"File formats: JPEG" configuration dialog

This dialog allows to specify parameters of JPEG file / stream format.

"Quality" slider, edit, spin boxes

These control boxes allow you specifying a quality of the compressed JPEG image.

"Color space" group box

This group box allow you to specify color space of JPEG image.

JPEG format allows to save color image in its original color form or convert color image into a gray (black and white) image. Size of a gray JPEG file is smaller than the size of a color JPEG file. Using gray image may be useful when color information is not required and size of the JPEG file has to be as small as possible for the given level of quality.

Remarks

JPEG is a lossy compression algorithm. When image is converted into the JPEG format some color information is lost. As a result a quality of the image compressed with JPEG algorithm becomes lower than it was originally in the uncompressed image. The loss of a quality depends on the level of compression. The higher level of compression in JPEG file, the lower level of quality.

Practically it means that there has to be found a compromise between quality and the level of compression acceptable for the concrete situation.

Level of quality in the uncompressed image is defined as 100%. Level of quality about 80% is considered usually as a high. Level a quality about 50% - 60% is considered as an average. And level of quality about 20% - 40% is considered as a low. These estimations are approximate, and may be different under specific conditions.