I think the first thing to remember is you can't automatically make any modified image more detailed than its parent. So if the image you have is seen at an angle, ie. it's forshortened, you can stretch it to the flat full on width/height, but the detail will be the same. I guess you could then hand work it in a paint program if necessary to create better detail. This is the sort of thing 3D renderers do very well, eg. LightWave, Imagine, Tornado, Cinema4D, etc. They can project flat images onto a flat 'screen' then warp the screen along with the image. This effect could be done in reverse by projecting the forshortened image onto a screen orientated like the surface in the original photo. Moving the viewpoint will give you a more or less full face image. It will still retain any curvature if the screen is curved, but even that could be morphed into a flat surface and the image would follow suit.
Sounds like a lot of work after a lot of learning.
JaX
