represent the same file formats. The three (or four) character file extension is an acronym of Joint Photographic Experts Group. It is the most common image file format used on countless websites. It supports a resolution up to 24 bits, but has one limitation: its lossiness.

When a file format is lossy, the resolution degrades if an image is expanded beyond its original size. For example, an image measuring 640 x 480 pixels, expanded to 1280 x 960 pixels will have fuzzy image quality. Expanded up to 2560 x 1920, your image would look like something from Pages From Ceefax (albeit with 16.7 million colours and similarly chunky pixels). With a JPG image, anti-aliasing is necessary for smooth lifelike images.

It is by far the most popular image file format, used on many smartphones, digital cameras, and websites. JPG came of age in the late 1990s, when the file format’s light footprint was seen on countless websites. Still to this day, it is Top Dog.

Dreamkatcha, 20 June 2017.

JPG graphic image by Jane Kelly (via Shutterstock).