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Posts Tagged ‘gimp’

Gimp ColorToAlpha as Standalone EXE

I love Gimp as much as I love Photoshop, but in last one I miss one of the simplest and coolest plugins out there: ColorToAlpha. I know you can mimic this plugin in Photoshop and also with some Imagemagick scripts but at the end output is not as nice as Gimp plugin.

What it does is to remove target background color by adding transparency and modifying original colors in a way that when you combine with base color you have exact original image.


For me this is a basic function I use in each presentation, when you have to overlap images or want to perfectly merge a logo that comes with white background. Initially I thought I could create a photoshop plugin just taking a look at Gimp code… It was not so easy.

So finally I did a quick C# implementation of original Gimp code and created a single exe that do same thing as Gimp plugin does. The target was to be able to do this without any software and in mass mode trough a loop in a DOS script.

Not sure if it’s usefull for you, but just in case here you have it!
Download colortoalpha.zip (4kb)

Unzip colortoalpha.exe and use trough command line.

Usage: colortoalpha FileIn [BackgroundColor] [Dir or FileOut]
BackgroundColor = white, black, red, green, blue or any #hex color (default=white)
Output file will be “.png”
Warning! If not FileOut then FileIn will be overwrite if share .png extension without asking!!

colortoalpha test.jpg
colortoalpha test.jpg #b400ff testout.png
colortoalpha test.jpg white c:\tmp\
colortoalpha c:\temp\test.png red c:\tmp\test3.png

Don’t really know limitation in image sizes or formats neither tested it.

Use at your own risk!