Combine layers

[didier]

Hi everybody,

I'm quite totally newbie with Gimp.

As a result, I need some trivial help.

I would like to add a texture to an image.
So, I have my image on a layer and a bump (it is something like that, 3D designers call this) in a second layer.

I've selected Addition for layers mode. It results something not so bad, but, naturally, to much colors of the image saturate to white like expected.

In my mind, bump's range should be [ -128, 127 ] to render as wanted.
Unfortunately, I don't see how to do that.

Perhaps, it's not the right method. Don't know.

Thanks to enlighten me.

Have a nice day and enjoy.

Didier.

[rich2005]

Quote:n my mind, bump's range should be [ -128, 127 ] to render as wanted.
Unfortunately, I don't see how to do that. Perhaps, it's not the right method.

Perhaps not. Is this some method you use in some other graphics application ?

The bump map can be a layer or another open image. Grayscale or desaturated, blurred gives a rounded effect. The docs https://docs.gimp.org/2.10/en/gimp-filter-bump-map.html

For a bump layer, either under the image or visibility turned off.

There is a drop down menu for layer modes in the bump-map dialogue. Filters -> Map -> BumpMap

A demo of that as an animation. https://i.imgur.com/02CEk47.mp4

Otherwise, give an example of an 'expected' result.

[PixLab]

(07-02-2021, 09:54 AM)didier Wrote: I've selected Addition for layers mode. It results something not so bad, but, naturally, to much colors of the image saturate to white like expected.
Didier.

Why addition?
You might not have a full understanding of the blending mode (I mean layer mode, I call it my way )
I would recommend those videos, Ok it's a bit long.... but in the end, when you will chose a blend mode you will know exactly why

https://www.youtube.com/watch?v=i1D9ijh3_-I ( yes it's Photoshop, but it's exactly the same way for GIMP and it's the only guy I found which goes with the "math" and real life usability, also he is enjoyable to listen = not boring)

https://www.youtube.com/watch?v=zGTbOfhyXnA (an older video version of the same guy, worth a watch as well, with more real life examples)

An important video about "color to alpha" to blend whatever you want to blend with another layer
https://youtu.be/YQCE2_tMcN4?t=275 (this one is the "Blend if" of GIMP (menu Colors/Color to alpha), a tool which is way underrated and does wonders when you use the sliders, watch it up to the end or you will miss many things (I've timed the video to pass the Photoshop part and go straight to the GIMP part))

[didier]

Nice.
Thank you for your instructive answers.
My mind is clear now.

Thank you again