Over on the Adobe Photoshop User to User forum the question of image degradation with JPEGs came up. One of the Photoshop wizards posted a test that actually showed how many pixels changed or were lost each time a JPEG was resaved. There were changes and loss of information with ~every~ save.
Bob said the loss would be minimal and that one would have to save several times before the loss becomes evident. That's not quite the same thing as there being no loss. However, I firmly believe some people can see smaller amounts of image degradation a lot easier than others. Once again, depending on the image details, the loss may be more or less obvious. Viewing the files @ 100%, or making large prints, will show these losses a lot more than viewing web-sized images or making smaller prints - but we all know that. You are, of course, absolutely correct that he loss exists with every save, although it's not always the same amount of loss. I think the first resave loses the most information, and subsequent saves lose a smaller percentage (based on the specific test shown on the User to User forum). The 12 figure is not the number of times an image is saved. Twelve in this case is a quality setting in Photoshop. When using the "Save As" function there are twelve quality levels at which a file can be saved, with twelve being the highest quality. Using "Save for Web" there are 100 levels of quality that can be chosen. Shel "You meet the nicest people with a Pentax" > [Original Message] > From: <[EMAIL PROTECTED]> > [EMAIL PROTECTED] writes: > True. Closing a JPEG does not alter it in any way. Saving it > recompresses the data, with commensurate loss. > > However, if you always save JPEGs at the highest quality (12 in > Photoshop) the loss will be minimal. You can resave JPEGs saved at > 12 several times before the loss becomes evident. > > Bob > ======= > Where do you get this 12 times figure? When I was working with graphic files, > admittedly not photographs, it seemed to me there was a degradation after the > second resave. > > Marnie aka Doe
