Remove horizontal and vertical white lines on black background

[mrjulio]

Hello guys,

This is my first post.
I need to remove H and V white lines with black background. The result is a grid generated using -canny 0x1+10%+25%.

The main problem is that the grid is slightly leaning:

I have tried with:

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convert source.jpg -morphology Thinning "1x14: 1,1,1,1,1,1,1,1,1,1,1,1,1,1" -morphology Thinning "14x3: 0,0,0,0,0,0,0,0,0,0,0,0,0,0 1,1,1,1,1,1,1,1,1,1,1,1,1,1 0,0,0,0,0,0,0,0,0,0,0,0,0,0" destination.jpg

... but i get a lot of islands afterwards.

Thank you.

[mrjulio]

I forgot to mention that I'm using ImageMagick-nox11-6.9.0.4,1 on unix.

[snibgo]

What result do you expect? An all-black image?

[mrjulio]

Yes, replace white with black. All lines are 1px thick.

[fmw42]

try this -- change all colors within 20% of white to black

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convert 2131wjq.jpg -fill black -fuzz 20% -opaque white result.jpg

[mrjulio]

try this -- change all colors within 20% of white to black

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convert 2131wjq.jpg -fill black -fuzz 20% -opaque white result.jpg

This will generate a black image. The source is black and white and all I want is to remove lines.
Inside that grid I have text which is also white (result of -canny). I don't want to alter too much of that.

[fmw42]

I do not see any text. Please be more specific about your questions and examples. Please post a real example with your text.

But I do not think you can remove the lines and not the text if they are both the same or closely the same color (white).

If you have two images, one with lines and text and one with only lines, then you can subtract the lines image from the image with both lines and text to remove the lines.

Applying morphology will also change your text.

[mrjulio]

This is an example after running this command on source:

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convert source -sharpen 0x3 -colorspace Gray -canny 0x1+10%+25% -morphology Thinning "1x14: 1,1,1,1,1,1,1,1,1,1,1,1,1,1" -morphology Thinning "14x3: 0,0,0,0,0,0,0,0,0,0,0,0,0,0 1,1,1,1,1,1,1,1,1,1,1,1,1,1 0,0,0,0,0,0,0,0,0,0,0,0,0,0" destination.jpg

If I'm running Thinning with at least 14px long it will not alter the text too much as it will still be readable BUT the image is left with too many ugly islands from straight lines.

[fmw42]

Did you try rotating the image to get the lines more horizontal and vertical, then apply the thinning, then rotate back?

You can also filter out long or short or selected lines using -connected-components. See http://magick.imagemagick.org/script/co ... onents.php

[mrjulio]

I tried rotating the original image to get the lines straight but after -canny i get pretty much the same result.

I will have a look at connected-components.
Thank you.