Why is my gif so grainy? OMG NERD SPEAK INC!
Because of the design of the file format there had to be some limitations of colors. Formats like JPG label each pixel with a 24bit value whereas GIF only allows for 4bit index relating to a pallete. GIF strictly requires Indexed Colors Palettes where as other formats like TIF and PNG adhere to it but do not require it.
Indexed Color Palletes - any set of 256 colors from the 24bit color set.
So when you create your gif images you can use ANY colors you want, however when all is said and done only 256 of the colors used to create the image will be saved. Different gif programs handle the color selection differently, photoshop works of tone settings, most used colors and closest index matching to create its the palette. Older gif programs would let you see the color pallete at any time, i don't know if photoshop lets you create a color palette.
Anulien ~ I know you shouldnt *have* to, but for those anal about grainy gifs and <3 their PNGs... why not?