removing fold shadow / highlight from a scan

[Krikor]

(01-05-2021, 04:03 AM)The ancient one Wrote: I hate to admit it but this has got me beat.
 
My layers dialog is exactly the same as in the on line manual chapt 16 Figure 16.104. The Contents of the “Layer” local pop-menu
 
and in my windows dialog the same as in Figure 16.259. Contents of the “Windows” Menu
 
I have right clicked the picture and thumbnail and clicked through all the menus that I can find an I cannot find the menu you posted

This is a whole new ballgame for this ancient one and I do not want it to beat me.

You can easily find this in through the menus:
Windows - Dockable Dialogs - Layers. Or by the shortcut Ctrl + L.

In the layer dialog window, check the Mode option (the default is Normal).
Through a pop-up menu you can find the Grain Extract option.

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(01-05-2021, 08:22 AM)The ancient one Wrote:

(01-03-2021, 09:01 AM)Ofnuts Wrote: Actually I use a better technique now:

• Filters>Enhance>Wavelet decompose
  
• On the Residual channel: "Filter>Blur>Pixelize" and pixelize to its size to average it.
  

You can also at the same time duplicate the top layers to increase sharpness/contrast of text.

I guess I am just too old to grasp some essential as the two dot points produced nothing but a fuzzy mess.  Presumably I am missing some blindingly obvious next step.

I did not do the third step as I wanted to see how it looked before and after

I confess that I also did not understand very well.
My interpretation was as follows:
Apply the Wavelet Decompose filter.
Then in the Residual layer (highlighted in yellow in the image below) apply Filter> Blur> Pixelize - (Highlighted in yellow).
   
I changed the mode of this layer (Residual) to Divide. (highlighted in red)

NOTE: It is in that same menu (highlighted in red) that the Grain Extract option is found.

[Ofnuts]

(01-05-2021, 03:55 PM)Krikor Wrote:

(01-05-2021, 04:03 AM)The ancient one Wrote: I hate to admit it but this has got me beat.
 
My layers dialog is exactly the same as in the on line manual chapt 16 Figure 16.104. The Contents of the “Layer” local pop-menu
 
and in my windows dialog the same as in Figure 16.259. Contents of the “Windows” Menu
 
I have right clicked the picture and thumbnail and clicked through all the menus that I can find an I cannot find the menu you posted

This is a whole new ballgame for this ancient one and I do not want it to beat me.

You can easily find this in through the menus:
Windows - Dockable Dialogs - Layers. Or by the shortcut Ctrl + L.

In the layer dialog window, check the Mode option (the default is Normal).
Through a pop-up menu you can find the Grain Extract option.

---

(01-05-2021, 08:22 AM)The ancient one Wrote:

(01-03-2021, 09:01 AM)Ofnuts Wrote: Actually I use a better technique now:

• Filters>Enhance>Wavelet decompose
  
• On the Residual channel: "Filter>Blur>Pixelize" and pixelize to its size to average it.
  

You can also at the same time duplicate the top layers to increase sharpness/contrast of text.

I guess I am just too old to grasp some essential as the two dot points produced nothing but a fuzzy mess.  Presumably I am missing some blindingly obvious next step.

I did not do the third step as I wanted to see how it looked before and after

I confess that I also did not understand very well.
My interpretation was as follows:
Apply the Wavelet Decompose filter.
Then in the Residual layer (highlighted in yellow in the image below) apply Filter> Blur> Pixelize - (Highlighted in yellow).

I changed the mode of this layer (Residual) to Divide. (highlighted in red)

NOTE: It is in that same menu (highlighted in red) that the Grain Extract option is found.

You don't need to change the layer mode (and in fact, changing the layer mode of the bottom layer doesn't change anything).

The explanation for the whole process:

• Wavelet decompose the image in layers, where each layer corresponds to details at a given spatial frequency, range, a bit like bargraphs on sound equalizers show the intensity of sound in a govern frequency range.
  
• The top layers are the high frequency components (ie, the small details).
  
• The "Residual" layer is the very low frequency component, and is more or less the lighting variation on the background.
  
• Filter>Blur>Pixelize replaces it with a uniform version of itself (this is a way to compute the average volor of the layer). so there are no more lighting variations, and the image background is uniform.
  
• Some other large size artifacts (folds) can be in other lower layers, that can be averaged out in the same way.
  

[The ancient one]

A big thanks to both of you.
Too late for me to try anything today and in no mental condition to try all day.
Hoping for tomorrow