Hello! This is my first post in the krita forum! I think it's a great software, thanks for all your hard work!

I would like to know if there is a way of selecting parts of an image depending on the intensity values. Darktable has the parametric masks that can work on the L*ab space. I have seen there are also some plugins for GIMP to generate mask layers depending on the luminance value.
http://www.darktable.org/usermanual/ch03s02s08.html.php

In Krita I have found the "Select from Color Range" in the Select menu, but it lacks options to define how the selection would be. You just can select highlight, midtones and shadows, but you can define whats should be consider as a highlight or how it should blend values. Also, the color selection tools are restricted to RGB values, so its not easy to define correcly what highlight, midtones or shadows are.

Also, the "Select from color range" is not available when you are using a File layer, so it's impossible to generate an image with another software, import to Krita as a File Layer and do this king of selections on the new image.

Any idea to support this kind of selection in Krita?
If there's no possibility to do this, I could try to write some patches to the "Select from color range" tool to support this, I would just need some initial help to begin working with Krita code.

Thanks all!