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

[Gez <listas ohweb com ar>]

El sáb, 05-04-2014 a las 12:21 +0200, Nicolas Robidoux escribió:

> 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.

Not even a last resort. Clamping unbounded values will destroy the
excess gamut that the unbounded transform is supposed to keep.
Blender works in scene referred linear (from 0 to infinity) and clamping
is used to restrict the values to the display-referred limits when the
user needs it.
In Blender chromaticity is never out of bounds (unless you explicitly
fed a node with an ilegal value, like a negative value), it's just
intensity. For instance, if your red channel goes beyond 1.0 it never
means "redded than red".

We agree: values should not be clamped.
My question question (and I think also Elle's question) wasn't about
whether those values have to be clamped or not, but about the impact of
values beyond the display referred bounds resulting from the forced
conversion to unbounded sRGB.

Gez.