--- "Pat Cullinan, jr." <[EMAIL PROTECTED]> wrote: > I had been a believer in the proposition that multiple jpeg saves > would > degrade an image, but after reading a notice to the contrary in one > of the > trade mags, I did my own trials and now I save and resave jpegs which > aren't even maximum quality without any qualms.
The trade magazine is wrong at least for the following common scenario. If you save a picture as jpeg in PS, close the image, reload the image and save the image again in jpeg you will lose data. The difference noise like and very small. For a normal picture you won't see any difference. Also it might be the additional loss gets smaller and smaller with many additional savings (without editing) upto a point where there is no change anymore. I have no mathematical proof for that, though. Now if you start with an image in PS, edit it, save it, edit it, save it, etc. you are not losing any data. The reason is that PS only writes the compressed image to a file but keeps the uncompressed image in memory. So it does not compress it and then reload the compressed image back into memory. In the later case you would lose data with each save and it would be awfully slow. One thing I wonder is if it is possible to do a lossless flipping of an image that has not a multiple of 8 pixels in the direction you flip it. Does anybody know about that? Robert __________________________________________________ Do You Yahoo!? Send FREE Valentine eCards with Yahoo! Greetings! http://greetings.yahoo.com ---------------------------------------------------------------------------------------- Unsubscribe by mail to [EMAIL PROTECTED], with 'unsubscribe filmscanners' or 'unsubscribe filmscanners_digest' (as appropriate) in the message title or body
