How to change line color ...?

[Fifinella]

Hi All,

Need help on how to change this black lines to white lines. I am stumped on how to do this, probably a simple thing to do but I cannot figure it out. Fill attached 

Gimp 3.2.4

End image to be a white airplane outline on a blue background.

Thanks for any help.
Cheers KAP

[rich2005]

(07-02-2026, 04:19 PM)Fifinella Wrote: Need help on how to change this black lines to white lines. I am stumped on how to do this, probably a simple thing to do but I cannot figure it out. Fill attached 
End image to be a white airplane outline on a blue background.

Your problem is your color-to-alpha still has a blue tinge.

     

(1) Undo the Color to Alpha (fx) (or go back to the original)
(2) That gets a light background color. Apply Color-to-Alpha again. Carefully color pick the background and set the transparency threshold to about 0.5 Turn the Merge Filter toggle ON.

   

(3) That gets black lines on a transparent background. In the layer dock click next to the visibility (eye) icon and lock the alpha channel. Do it correctly and you get an icon under the lock column.
(4) Now bucket fill with White (BG in my screenshot) and Fill whole selection ON
(5) Undo the alpha lock (same procedure as 3) Turn the bottom layer visibility on.

[sallyanne]

Wouldn't 'invert colour' turn the black lines to white? Doesnt affect the transparency either.

[rich2005]

(07-03-2026, 01:22 PM)sallyanne Wrote: Wouldn't 'invert colour' turn the black lines to white? Doesnt affect the transparency either.

It does but you have to make sure that transparency is 100 %

An alpha lock and fill is more  "universal" ( you still have to make sure transparency is 100%)