Shadow of the Cat (1961 Hammer widescreen) divx.avi

Thriller from Hammer Films of England.
From TV, processed to divx+mp3.
Image size is 568x360, which is some kind of odd aspect ratio (1.58) I don't understand. Shapes are correct.

I theorize that the TV was broadcasting it widescreen 1.66 and this was just some natural cropping in the transmission. To rip something like this correctly first you start with the correct full letterboxed frame of 4:3. Then maintaining the shape you crop the image.
It shows what a crazy business ripping can be.