The original components of the image on the left are vector graphics files, so the lines in the original images are precise and the colours (i.e. shades of gray, in this case) are also precisely known.
But in order to upload the images, I needed them to be jpegs, which results in a certain loss of precision in the lines, although not so much in the colours.
Having produced jpegs, I then printed them (in a store, using a self-service kiosk) to produce 6in by 4in prints.
I then placed them adjacent to each other on a scanner and scanned them in to produce the image at the left.
Remarkably, in my opinion, the deterioration after the initial deterioration experienced going from vectors to raster, is rather minimal.
You can see the initial jpegs in earlier posts here and here, if you want to check the deterioration. You will need to blow up corresponding sections of the image to compare them effectively.
I should probably go through the sequence one more time, but that means another drive to the store, so I'm not going to do it this evening. Watch this space.