Here's my situation: I have grabbed some PNG images from a website that allows browsing a newspaper article at various zoom levels. I imagine that each page has its own full-resolution image file on the server, but the website only serves the image in your current viewbox as you scroll. I have chosen enough images so that they all overlap with each other, and could in theory be used to stitch together the original image file.
I know there is photo editing software out there (like Hugin) which is designed to do this with photos, that don't necessarily overlap perfectly. (Obviously a much harder problem!) But in my case, the pixel values and orientation are exact and don't change. Is there some software that can stitch together these image files for me in a 100% precise manner, as should be possible? I'm happy with either a CLI or GUI for this.
I use macOS by default, but happy to run this on Windows (which I have a VM for). Also have a terminal-only FreeBSD setup on a VM. So, ideally there is a free/OSS solution, but I would perhaps spend max $10.