Problem with KisAbstractColorspace::difference

[Cyrille Berger]

Hello,

I have to problem with the current implementation of 
KisAbstractColorspace::difference :

1) he doesn't work at all in CMYK, try do draw a circle, and then to fill it, 
whatever threshold you choose you fill the entire image

2) I am a little bit confuse, in RGB I expect White and Black to be the two 
most differenct color, and so I expect difference(White, Black) to return 
255, but it return only 100, while difference(Blue, Yellow) return 255, which 
I find normal (it's even worse in Grayscale as you don't have blue vs 
yellow).

-- 
--- Cyrille Berger ---