Noise reduction with Gimp. Free software!

Here’s a little noise reduction I did this morning using free software.

Here’s what I started with. Not only noise, but banded noise… Yuck.
And here’s what I ended up with. Not perfect, but better.

I lost a little detail, but I like the finished image better.

Anyone who has had to deal with banding noise knows just how difficult it is to get out. I don’t think it’s noticeable in the final image, unless you are predisposed to think it’s there because you saw the initial image.

I could have saved some of the detail, but the rewards diminish as you put more time into these. Not every photo is the work of a lifetime.

At the bottom of the post is what I did, without explanation. It’s worth imitating, because some of the tricks are useful in isolation from everything else.

It might look complicated, but these are the kinds of operations that get performed again and again, so in practice it’s like, “click, click, click, click, click,” and maybe takes 5 to 10 minutes, no more.

Best of luck with your photos.

Ctl-D to create duplicate image
Close original image, work on duplicate
Colors -> Components -> Decompose… -> Color Model LAB
Work on grayscale image
Highlight A layer in layers dialog
Filters -> Enhance -> Wavelet Denoise (Threshold 10)
Highlight B layer in layers dialog
Filters -> Repeat Wavelet Denoise
Colors -> Components -> Recompose
Close grayscale image, work on main image
Duplicate layer in layers dialog
Mode: Grain merge in layers dialog
Layer -> Mask -> Add layer mask… -> Grayscale copy of layer
Colors -> Invert
Paintbrush tool, 2. Hardness 0.50, size 250, opacity 50%
Paint cat in layer mask to remove dark parts
Edit -> Copy Visible
Edit -> Paste as new layer
Image -> Transform -> Rotate 90 degrees clockwise
Filters -> Enhance -> Destripe (36)
Image -> Transform -> Rotate 90 degrees counter-clockwise
Filters -> Blur -> Gaussian blur… Horizontal=20 Vertical=20
Layer -> Mask -> Add layer mask… -> Grayscale copy of layer
Colors -> Invert
Paintbrush tool, 2. Hardness 0.50, size 250, opacity 50%
Paint cat in layer mask to taste (switching between white and black, to taste, to remove artifacts, keeping an eye on effects)
Edit -> Copy Visible
Edit -> Paste as new layer
Use smudge and healing tool to break up banding in light area.