It was 2/12/02 7:24 pm when Martin Evening wrote: > Many years ago someone on a Photoshop mailing list > reported how he had kept resaving a JPEG over and over again and > couldn't see any worsening of the image.
Erm, Martin, it could've been me. <G> I remember advocating the use of full quality JPEGs for transferring data. As a test, I saved and resaved a JPEG and noticed only a few pixels shifting and then only if I ran the pointer over it and looked at the Info palette or viewed the difference layer at something like 1600%. I was learning Photoshop then and I'm pretty sure someone on the list suggested running the pointer over the image when I couldn't see any changed pixels visually. As usual, threads have a way of wandering and what I thought was hypothetical workflow was introduced into the discussion: namely, in-house users changing it and then resaving whereas the original thread, I'm pretty sure, was about opening and resaving a JPEG. I thought then as I do now that it's better to be aware about the advantages of using a full quality JPEG. Lots of people think of it as an inferior format to TIFF because of the compression artifacts that they've seen. But when kept at full quality, the advantages far outweigh any disadvantages. Coincidently, when the thread was raging, I had just received a CD full of CMYK JPEGs saved at full quality from a film festival. I resaved the images we wanted to use as TIFFs, laid them in the magazine and never encountered a single problem. Imagine how many CD's they would've had to send if the images had been saved as CMYK TIFFs! I think I also challenged people to spot the difference visually between a TIFF saved as a JPEG, reopened and saved at full quality some 10-20 times and then comparing it with the original TIFF. I don't think anyone took up the challenge. > It was pointed out that in a > real world situation, a user would more likely open a JPEG, and make a > curves adjustment, resave. The same user might reopen and crop the > picture this time. That sort of workflow will lead to disaster. Sure but it's probably the same designer who blurs the channels of a TIFF. He does get around a bit. Wish I could earn half his salary. I'd be living in a palace on the moon by now...OK, at least in a house in Islington! <G> --/ Shangara Singh http://www.e-pixel.co.uk Adobe Certified Expert ~ Photoshop 7.0 PortfoliosOnCD for Photographers http://www.portfoliosoncd.com =============================================================== GO TO http://www.prodig.org for ~ GUIDELINES ~ un/SUBSCRIBING ~ ITEMS for SALE
