[Cin] Again on plugins in floating point (HDR)

Andrew Randrianasulu randrianasulu at gmail.com
Sun Dec 3 13:16:56 CET 2023

вс, 3 дек. 2023 г., 11:41 Igor BEGHETTO via Cin <cin at lists.cinelerra-gg.org

> Sorry, I didn't have time to test anything and I don't know if I can see
> something on my screen because it is set/calibrated to sRGB only.
> I think the question could be,... would the changes for clipping in the
> plugins'code would be compatible with our old projects?

Well, I think it willbe hard to answer this without actual testing? I guess
old projects ( I hope those changes only affect rgb(a) float projects) were
build around this limitation in some way - because visual result of
clipping is pure white area - something you hardly can miss. Now, more
complex layer modes definitely should be affected - but not sure yet how
normalization happened on video encode (where encoder  await 8-10 bit per
channel integer data).

So, only testing might tell ....

But in general current situation is not pretty, input information can be
lost irreversibly (even if only for exr/tiff) and internal calculations
easily can go into "everything is unrecoverably white" territory ... {sure,
you can just undo all effects, no input media is affected, but this is IMO
bad surprize for anyone who come to cin-gg especially for floating-point
workflow. I guess it was just  simplest/most speedy solution, that can be
done at each pixel individually, instead of de/re-normalizing whole array,
too bad it was discovered that late ....}

I think there is possibility to creatively use even this - but I think we
at very least should provide patches and big enough warning in project
section of manual.

> Il 01/12/2023 21:59, Andrea paz via Cin ha scritto:
> > Thanks Andrew; you and I have already talked about this at length, I
> > hope there is someone knowledgeable enough to go through the Histogram
> > Bezier code to find out how to overcome the "0 - 1.0" range. Another
> > important (but probably even more complex) thing would be to be able
> > to get your patches to work for the X11-OpenGL driver as well, which I
> > think is the most widely used.
> >
> > Speaking of patches, can I ask you the favor of creating a patch that
> > encapsulates the changes to histogram.C and color3way.C? A patch to be
> > installed with "git am ..." (with a .patch extension). I am doing a
> > lot of builds and it is tedious for me to edit the code manually.
> >
> > Finally, a consideration. Without your patches the RGBA-FLOAT color
> > model is almost useless with plugins because it allows unclipped
> > calculations only for Gamma and Blue Banana. With your patches almost
> > all plugins work in floating point (even Videoscope, without the
> > "smooth" option); only HistEQ and Histogram Bezier remain excluded. So
> > I think your patches are an important addition to CinGG. Do you think
> > it's better to try to make an appimage with your patches so that
> > others can test them, or can we put them directly into git, since I've
> > done a lot of testing by now without the slightest problem?
> >
> > Phyllis, what do you think? IgorBeg, Terje, Pierre and everyone else;
> > what do you think?
> --
> Cin mailing list
> Cin at lists.cinelerra-gg.org
> https://lists.cinelerra-gg.org/mailman/listinfo/cin
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