Quick question for any of you model on a white background shooters.

I've been doing some series of shots recently of models (me) on a white background, all's been going well till I had a rejection on iS because of rough edges, strange I thought so went back to view the file, they were right!

However this is where my problem is, the tiff file is absolutely fine, perfect figure hugging marching ants. Yet when saved as a jpeg for some reason on some of the files the ants are wandering, now the annoying part is that I took the jpeg file in question and corrected it so they were tight again, saved it but when I opened it up to check they'd gone a wandering!!
Furiated I did the whole process over again starting with the tiff file, but the same problem happened, now the most annoying part, it's not doing it on all the files from a series, all using the exact same processing methods.

I've seen this mentioned once or twice before on forums but can't find the threads now.

My eyedroppers are all set to 255, I'm saving the jpegs at 12 and like I say the tiffs are fine.

It's not a major problem as I'm only talking about one or two stray pixels and to be honest you only notice it when at 100% using a 0 tolerance with the magic wand, but it's bugging the hell out of me.

Any clues anybody?

Thanks

Richard

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Richard

I've seen this answered on forums as well, but like you, I can't remember where.

I think the answer was that it's something to do with the jpeg algorithm - some of the white pixels near the edge of the coloured subject are being altered during the compression process. That might explain why the problem reappears after you've saved the corrected version, because you're running the jpeg compression over again each time you save.