Comment by lowdest

If you see the blog about the process linked in another comment, you see that AI was used to stitch 2-page images together that could not be flattened to be scanned together, and to remove the seam where the book binding pinched away part of the image.

Comparing the before and after, they appear to be quite accurate to the originals; almost all of the "restoration" appears to be in color correction for faded ink and paper.