Re: [Gimp-developer] Three questions about opening an image and converting it to linear light RGB


It is my very strong opinion that values should not be clamped by default.

If you are writing an operation (a "node") that is broken by negative or
values breaks, do not clamp the input and output without carefully
considering the possible impact on the entire toolchain.

Very very carefully: Clamping values can have surprising side-effects (as
the Blender community apparently discovered through experience).

If it is likely that your operation will be fed, for example, negative
values, try to write your operation so it does something sensible with them.

Clamping should be a last resort.


Of course when you are dealing with specific color spaces you may know
"what's what" and, for example, that negative values are totally
meaningless. This business is almost as messy as dealing with the fact that
colorspace handling is colored by "intent".

I wish I had figured out a simple "Always do this and you'll be fine." or
"Never do this and you'll be fine".

GIMP is too complex an application for me to be able to make such
pronouncements. And this question of "Shouldn't we clamp negative values?"
is intertwined with colorspace conversion issues, which is really difficult
to get just right in all situations without user intervention.

Layers have meaning, colorspace are linked to intent and purpose, and
automating processes based on hidden semantics is not trivial.

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