RE: [PRODIG] PS7 .jpeg resave

[Robert McClory]

Douglas Burns wrote:

I've just tried this from PS6 and the results do surprise me! I can see not
a single difference between the two images; the file sizes are identical
too.

This doesn't make sense to me, but I've tried the exercise twice and get the
same result. Is this a bug in PS or is it supposed to happen (or have I
screwed up the exercise?)

Actually, unless I screwed up the exercise (possible), and therefore also misunderstood Mr. Evening's intent, you should (and I did) get one image, the 10x resaved, that has noticeable artifacts forming in areas of contrast. I know there have been tests done that claim no discernable difference between files saved max quality .jpg several times and the original. I have done such tests myself in the past to determine the feasibility and client acceptance of compression for prepress workflow purposes. It seems, however that resaving at medium or low compression should yield undesirable results, as it did in my tests. Maybe Mr. Evening could throw his two cents in on the overall issue of .jpg compression and set the record straight. I thought the issue of .jpg compression/image quality was pretty cut and dried (and well explained in the Photoshop manual since version 3 when I first used it, not to mention, I'm sure, Martin's book which I have on order set to arrive any day now) but it seems as if there is discussion to be had so lets have it.
Again, this debate was not intended but...

Also, the one valid reason for resaving .jpgs to .jpg that I should have stated in the first post is for the generation of web images. Maybe that would have reduced the rash of "agggghh, don't do that posts." Sorry.

Thank you,
Robert

P.S. Has anyone else seen image corruption when resaving D1X .jpgs to .jpg from PS7?

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