I will have to run some test on this, but as far as I know the CPT format
is lossless, I have never had any issues with that one. I'm not sure about
the CDR format and JPG bitmaps, I would not assume that this is lossless
since your files are JPG. I'm not sure if I follow your procedure exactly,
but anytime you open a JPG bitmap for editing in PP or Draw there will be
some loss of data. That is probably why most of us use TIFF files when
working in Draw. I'm not totally convinced that what you are showing in your
pictures are compression artifacts. I wonder if your Color management import
export settings are correct, perhaps you are converting the image between
different color spaces every time you save and open an image?
--
Jewelry By Alfred
www.alfredky.com
"Sean" <azurepicTHISISFORSPAM@yahooSPAM.com> wrote in message
news:47dffe63_2@cnews...
> Is the CPT file format truly lossless?
>
> I have noticed over the past couple years with PP and DRAW 12 and 13 that
> color blotches, often magenta but others as well, seem to 'appear' in
> photos
> that have been retouched and saved a few times. The photo is usually
> saved
> in the CorelDRAW file and sometimes edited in PP through the 'edit bitmap'
> link. I have at times had to go back to the original photo and start over
> as these blotches became prominent.
>
> I know that adjusting levels and contrast and so forth will change a
> photo,
> but these blotches are not usually obvious until the file has been saved
> and
> reopened later.
>
> Today, after losing time dealing with this again, I did a test. The
> before
> image attached is a straight crop out of a photo saved from PP as a CPT,
> making it our control subject. I then put it in DRAW 13 and saved,
> closed,
> opened, moved bitmap, saved, and closed about 10 times. The after image
> was
> opened in PP via the edit bitmap button from DRAW and saved as a jpg from
> there, and the before jpg also saved with identical jpg settings.
>
> No color edits or levels or changes were made. With lossless compression,
> these two images should still be identical, no? Take a look at the middle
> of the back tire and compare the images close up.
>
> So, wondering if I should post this in only the DRAW thread instead, I did
> the same experiment in PP. Open, draw mask, remove mask, save (that
> should
> be a lossless operation, but you could try something else though I don't
> think it matters what you do, it is the saving), repeat. The result if
> anything is even worse, as attached 'afterpp'.
>
> You are welcome to try it yourself. Does anyone have an idea of why this
> happens or if there is a setting that is associated with it? I am
> seriously
> worried as I always trusted CPT files for lossless compression and
> unlimited
> saving.
>
> Thanks,
>
> Sean
>
> PS: Only cross-posting this because it truly affects both DRAW and PP.
>
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