It will work on both techniques. color to alpha might remove color portions though. fading etc.

You can also just turn the image BLACK and WHITE.

I would try all these methods then pick the one that suits you best. There are several ways of tackling things to end up with the same result.

Very true Molly. Everyone has a different method for the same job ;-}

My attempt: Color to alpha (white) - Colorify or Contrast/Brightness to Black - Duplicate layer - Merge down.

The only method that really demonstrably works for the original question (painting something over transparent background) is the alpha-lock method as indicated by Rich. Other may sometimes work but not for the right reasons.

If you still have it open could you leave the leaves original color and the cup to black? That one actually looks quite good. Also thing is I am going to scale it down a bit so should look fine.

Here is another attempt where I wand selected @ 100 threshold, then color to alpha (white), Contrast/Brightness to black.

that one is a lot better, the last one looked like it had some black fuzz stuck in the white.

It did but that can be easily removed.

O

After adding an alpha channel, I desaturated the image.
Used curves as seen below.


Did a color to alpha on the white.
Alpha selected the black and save the selection as a path.
Stroked the path by 1.


Selected the inside of the stroked path of the image and grew the selection by one and filed it with black.


Final Image

excellent Wallace

Thanks Molly!
I had to alter the path a little, but all in all It seem to work out well.

Hello

May I ask why nobody suggested this typical vector graphic to be designed with Gimps cousin, Inkscape?

It's because the question asked was about changing the color of an existing image using GIMP. Telling someone to use another app is not a very helpful suggestion in a GIMP forum.

Now, if someone were to ask about designing a scalable logo, recommending Inkscape or some other vector graphics app, would be appropriate.

That is very much the path I will have to take. The logo will be used on packaging as well and social media so will definitely be getting scaled quite often (also need one to cover atleast half an a4 page possibly). Gonna check inkscape out but might need to get a freelancer for this job.

There are some very capable people here who use Inkscape. There is another forum called other graphics application with Inkscape under it. Go ask there.

Well, in that case, you might as well send Wallace a check. He's already done most of the work.

Just import this into inkscape.