What does Apple Photos for Mac show as a panorama?

Following this thread:

https://discussions.apple.com/thread/252998419 I decided to do a little investigation:

There seems to have been numerous questions over the years asking why a particular photo is not showing in the panoramas view of the library. There seemed to be no definitive answer as to the requirements.

(Note - these tests have been done with MacOS Big Sur, 11.4. I can't be certain this will apply to other versions, but a check is easy.)

I decided to see if I could find out the definition of a panorama. I took an image and resized it to height 1000 and various widths, to see which would go into the panorama view.

Eventually I found that 1000x2750 NOT included, but 1000x2751 was included.

I double checked with a panorama double the size. 2000x5500 not included, 2000x5501 included.

So the key ratio for a panorama seems to be 1:"2.75 plus a pixel".

There is however, a further requirement. An image won't be shown in the panorma view unless it's smallest dimension is bigger than 800 pixels. (801 pixels minimum). So you can't just crop smaller images down to the 1:2.75 ratio if this results in fewer than 801 pixels on the short side.

Videos:

Videos seem never to show in the panorama view even if cropped down to the 1:2.75 ratio. In practice though this makes little difference since the widest standard moving image is the cinema-scope standard of 1:2.55.