M81, M82 help

[Geno]

Since getting my DSLR I have been trying to get some DSO pictures and have been quite impressed with M42, M31, and M45 but nothing special.

I managed a few subs on M81 the other night which has impressed me more than anything but unfortunately there is a weird glow. The moon had come up and I think some light pollution.

Anyone any ideas how to remove this in Photoshop

I know it's not a brilliant image but the clouds have been in a while and I wanted to get something more out of this.

[dlp]

Hi Geno, well done for getting an image of a difficult target!

I'm no expert but I can tell you you've got (1)light pollution (2)gradients.

The former can be mostly cured by using a light pollution filter at the time of taking, and the latter by taking 'flats' (loads of threads on SGL on both). You should also be taking 'darks' for noise removal. If you do a really OTT histogram stretch in PS, you will see what a bad effect these are all having on the image, but without seeing your original unprocessed stacked image it's difficult to say whether they could be removed. I can say that I had a try with your jpg in PixInsight and struggled.

Onwards and upwards - it's all a big learning curve, but you're learning all the time you're doing!

David

[Geys1987]

You can correct it a bit in Photoshop by using a layer with just the information about the gradient. Copy your image in a new layer and apply dust&scratches to it. Then clone the remaining bright object away. Last step is to substract this layer and play a bit with the sliders until you have something that looks good for you.

Here's my attempt with this technique.

EDIT: you can see some banding in the image but I think it's the result of using a jpeg as starting image.

[carastro]

This looks to me like vignetting which can be removed by taking flats.

Carole

[Geno]

Thanks all.

Will have another go at it with the LPF fitted if the clouds ever go away