Help changing the colors of a height map to match another

[saramello]

Essentially I'm working on a map project, and part of it is a height map overlay. I want to change to a new projection but the height map has a different color scheme (off-color file) that isn't the pure white and black as the previous height map for the other projection. When I try to layer the new one using the multiply layer tool, the resulting image is significantly darker, as opposed to the previous projection overlay, which would not darken the image at all except for adding definition to mountains. 

 

So, how can I change the color scheme of one png to match the other? If it's possible?

[MJW]

Seems to me you probably need to describe more precisely the transformation you want to make. Doesn't seem to me it's just changing one color scheme match another, whatever exactly that means.

 

UPDATE: To perhaps be clearer, it's relatively easy to guess how a black and white image represents height, but without knowing how the other format represents height, it's difficult to know how to transform one to the other.

 

Also, I'm not sure what those unlabeled images are supposed to show.

[Tactilis]

1 hour ago, MJW said:

Also, I'm not sure what those unlabeled images are supposed to show.

It's a map of Spain & Portugal:

[MJW]

2 hours ago, Tactilis said:

It's a map of Spain & Portugal:

 

Sure, but what are the images supposed to show about the relationship between the height mapping methods?

 

UPDATE: If, by chance, the first is the black and white version, and the second is the other version, the problem appears to go beyond remapping the colors. In the mountainous region of the second image, there are dark specks of color scattered upon a white background. That would seem to make no sense for a true height map, which should be relatively continuous. Maybe the non-white dots represent points where the height has been sampled; but in any case, I don't believe it's just a matter of remapping colors.

[Ego Eram Reputo]

On 4/26/2024 at 6:11 AM, saramello said:

When I try to layer the new one using the multiply layer tool, the resulting image is significantly darker, as opposed to the previous projection overlay, which would not darken the image at all except for adding definition to mountains. 

 

For this to work, I think Multiply is the wrong choice. Try Difference  REF: https://www.getpaint.net/doc/latest/BlendModes.html#18

 

Quote

Difference: The counterpart to Additive blending. The layer pixel's intensity is subtracted from the composition pixel's intensity resulting in darker colors.  Subtraction could produce a negative intensity which is unable to be displayed, so an absolute value is returned.  Thus, both "white minus black" and "black minus white" will both produce white.

 

With Difference, I got some mountain shadowing to show through at the cost of a darkening of the source image.

 

[MJW]

2 hours ago, Ego Eram Reputo said:

With Difference, I got some mountain shadowing to show through at the cost of a darkening of the source image.

 

I don't think that's the image saramello (the OP) is concerned with. I think s/he wants to transform one of the small images in the head post to be like the other (or something like that). Tactilis just introduced that map image to show what the original two height map images represented. I doubt the second small image is a normal height map, so I'm not sure it can be done without a lot of effort.

 

UPDATE: Perhaps I'm just confused about what you're doing or demonstrating, Ego Eram Reputo. If you're using a blown-up version of the second small image to modify the map in the way the OP wants to do, I'd say that's very sensible, though it would seem to depend on the blurriness resulting from greatly magnifying the second height-map image. Actually, this whole thread leaves me rather confused.

[Ego Eram Reputo]

22 hours ago, MJW said:

Actually, this whole thread leaves me rather confused.

 

I took it that the grayscale image in the first post was to provide topological shadowing when blended over a flat map of the same scale.

[Tactilis]

4 hours ago, Ego Eram Reputo said:

I took it that the grayscale image in the first post was to provide topological shadowing when blended over a flat map of the same scale.

Yes, very likely.

 

If you take this coloured elevation map, convert it to greyscale and fiddle around with the thresholds, you can get close to the first image @saramello posted.

 

 

@saramello's second image is a contrast-stretched, very low-resolution (i.e blocky), colour-inverted equivalent: