[Cin] Some tests on blending

[Andrea paz]

> I wonder how other software solves it ....

I can't answer that. I think the best possible is DaVinci resolve's
Color Management, but they are unattainable levels for anyone. You can
see their manual from p. 215 to p. 250:
https://documents.blackmagicdesign.com/UserManuals/DaVinci_Resolve_19_Reference_Manual.pdf

> In some sense I think we are much more OG opensource/libre/community software, not piggybacking on big corporate codedrop/development, but few cares about that ...

I, too, think that Stalmann's Free software is dead and that Open
Source managed and supported by big companies is now predominant
(Linux Foundation). Just look at the success (I think deserved) of the
Rust language, which is replacing other languages, however with the
side effect of eliminating all GPL licenses in favor of MIT and Apache
licenses (they have now remade the GNU core utils in Rust). Praise to
CinGG (and you few contributors) who still follow the beautiful idea
of GG and Phyllis!