Quote:
Originally Posted by slayda
This is not exactly true. JPEGs are generally smaller than GIFs from the same original. GIF's are 8 bit and use a lossless compression. JPEGs can be 24 bit but, except at the highest quality which is not usually used, is a lossy compression. This can be seen if you start with a 24 bit, uncompressed TIFF and change it to JPEG and back to uncompressed TIFF and iterate on this several times. Each conversion to JPEG loses a little and it accumulates.
On the other hand, if the original is 24 bit then the first compression to GIF loses 16 bits of color resolution.
Bottom line - if you start with an 8 bit image then GIF is better and if you are iterating in the compression of a JPEG, it is bad. But for a single compression of a 24 bit original, JPEG can be better quality and usually results in a smaller output file.
Maybe more than you wanted to know about GIFs & JPEGs.
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You do not lose 16 bits of color resolution in converting to Gif. What you lose is a limit to the maximum number of colors that can appear in the image which is limited to 256 different colors. The colors themselves are defined in a palette that is 12 bits I believe so it supports 4096 different colors.
Dale