Digital Image Basics for non-Photographers • Blaise Tobia

Other image file types.

The most common and universal non-compressed file type is TIFF.

TIFF (or TFF) files maintain full resolution and full color without compression.
Files may be modified and re-saved endlessly without deterioration.
TIFF format can maintain layers and can maintain extra-depth color. JPEG can't handle either of these.

Note that there is a compression option for TIFF - LZW - which compresses less than JPEG and is considered lossless.

Photoshop file format (PSD) is also very common and becoming nearly universal.

It is very similar to TIFF but doesn't have an option to avaoid compression (a lossless compression similar to TIFF's LZW).
Besdies layers, it can preserve numerous special kinds of data created by the Photoshop application,
so it is good to keep images in PSD format if you plan to open and change them in Photoshop.

GIF is a specialized file format seen in Web pages and games.

It does not maintain full color (having a maximum color palette of 256 colors).
It is most often used for graphics and animations.

Note that image file "type" or "format" only has meaning in terms of saving images (e.g. to a drive).
Images that are being looked at or worked on, in Photoshop or other applications or a browser, have no format.
They are simply images - held in the computer's RAM and displayed on its screen.


Most calls for images specify JPEG unless high-quality files for printing are required, in which case TIFF is usually specified.