Change one color of a 2 color picture

[kbrick66]

I took a picture of an antique radio dial and I want to clean it up to print a new face. I've got it cleaned up but I want to change the color of the text on the black background. Is there a way to change the color of the text only to another color in one action? I'm new to GIMP and the controls are a bit overwhelming. Thanks for any help.

Ken

[Ofnuts]

Plenty of ways. If your dial has black markings on a white background(*), you can use a paint tool in "Lighten only" mode. Since it paints only if it makes the pixels lighter, and that any color is lighter than black but darker than white, it only applies color to the markings.

For other suggestions, please attach your image, each image has its own problems.


(*) If necessary you can use "Colors>Brightness contrast" to make the dark parts darker and the light parts lighter.

[kbrick66]

Thanks for the reply. My situation is a black background with nearly white lettering. I want to make the lettering more of an amber color.How about doing that?
Ken

[rich2005]

All sorts of ways to change the colour of lettering,

However, black background is potentially easy.

Just two colours, black / (off) white. 
(1) Make sure the image is in RGB mode Image -> Mode -> RGB
(2) Use Colors -> Hue-Chroma filter. Adjust the sliders to get what you want, and then OK it.

example: 

   

[kbrick66]

(03-12-2020, 05:54 PM)rich2005 Wrote: All sorts of ways to change the colour of lettering,

However, black background is potentially easy.

Just two colours, black / (off) white. 
(1) Make sure the image is in RGB mode Image -> Mode -> RGB
(2) Use Colors -> Hue-Chroma filter. Adjust the sliders to get what you want, and then OK it.

example: 

I tried your suggestion, thank you. It didn't work very well for me. As I increased the chroma or other adjustments, the background black would also change if I went too far. Any other suggestions? I need the black to be as black as can be.

---

Not sure if I replied correctly so I'm sending it again. Sorry if this comes through twice.
I tried your suggestion, thank you. It didn't work very well for me. As I increased the chroma or other adjustments, the background black would also change if I went too far. Any other suggestions? I need the black to be as black as can be.
Ken

[Krikor]

(03-12-2020, 08:10 AM)Ofnuts Wrote: Plenty of ways. If your dial has black markings on a white background(*), you can use a paint tool in "Lighten only" mode. Since it paints only if it makes the pixels lighter, and that any color is lighter than black but darker than white, it only applies color to the markings
(*) If necessary you can use "Colors>Brightness contrast" to make the dark parts darker and the light parts lighter.

Following the tip above Ofnuts, and considering that the background is black and the markers are white, I just changed it to Dark Only in brush mode.
       
Markers 2, 9, 10 and 11 colored in color c9b359

[Ofnuts]

If you start with white marks on black, just set you paint tool to "Multiply" mode and bucket-fill with the required color (color*white=color and color*black=black).