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yellowish vertical bars across scanned image
#1
Hi guys,

I am really struggling to get rid of the yellowish tint across this scanned image - seen as vertical bars going through different areas. I was trying to use Fuzzy select tool, Free select tool + all options under Colors (Temperature, Curves...) but I need more knowledge. What is the way to sort of replace certain color spectrum (in this case yellowish pixels) whilst not affecting the other parts of the color spectrum - I mean so that I do not end up with areas contrasting with the rest of the image. Basically how to get rid of the yellowish part of the color space in those vertical bars and no more?

Thank you.

https://i.imgur.com/LG5UDkO.png
https://i.imgur.com/R7cg4k9.png
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#2
If the pattern is regular and really due to external causes

- extract the bands from a part of the image where they happen on pure white
- make layer where you recreate the bands on a white background
- put it in "Divide" mode over your image.
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#3
It's a little tricky to solve this problem because the yellow line becomes more saturated from the middle. I've tried this :

1/ load picture
2/ make a new layer (transparent)
3/ draw a yellow line (use pencil / width 4) on the last layer (in the middle of the yellow line on the picture and from the top to the bottom of the picture)
4/ blur the yellow line on this layer so that the result is as wide as the yellow line on your picture
5/ set this layer mode on 'LCh Colour'
6/ open on the gimp menu : Colours / Hue-Saturation and play with the sliders

I think you have to do this wit different layers because the difference in saturation from the middle and do this workflow on 3 different layers from the top to the kite form, then the kite form and then the area under the kite form.

My result, there is still a little yellow in the middle of the kite form, but it must be possible to get rid of the yellow by using the Hue-Saturation tool.

   
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#4
Dear denzjos,

Your trick works well with the cactus. Overall I was trying to use the new layer in LCh Hue mode and redraw the areas with Paintbrush but only your trick with the yellow line seems to work on those plants. Thank you! Also some areas are so "damaged" that I ended up cloning / healing rather then changing Hue / Saturation.
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