The Gimp plug-in descreen works in the
frequency domain by means of a fourier
decomposition. I think, darktable has means to
do this too, but I don't know how or if the
pixel patches aren't simply too large.
Exactly.... in commercial print - all dots are at 100% density. They are
smaller or bigger. How dense they are would produce deeper tones or not.
In addition - the color is created by CMYK inks (cyan magenta yellow
black). While the normal RAW or JPG are RGB. In addition - there are
line screens used. 133, 150, 250. Wait... this is not all :-) you have
AM screening and FM screening. And the FM screening is in microns - also
known as stochastic printing.
Each of these values contributes how descreen would work. It has to
acknowledge them and work based on these values. None of these are
applicable in photography like camera or film photography.
In my opinion - the can question (If DT can do it) - yes - if somebody
develops it. Does it work currently? no - to the best of my knowledge -
I haven't seen such. Is there a chance for it to be developed? I would
be extremely surprised if somebody does.
Surely - you can blur the image etc. But the tools in DT are not
targeted to reproduction of a printed art. A good demosaic would use the
specifics of the printed image.
And what is the use case? The most apparent one is to copy a scanned
label and print a fake one.
I don't want to be sarcastic really. I was simply exposed enough to the
industry.
Good luck with the task... If I am in your shoes - I would focus my
effort towards the GIMP plugin or if Photoshop has something to offer in
this realm.
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