How to change all pixels in Gimp that are not one of two colors to white?


I was trying to submit an app to the Windows Phone app store. Here all pixels need to be white (#FFFFFF) or transparant (#FF####).

I had a black logo on a white background. To make the background transparant and the foreground white I used Gimp. First I made the background transparant using the magic wand and changing color to alpha. Then I inverted the remaining colors. Unfortunately the images did not get accepted in the Windows Phone app store because not all pixels were white or transparant.

How can non-white or transparant pixels in Gimp be converted to white?

10/21/2015 10:13:00 PM

Accepted Answer

Are you sure you need the GIF format? PNG would allow smooth edges with transparency.

To edit the output colors you should first set your color mode to Indexed (Image > Mode > Indexed). For the conversion select Use black and white (1-bit) palette

Then you can edit the color table (Window > Dockable Dialogues > Colormap). Just doubleclick the black color and set it to white.

Edit: For a PNG you can use Colorize (Colors > Colorize) where you can set Lightness to +100 to make everything white. This will keep transparency intact.

10/27/2015 1:59:00 PM

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