Re: [Gimp-developer] Don't make an architectural mistake based on a groundless premise

[Simone Karin Lehmann <simone lisanet de>]

> Am 07.10.2014 um 12:27 schrieb Øyvind Kolås <pippin gimp org>

> The set of pixel formats currently in babl are by
> implementation&definition references to unchanging color spaces and
> representations - this is how babl is built with linear sRGB as it's
> connection space; and this is how ICC works with XYZ as it's
> connection space.  

Your comparison is not valid, and you know that. In babl/unbounded sRGB world your input space and output 
space differ in a very important aspect to the PCS space unbounded sRGB: unbounded sRGB can have values < 0 
or > 1, input and output don't. Whereas in ICC / XYZ world input, output and PCS have well defined 
boundaries, namely 0 and 1 and well defined clipping, so everything is 0 <= x <= 1. The interesting point is, 
that the math really differs between your world "unbounded sRGB, no clipping" and "defined boundaries, 
clipping". You've already encountered one main difference: multiplying negative values makes no sense in 
respect to color. Well, now think of adding pure white to pure white in your babl / unbounded sRGB world: 
what's the result? Unbounded-sRGB-double-pure-white? And if you substract pure white from this double-white? 
What do you get? 

> Elle writes well and seemingly with pleasure. Personally I prefer
> writing documentation to writing email, but neither of those are
> pleasurable like writing code. You can however take my word for how
> babl and GEGL works

I'll take your word and I'm quite sure you know how babl and GEGL work. But that does not mean, that they 
work correctly. And, although I take your word, I'd like to ask you again to give mathematical proof and 
equotations to prove your statements. Elle does, you don't. And this has nothing to do with how babl or GEGL 
work nor whether writing documentation or coding is more pleasurable. It's about giving mathematical proof of 
statements. And as far as I have read about this topic, you are the one that only gives words, not code nor 
equations.

BTW, I've changed the subject back to the original one.

Kind regards
Simone