[Gimp-user] Luminosity Masks

[Rustbucket <forums gimpusers com>]

I have been trying to get to grips with luminosity masks for a couple of months
now  -  on and off.  After reading the Gimp tutorial and watching a couple of
You Tube vids I think/thought I understood them  :-)

On a photo where I wanted to lighten the darker bits I produced a set of
luminosity channels ie L, LL, LLL D, DD, DDD  all went well and seemed to be
working.   I took the DD channel and produced a layer mask with the idea of
lightening this part of the image.  My problem, which has me tearing what hair I
have, is that -  when I apply increasing the exposure, or lighten or darken
modules, from the colour tab, while it lightens it also introduces a colour cast
!   And further to this if I then try to turn the photo into a Mono, the colour
cast still remains although the original photo turns mono.  I have thought about
this and tried whatever I can think of, nothing has worked and I am at a
complete loss.

Hope I have explained my problem well, I have run out of ideas and would be
grateful if some knowledgeable person could point me in the right direction.

Best Wishes  -  Jn

-- 
Rustbucket (via www.gimpusers.com/forums)