How do I transform an image to match another in terms of scale/rotation/aspect ratio?
Like in this question, I want transform/rotate an image to match another one (by scale/rotation). Specifically, I want to edit a remake of an old image by cropping/transforming/rotating to match the original)
The tool is not important for me but I'm working on a Linux machine, so Gimp seems to be the first choice. I tried the two-layer approach from the answer in the linked question but this doesn't work because while aligning the transparent layer it becomes opaque.
Is there a way (with whatever tool) to select corresponding points in both images and use points to transform one of the images to match?
How would you do this?
If the two images are only similar, but not taken from exactly the same place, you might want to just stick with a similar cropping, as any control-point based transform might distort your image in strange ways. If you need to adjust rotation relative to the original image, you can load it as a background image in gimp (up or downscaling to your new image as appropriate) for use as a guide.
In order to see the layer while using the rotate or other transform tools, hide the upper layer in the layers stack and adjust the opacity of the preview in the Tool Options tab of the toolbox. Note that some versions of gimp on older hardware might be somewhat unresponsive when trying to rotate large images with the preview enabled, unfortunately.