(08-05-2025, 11:04 PM)saint_m Wrote: ......hmmm - i think that i can use th Color to Alpha filter in GIMP
this "color To alpha " can be found in the "Color"-Menu.
Use Color-to-Alpha (C2A) to remove a single color background when possible. It keeps semi-transparency including the edge anti-aliasing. For your image, some color is also removed. Fixed to a certain amount using C2A opacity slider but this can also removes anti-aliasing. Up to the user to decide what is acceptable.
Quote:....i have addes another example of and image here...
this should converts a selected color in my image to transparency. This filter - note it is located under the "Colors" menu and well i think it might be useful for removing a specific color: In my case i want to remove the green color of the dots - i want to make them all black.
well i think this should be possible, (( while preserving anti-aliasing and blending effects.))
An alternative way because the dots in the image are small and lose that important anti-aliasing. Using a trick to remove the color background and restore ant-aliasing.
about 2 minutes https://i.imgur.com/WJMJEh9.mp4
What it shows:
Check the alpha-channel Layer -> Transparency - OK it has one
The trick: Scale the layer up 200% Image -> Scale image Use Interpolation = NoHalo
Color Select the background and Edit -> Cut to delete it
Select -> Invert and click on a dot to select.
Fill the selection with color (black)
Select -> None
The trick: Scale the image down to 50% back to original size, the interpolation (NoHalo) adds anti-aliasing.
Save this image and add to your background File -> Open as Layers. Merge down as required.