Thread Rating:
  • 0 Vote(s) - 0 Average
  • 1
  • 2
  • 3
  • 4
  • 5
Reconstructing an image from overlapping parts
Note: this method applies only to bigger images cut out properly (for instance, multiple screenshots of something too big to fit on a screen), not to picture extracts done with a handheld camera/smartphone that are in the realm of panorama software such as Hugin). This method can also give decent results with partial scans, but this assumes that there is very little distortion in the scanner, which isn't always a given.
  • You temporarily set the layer at the top to Difference mode. This will show you outlines in both pics where they overlap. Yes, the top layer doesn't show in the areas where there is nothing below it.
  • You move the top layer and and when the position is pixel-perfect the overlap goes completely black. In the last stages you can move the layer pixel-by-pixel using the cursor keys (or you can zoom in to some part of the image with many small details)
  • You set the top layer back to Normal mode to restore the full image.
  • Rinse and repeat for every layer.
One thing led to another...

In order to reproduce the steps of this tutorial but without having an image at hand (for instance, multiple screenshots of something too big to fit on a screen, etc), I decided to intentionally misalign an image.

In this game I ended up discovering how to create interesting aspects of sketches.

Duplicate the original layer;
Rotate the new layer by 0.60 (with rotate tool); OR (I found out later, move with the Move tool about 6 spaces to one side)
Change this layer's mode to Difference;
Making new of the visible;
On this new layer (Visible):
a- Invert the color - Colors - Invert;
b- Colors - Levels - Low Input - 230 (I used 230, but this value must be adjusted depending on the image used);
c- Colors - Desaturate - Desaturate.

I discovered that, unlike the Move tool, with the rotate tool, it is not possible to preview the correctness of the layers.

Ofnuts, thanks for the tutorial and for indirectly helping me figure out how to create interesting sketch looks.
Samj PortableGimp 2.10.28 - Win-10 /64.
I really appreciate this tutorial Offnuts. I expect it to be quite useful!

Oddly, I never before have been able to move layers using cursor keys. Guess I always tripped up under the expectation that having the target layer "active" in the layers dialog ...should have been sufficient to select it. And when that didn't work, I just concluded the solution was over my head.... But, thanks to your challenge, I worked it out (after all these years"   Wink

[Image: Difference-Test.webp]


Forum Jump: