as you can see in the folowing image if you are using a white chroma, kdenlive detects that the variance between white and black is 1

http://imgur.com/fM5ykRy

hope to have news from you

Marc Astals

At the moment, I don't have a working Kdenlive installed, but a friend confirmed the problem.
I looked into the bluescreen0r code, but can't see any obvious bug - I must be kind of blind, it is a very small piece of code...

In the mean time, try "color selection"