How to get a watermark from a photo?

Question

ImageMagick

Let's say there are 1000 pictures and watermark on them, the file with the watermark image is lost.
Watermark is located in the same place, has transparency.
Pictures are the same size.
Knowledgeable people please tell me in which direction to read / dig. (possible in English)
upd: And if there is a picture with and without watermarkom, can something be done?

Answer 1

Using imagemagick, you can get the difference between images with and without a watermark (we get the difference in midtones). Then the resulting image, after applying additional filters, can be traced for conversion into a vector image using programs such as Inkscape or Corel Draw, Adobe AI.