Cleaning up a partition

[tonux]

Hello,
I would like to remove the greyish background from this scanned document. The difficulty is that this background is made up of pixels in different shades of grey, some of which are found in the elements to be kept. In this case, the colour selection tool does not give good results.
This is why I am looking for ideas on this forum. So thanks for any suggestions.

GT

[rich2005]

For that particular sample:  The greyish background is actually dithering, the scan might have been indexed at one time or it might have been the scanner software.

You can get some improvement by
1) Apply Filters -> Generic -> Dilate (grows light areas and shrinks the dithering to nothing)
2) Apply Filters -> Generic -> Erode (grows darker areas to try and get most of the original back)
3) Play with the color curves tool to get a little darker.

A 30 second demo of that:  https://i.imgur.com/9U8qJoy.mp4

   

[tonux]

(09-13-2022, 05:31 PM)rich2005 Wrote: For that particular sample:  The greyish background is actually dithering, the scan might have been indexed at one time or it might have been the scanner software.

You can get some improvement by
1) Apply Filters -> Generic -> Dilate (grows light areas and shrinks the dithering to nothing)
2) Apply Filters -> Generic -> Erode (grows darker areas to try and get most of the original back)
3) Play with the color curves tool to get a little darker.

A 30 second demo of that:  https://i.imgur.com/9U8qJoy.mp4

Wonderful. It works fine, the result is beyond my expectations.
Thank you very much rich2005

GT

[Ofnuts]

Another method:

* Filter  > Blur > Median blur with a 1px radius (left)
* Possibly, and additional contrast increase with the Brightness/Contrast tool (right)

   

[Krikor]

Another option to check:

G'MIC - Repair - Repair Scanned Document, with default options.

[denzjos]

Another option : clean up with 'Filters / Artistic / Photocopy'
   
Duplicate the cleaned layer and set the layer mode 'Multiply'