Re: Book Chapter Ballooning in Size

[Bill Briggs <web@xxxxxxxxxxx>]

At 7:43 PM +0200 14/08/00, Thomas Michanek wrote:
>JPEG is a format made for realistic images, like photographs, with
>smooth color transitions and without sharp edges. Screenshots are
>generally saved more effeciently by using a format such as GIF
>(limited to 256 colors), TIFF or PNG.

It's even worse than the nuisance of increased size. JPEG compression uses an algorithym to compress the image and then recreate it, which will cause nasty "fuzzing" of high contrast edges, the like of which one finds in screen shots (it's not a lossless compression technique). 

As Thomas says, JPEG is for "continuous tone images", like photos, and GIF will not cause the problem as it is a "dictionary based substitution technique that are lossless". I always use LZW compressed TIFFs myself, and so far have never had a bad experience with them. They too are compressed without loss. JPEG for screen shots is a really bad idea. 

When people on the two FrameMaker lists complain about fuzzy graphics in PDF files, it's often because of JPEG compression. 

- web



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