Using ImageMagick to remove all color except black in an image?

Question

The situation is : I have many images of documents from scanning. I want to keep the document\'s main content - which is printed in color black (a small range of colors arou

Answer 1

I stumbled upon this question while looking for an answer to this question. I found a couple imagemagick forum posts that helped. Here is what I came up with:

convert input.gif -matte \( +clone -fuzz 1 -transparent black \) -compose DstOut -composite ~/Desktop/output.png

Forum post: ImageMagick: Removing all but one color

Answer 2

To match all colors except black you can use +opaque "#000000".

In order to include a little range around #000000 you can try different percentages with the fuzz operator:

convert input.png -fill white -fuzz 10% +opaque "#000000" result.png

Tested with ImageMagick 6.6.0-1 on Windows

Answer 3

You should try the level command:

convert test.png -level 25%,75% test_level.png