An unanswerable question as posed. Some rough info:
Compressed how? TIFF compression is limited, but lossless, so there
would be no deterioration.
Compressed how much? JPEG compression involves loss of information. But
JPEG compression is adjustable from very high compression, with great
loss of quality, to modest compression with essentially no visible
quality change. At any given level of compression, the actual reduction
in file size depends on the content of the image. The difference in file
size from one end of the range of compression to the other is quite large.
JPEG2 involves noticibly less image degradation at a given level of
compression, but is far less common, probably because the developers
want royalties.
PNG is also a lossy compression tool that's supposed to be pretty good,
at least for web images, but I don't know anything else about it.
What do you mean by 'photo quality'? What medium, what size? What are
your criteria for quality, and how do they compare to mine and others?
It is quite clear from posting and comments on the list that images that
are great technical/photo quality to some are junk to others.
I don't have the answers to most of the myriad combinations, but know
enough to know it isn't an easy question with a simple answer. I think
you pretty much have to experiment.
Moose
Gregg Iverson wrote:
>Has anyone done a comparison of photo quality after compressing for
>e-mailing vs. the uncompressed file? I don't remember a discussion of this
>topic, although I have been off the list a couple times over the past four
>years
>
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