Re: [Gimp-user] How to clean the photo of the paper with drawing?

2010-10-05 Thread Milan Vancura
 Duplicate the layer and remove all the dark lines/text with the 
 Dilate filter, repeat until they are all gone.
 
 Gaussian Blur this duplicated layer with a large radius.
 
 Effectively you want to subtract this duplicated layer from the 
 original, do this by setting the layer Mode to Grain Extract, then 
 Flatten.

Thank you, Bruno.

I tried this and it works quite well.

I also found another way meanwhile:
Decompose the image by Wavelet function (part of my gimp 2.6 or as a plugin
http://registry.gimp.org/node/11742 ) and clear the first layer - the one
with details of larger scale - with the neutral color (128,128,128).
Or fill that layer with white and set the brightness and contrast of the image
after it is flattened again.

I'm surprised there is no tutorial about this - probably a good chance to write
new one - when I get really good results.

Milan
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Re: [Gimp-user] How to clean the photo of the paper with drawing?

2010-10-01 Thread Bruno Postle
On Thu 30-Sep-2010 at 18:59 +0200, Milan Vancura wrote:

 I tried to find tips how to clean a photo of the drawing but 
 with no success.  I have a photo of a paper with drawing (usually 
 a combination of heavy lines by marker and thin pencil ones) and 
 want to improve the image for printing. So I want to get white 
 background of 100% of the image (no shadows) and still have all 
 details of drawing kept. Even if they are sometimes lighter than 
 shadows in different part of the image. For example a dark shadow 
 in the cormer and light pencil line in the middle.

This is what I do:

Duplicate the layer and remove all the dark lines/text with the 
Dilate filter, repeat until they are all gone.

Gaussian Blur this duplicated layer with a large radius.

Effectively you want to subtract this duplicated layer from the 
original, do this by setting the layer Mode to Grain Extract, then 
Flatten.

The result will have an even grey background, adjust the Levels to 
make it white again.

This works very well, I use it for cleaning up photos of sketches, 
whiteboards etc...  There is an alternative method using a 
Convolution Matrix, but it doesn't get such good results for me.

-- 
Bruno
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[Gimp-user] How to clean the photo of the paper with drawing?

2010-09-30 Thread Milan Vancura
Hello all,

I tried to find tips how to clean a photo of the drawing but with no success.
I have a photo of a paper with drawing (usually a combination of heavy lines
by marker and thin pencil ones) and want to improve the image for printing. So
I want to get white background of 100% of the image (no shadows) and still
have all details of drawing kept. Even if they are sometimes lighter than
shadows in different part of the image. For example a dark shadow in the cormer
and light pencil line in the middle.

I tried to play with brightness  contrast. This is not good enough as many
details are lost. Typically the pencil drawing. Levels are unusable for the
same reason.

I tried to look for edge-detection filters but they all do something else than
I need: they left a thin line around the edge, not the original line itself.

Probably a FFT (Fast Fourier Transformation) filter would help but I did not
find any.

Any ideas, please?

Milan
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