Digital Photography Glossary

JPEG

JPEG stands for Joint Photographers Expert Group, and it is a file format for storing digital images with a considerable amount of compression. JPEG is lossy compression method and the amount of compression can be adjusted, with an inverse relationship between image quality and file size. JPEG has a standard compression ratio of 10:1 without any visible loss of image quality. JPEG is the most ubiquitous file format for digital cameras and other photographic image acquisition devices as is saves images to a small, manageable file size and is easily transmitted on CD, DVD, over the web and on websites.

Click here to learn more: Understanding Digital Photo File Formats

Joule (flash unit)

Joule describes the energy capacity of a flash unit. It has no ability to determine the amount of light hitting a subject nor does it take into account loss of electrical power from mechanical inefficiencies in the flash unit.

Jaggies

This is the jargon or informal name for digital artifacts found in raster images. These star-line lines appear where there should be a smooth straight line or curve. Jaggies appear when the output device (i.e. printer or monitor) doesn’t have the adequate resolution to reproduce a smooth line.

JFIF

JFIF (special type of JPG-EXIF) stands for JPEG File Interchange Format. It is a JPEG file encoded to be compliant with JPEG Interchange Format, and it contains image data such as resolution and aspect ratio. JFIF files have a device-dependent RGB color space.