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Remove selective cast/stain
#1
Hi all Smile

I'm looking for ways to remove selective areas of red stain/cast on an image.

I can remove an overall red cast using inverted average colour but short of converting to B&W (using the undamaged red channel) and recolouring or cloning areas I can't figure out a way to do this.

A thought was using channels somehow, maybe as a mask, as the red channel has no damage, green and blue do.

Here's an image with the general red cast removed on the left and the remaining stains on the right.

[Image: iyf5njyl.png]

Any help appreciated!
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#2
Tried a few things with little success.

You might have to bite-the-bullet, go 'artistic' and recolorise.

Using gmic plugin http://www.gmic.eu
desaturate, a little touch up
paint in a colour map
apply
[Image: 44CqJHn.jpg]
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#3
Good try that...I can't seem to get the filter to work - I have a B&W image as bottom layer and a colored top layer but not merging the two..... any ideas?

I tried wavelet decompose and tidied up the colour residual image with some success.
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#4
(06-29-2017, 04:50 PM)The_JinJ Wrote: Good try that...I can't seem to get the filter to work - I have a B&W image as bottom layer and a colored top layer but not merging the two..... any ideas?

I tried wavelet decompose and tidied up the colour residual image with some success.

Not something I use very often, so I usually have to fiddle around with it.

Although it says B & W the image obviously has to be in RGB mode.
then it is set up like this: http://i.imgur.com/rLhrbI8.jpg - all layers - bottom (desaturated) layer active - output to a new file.
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#5
(06-29-2017, 06:01 PM)rich2005 Wrote:
(06-29-2017, 04:50 PM)The_JinJ Wrote: Good try that...I can't seem to get the filter to work - I have a B&W image as bottom layer and a colored top layer but not merging the two..... any ideas?

I tried wavelet decompose and tidied up the colour residual image with some success.

Not something I use very often, so I usually have to fiddle around with it.

Although it says B & W the image obviously has to be in RGB mode.
then it is set up like this: http://i.imgur.com/rLhrbI8.jpg - all layers - bottom (desaturated) layer active - output to a new file.

Thanks! I had the input layers set incorrectly, obvious mistake Angry
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#6
I did not use G'MIC. In gimp, colors > components > decompose. Choose the red layer. Change Image > mode to RGB.

Then I painted on a new layer, as above, and set it to mode- Color, Opacity- 65%. 

Decompose made a perfect monochrome layer to work with.

I used the original image, above, the image on the right, but you could probably get better highlights with the one on the left.

I could of done a better job of painting, I know.


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#7
Nice!
That's how I ended up doing it, using red channel and ultimately repainting....

Wavelet Decompose was also interesting where you clone colour on the residual layer and smudge to blend.

(07-03-2017, 07:44 PM)grits Wrote: I did not use G'MIC. In gimp, colors > components > decompose. Choose the red layer. Change Image > mode to RGB.

Then I painted on a new layer, as above, and set it to mode- Color, Opacity- 65%. 

Decompose made a perfect monochrome layer to work with.

I used the original image, above, the image on the right, but you could probably get better highlights with the one on the left.

I could of done a better job of painting, I know.
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