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My girlfriend has scanned a few comics images, drawn with pencil. She wants to publish them on the web, but the different grayscale shadows of the paper are still evident in the image.

I would like to make all the light gray colors transferred into while background, using a simple method and open source software.

Any ideas?


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so you basically want rudimentary image editing software. What OS do you use? – zpesk Aug 1 '09 at 21:05
I am platform independent, my girlfriend is an XP user. – Adam Matan Aug 2 '09 at 4:07
up vote 2 down vote accepted

Using ImageMagick you can achieve it like this:

convert source.jpeg -white-threshold 75% target.jpeg

All pixels in the source image with a brightness level of 75% or higher will be set to white in the target image. Just play with the threshold value until you get something that works well. It could be a problem if parts of the drawing comes out brighter than the paper in your scans, but that shouldn't normally be the case.

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That's great. I'll do it and write back about the results. – Adam Matan Aug 2 '09 at 4:08
That worked just fine for me. – Dave Burton Jan 7 '14 at 4:20

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