Hi all need a lot of advice please added screenshot of the leo triplet but is discoloured,so far ive used weighted batchpreprocessing with darks flats bias then dbe then done a rgb combination but the resulting image is discoloured ,i know ive took a shortcut but what would you do next thanks
Something is not right in your calibration which is causing the black spots. Pixels are getting clipped to zero. Possible causes would include offset being too low, offset in hour bias or dark frames being different from lights, gain being different between lights and calibration files, bias being subtracted twice. Lots of possibilities.
Second, after registration and stacking but before DBE you do want to apply the exact same crop to all your subs or DBE (especially with auto-placed samples) will not work properly.
Third is your actual question—the color imbalance. This is totally normal. Some combination of light pollution gradients and different sensitivities through different filters. There are two common approaches. The first is to use background neutralization and color calibration. The second option—even better—is to use photometric color calibration with background neutralization enabled.
After all this you will likely still see a green bias in the background. Use SCNR to reduce/remove it.