Of the 3 pictures you posted, this is the only one with any depth to it at all, but it's inverted. Switch left and right, and it's pretty good. I suggest you make new post with the correction.
The other two are completely devoid of a 3D effect.
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Oh that's interesting, I definitely get a depth of field with the other two, but you're right that this one is much more pronounced. In any case, I didn't make them. They were produced in the early 1800s by Ben Franklin, and it wouldn't feel right to edit them (not that I have the know-how).
Then perhaps you should post it to the !parallelview@sh.itjust.works community instead.
The other two have no discernable 3D effect for me, when comparing elements inside the photo (e.g. one rock should appear closer to me than another rock). Maybe if they were blown up to a bigger size, some 3D effect might start to appear, but that's not possible to see with the parallel method. Maybe with some viewing device that these were specifically made for.
The editing I suggested is dead easy: just switch the position of the left image and the right image. You can learn to do it in any photo editing software - or in Paint for that matter - in a matter of minutes.
