[Cin] possible patch for x265 on cmake 4.0?

[Georgy Salnikov]

On Thu, 3 Apr 2025, Andrea paz wrote:

> Unfortunately you are asking precise things that I am not able to
> answer. Looking at the plugin code (I understand it much less than
> Andrew, practically 0) I saw a part where it uses 8- and 16-bit
> integers and uses floats for RGBA-FLOAT. It just seems strange to me
> that the Color Space plugin, which as you say should not be about
> clipping, shows clipping with the two Blender Program test you wrote.
> However, the only difference is putting a sentence, in the manual, in
> the description of the plugin; it is certainly not something to waste
> time on.

I mean, the coordinate system of some colorspace, and the equations to
transform one coordinate system to another, may be defined not between
-infinity and +infinity, but inside some range. Like, for example, the
mathematical arcsine function (real, without an imaginary part) is defined
between -1.0 and +1.0 and not defined for, let's say, 1.25. Likewise, the
Hue coord of the HSV space is defined between 0.0 and 360.0, and saturation
between 0.0 and 1.0 (what btw should a saturation = 2.0 mean after all?).

I mean, we should firstly look at the equations defining the source and
target color spaces, namely, in what range are their definitions. If, let's
say, one space is defined 0..255, the other 16..223, then it can be
questionable, what equations may we implement outside the range where we
have standartized equations?

I mean, the question why does the color space plugin clip values, can
actually appear totally meaningless, i.e. the equations with removed
clipping may cease working outside the defined range anyway. So removing
clipping call can be insufficient, one has additionally to extend the
transformation equations to the extended range.
_______________________________________________________________________________

Georgy Salnikov
NMR Group
Novosibirsk Institute of Organic Chemistry
Lavrentjeva, 9, 630090 Novosibirsk, Russia
Phone   +7-383-3307864
Email   sge at nmr.nioch.nsc.ru
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