Feature Request: Pan and zoom on slideshows.

[TheDoktar]

The Rather pretentiously-named Ken Burns Transition aims to make slide shows more interesting by offering a slow zoom in or out while at the same time panning the shot. At the moment its a feature not offered by Feh, but many screensavers on TVs do this by default, either a little or significantly. When chosen for the specific image, the effect is really stunning making the image come alive.

Could Feh offer such a thing, and if it could what exactly would or should be offered?

One possibility is the fully configured possibility where each image has its own parameters, where to start the image center, where to start the zoom at, and how these two parameters should change over time. (both direction and speed, both assumed to be constant.)
There could need to be support for setting these up graphically. This gets quite complicted then.

Another possibility is a more minamalist approach with a series of options set up that would be randomly chosen at run time for each image if there was more than one, or always or sometimes applied. From an artistic viewpoint, even a very minimal effect can be significant (zoom that does not vary much from full screen and pan that is always close to screen center. )
I think that this could be really good and would require minimal changes. Probably we'd need a new option (are there any letters of the alphabet left???? ) and at its simplest could be something like --pannzoom 90%->100%,x-10%,y-5%->x0,y0 In words this would be Start zoom at zoomed in to show 90% of linear screen, starting with center offset by 10% in x direction and 5% in y direction chaning to 0,0 over the display duration of the slide. So still not simple, but perhaps simple enough.

Thoughts?