Question about lossless formats

[Guest]

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.

 

[Guest]

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

 

[Guest]

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....

 

[Guest]

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....

 

[Guest]

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

chrlz@go.com wrote:

> 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....

Some editing programs don't save the EXIF data either.
Losing the EXIF could be considered a loss.

 

[Guest]

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, <mailto:dd-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/>

 

[Guest]

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

>
> 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.

In Elements 3 when saving in JPEG2000 there's a box to select if you wish
for lossless compression.

 

[Guest]

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

larrylook 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.


Hi...

It will be identical.

Ken

 

[Guest]

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.

 

[Guest]

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.

What would you want to do that for? Look, save as a PSD or whatever,
burn to CDR or DVD. Fiddle with the copies still on the pooter and if
you screw up you still have the PSD on disc. Enough of this What if...