What is the difference between TIFF files and JPG files? They are different ways of storing images in a pixel or raster format. Some important information:
Pixels – picture image element
Image resolution – number of pixels in a digital image (higher resolution, better quality)
Monochrome image – each pixel is stored as a single bit (1 or a 0). A 640x480 monochrome image requires 37.5 KB of storage.
Gray-scale images – each pixel is stored as a number between 0 and 255. A 640x480 gray scale image requires over 300KB of storage.
8-bit color images – Each pixel is represented by 1 byte. 256 possible colors out of the millions of colors possible. A 640 x 480 24-bit color image requires 307.2 KB of storage. Requires a color lookup table.
24-bit color images – Each pixel is represented by 3 bytes (e.g., RGB). 256x256x256 possible combined colors (16,777,216). A 640 x 480 24-bit color image requires 921.6 KB of storage.
Some standard system-independent formats
GIF – Graphics Interchange Format. Designed initially to transmit graphical images over phone lines via modems. 8-bit representation (256 colors). Suitable for images with few distinctive colors. GIF works well with images that have only a few colors such as line drawings.
JPG – Joint Photographics Experts Group. Compresses either full-color or grey-scale images. Works well with photographs, artwork, etc., but not well with lettering, simple cartoons, or line drawings. JPEG compression takes advantage of the limitations in human eyesight to make the image represented smaller without compromising what we see as humans. Basic jpeg stores images with 8 bits per color (24 bits for RGB, 8 bits for grey scale).
TIFF – Tagged Image File format. Stores many types of images (monochrome, gray scale, 8bit and 24 bit RGB)
(For some good information on the various graphic file formats, see page 29 of the @OIT Fall 1999, Vol 5 #1, and also the @OIT Spring 2000 page 13 on .jpg compression.)
See also www.cica.indiana.edu/graphics/image.formats.html for information on various types. Wikipedia provides excellent review of image formats