I do quite a lot of bump mapping, but I don't quite understand what you are trying to bump map. That image you posted looks like a composite. Ideally to bump map you need a black and white image. Do you have an xcf or psd of the file with separate layers?
Also, bump mapping is a destructive process. What is a better idea is to fill a layer with 50% gray, hex code #808080, then run the bump map on that gray layer. If you choose a layer mode like overlay or soft light and put the layer on top, it has a bump effect and is non destructive:
A 50% gray bump mapped to the image.
That layer in 'Overlay' over the original image.
Again, this is not ideal. You really need a black and white height map do do this correctly
Gimp 2.10 is a little different from 2.8.
When you select map->bump map, then you have to select the image and the layer to bump map.
The bump map results are on whatever layer is active. As I said before, I recommend using a 50% gray layer in 'overlay' or 'soft light'
Also, bump mapping is a destructive process. What is a better idea is to fill a layer with 50% gray, hex code #808080, then run the bump map on that gray layer. If you choose a layer mode like overlay or soft light and put the layer on top, it has a bump effect and is non destructive:
A 50% gray bump mapped to the image.
That layer in 'Overlay' over the original image.
Again, this is not ideal. You really need a black and white height map do do this correctly
Gimp 2.10 is a little different from 2.8.
When you select map->bump map, then you have to select the image and the layer to bump map.
The bump map results are on whatever layer is active. As I said before, I recommend using a 50% gray layer in 'overlay' or 'soft light'