Question about lossless formats

Archived from groups: rec.photo.digital (More info?)

If I start with a picture and save to a lossless format (say TIFF), then
save the TIFF to another lossless format, say PSD, then save to another (say
JPEG 2000) etc, etc. Then I resave back to TIFF at the end (I've made no
alterations or modifications). Is the final file identical to the one I
started with (or has it changed and how?) Is it worse or degraded somehow?
All I do is save in a circle (through various lossless formats) and come
back to the original format. Any opinions appreciated.

Archived from groups: rec.photo.digital (More info?)

If there is any loss it will be when you save the image as a jpeg, but
depending on the compression setting you used (in PhotoShop a higher
compression number is better quality and a jpeg larger file) you may
not be able to see it.
I have a very hard time seeing any deterioration unless I set the
PhotShop jpeg compression to 3 or below

Archived from groups: rec.photo.digital (More info?)

Unless you have gone from 16-bit to 8-bit somewhere along the way.
Some programs will happily read a 16-bit file and can only save as
8-bit, so the term 'lossless' may be a little misleading....

Archived from groups: rec.photo.digital (More info?)

"larrylook" <LarryLOOK@noemail.com> writes:

> If I start with a picture and save to a lossless format (say TIFF),
> then save the TIFF to another lossless format, say PSD, then save to
> another (say JPEG 2000) etc, etc. Then I resave back to TIFF at the
> end (I've made no alterations or modifications). Is the final file
> identical to the one I started with (or has it changed and how?) Is
> it worse or degraded somehow? All I do is save in a circle (through
> various lossless formats) and come back to the original format. Any
> opinions appreciated.

It'll be identical, if you *really* don't change anything. Don't
change color space, don't change bits-per-pixel, etc. And with TIFF
for example, there are many compression options possible according to
the standard, including some lossy ones; and of course if you choose a
lossy compression method in that situation then all bets are off.
Same with Jpeg-2000; I do seem to remember a lossless option in there,
but *most* jpeg-2000 files use a lossy compression.
--
David Dyer-Bennet, <mailtod-b@dd-b.net>, <http://www.dd-b.net/dd-b/>
RKBA: <http://noguns-nomoney.com/> <http://www.dd-b.net/carry/>
Pics: <http://dd-b.lighthunters.net/> <http://www.dd-b.net/dd-b/SnapshotAlbum/>
Dragaera/Steven Brust: <http://dragaera.info/>

Archived from groups: rec.photo.digital (More info?)

In article <kMidnc1-xpoDwsXfRVn-rA@comcast.com>,
"larrylook" <LarryLOOK@noemail.com> wrote:

> If I start with a picture and save to a lossless format (say TIFF), then
> save the TIFF to another lossless format, say PSD, then save to another (say
> JPEG 2000) etc, etc. Then I resave back to TIFF at the end (I've made no
> alterations or modifications). Is the final file identical to the one I
> started with (or has it changed and how?) Is it worse or degraded somehow?
> All I do is save in a circle (through various lossless formats) and come
> back to the original format. Any opinions appreciated.

Do you have PhotoShop? If so, try your experiment and report back here
what your results are.