Remove gradient

[Mauro F1]

Obervatory of Cavezzo MPC107, 10x30 sec image of M13 heavily disturbed by gradients (veils and clouds).

1) Select the area not to be included with the mask tool.
Here's how to remove them and [Smooth] ~ 15 to 20 pixel.

2) Select [Remove gradient adaptive] - [Low pass] 10.

3) Low processing.

Mauro F1