I just used your tool for the first time to try to remove the teal tint of the AOTC blu-ray by comparing it to the DVD and I’m amazed! It worked great on my first try and it looks sooo much better.
But since this is not intended as a perfect color grading for AOTC but just a quick edit for my personal viewing at home, I figured that I don’t want to do the correction scene by scene or even shot by shot. So I took multiple frames, placed them next to each other in one image and tried to compare them. That worked quite well when taking four screenshots (thus creating a 4k image), but when I took 16 the progress bar of the progress bar did not move at all. Is that because I gave up too soon or is there some kind of image size limit?
Yes, 16 images have 25 million pixels for each color channel, which is too large.