Ola todos
TLDR : you should be able to understand by reading bold text only 
First, let me say I bought Pixinsight 2 days ago, after the trial period. And i'm quite happy with this !
I started this hobby last december, I'm on a low budget, but I have to say, this is a damn good software ! great work, could not do without it now. Thanks for this.
Now
i've had some problems with some of my stacked images (after all calibration) the results had a greenish vignetting, that was sometimes here, always almost the same, and sometimes not.
So i've been puzzled for quite some time before realising yesterday that it was
when I used a cheap (actually not THAT cheap) CLS filter (i live in town...) that i had those
green halo.
shot with : Canon 1000D, Newton Astrograph 150/600 -> f/4
OPTOLONG Telescopes CLS Clip filter
often 240 seconds subs
See here :
What do you think, could this be it ? a bad filter not filtering uniformely ?
I'm definitely not using this filter again alright BUT, i was thinking since i have the best software for this in my hand, as wel as darks & flats & bias. That maybe i could sort this.
So first (during the 45 periods trial) as a noob, i tried to solve this with the great background extraction tools... but well, on big nebulae like rosetta neb, well it doesn't work well cause the nebula is everywhere, and i could not do without alterate it. So i had some results, but I'm sure it's really below what i could do.
Correct me if i'm wrong, but the flat are used only for "lightness" if i understood, that's why the "color" of flats does not matter, we finally divide the Light with a normalized flat. (and all the correct calibration before all right but i think we can ignore this here.)
So my flats are correcting perfectly the vignetting effect, good...
But I was thinking, if this green thing comes from the filter, and i shot my flats with the filter, then
surely, the "gradient in the filter" that would cause this is somewhere in the flat right ?So
how could I extract this, and then ... well subtract/correct this from my light ?
I was thinking right now (but did not tried yet) :
-correct the "rgb-flat" with the normalized flat ? as if it was a light frame ?
-I would obtain a "flat" containing no more vignetting data, but only color data ? the green halo ?
-substract it from stacked image maybe
-since the color will probably won't be good anymore, use photometricMagicCalibration
That's where i need some help, i don't know if that would work, and i'm thinking pixel math will be of some help here, but even simply applying a flat to a L seems not as simple as i thought.
L / F -> not good.
So maybe some basic sample pixel math expressions would help me better understand, but i could not find some...
Or just some rightly ordered process to apply different files would be of great help !! i'll find the time to fine tune this but i need help to have a better picture of what to do.
here are some files in case someone has some free time 
contains master bias,dark,flat, light, and a light frame :
bias-BINNING_1.xisf
dark-BINNING_1-EXPTIME_240.xisf
flat-BINNING_1.xisf
L_0018_ISO400_240s__26C.CR2
light-BINNING_1.xisf
Thank you !
chboing
