DBE Part 2

Images with not a lot of free background present more of a chalange, But DBE can create background models with remarkabley few samples.

Below is a image that I opened and applied the STF to and you will see that it has a gradient to the top right

I will say that flat fielding is a must with images with little free background , so DBE has as little to do possible and the image below has had a flat field applied the gradient left is due to light polution

Click image to enlarge

If you look closley you will see I have hand placed a few samples by hand, some in all four corners and others in areas with as little nebula as possible

If possible I would have liked to lower the tolerance setting , but when I did some of the samples did not carry enoughg weight ( they became red) so I left them at the default setting.

Click on image to enlarge

1) The origanal Image at top left

2) Model of background at top right with gradient we will subtract from the origanal image

3) New image at bottom with gradient removed , pretty good I think