I will teach a course on Kdenlive for students in a course... the problem I have is the COLOR CORRECTION TOOLS.
Seems to be using Frei0r plugins, and actually I used those in OpenMovieEditor Before and most of them were AWESOME in a node editor these are some cool stuff I worked on: http://www.anubis4d.com.ar/1/mediafx/nodosOME1.html
but in Kdenlive R, G and B cannot be used to correct the video with the bright/contrast tools, and we don`t count on CURVES which is important.
In this example I splitted the R,G,B, channels and worked with curves to get a mask , then I have used the mask as a alpha channel.
PS: now if you want to FORK the node editor (since Ome is abandoned), that would be AWESOME!