Simulating Camera - Image Geometry (Sensor+Lens - FOV)

Hi everybody. I need to simulate a virtual camera. In this stage, I need to simulate with real life images, which I took with a camera with two different focal lenght lenses, IMAGE A (with a 28mm) and IMAGE B (with a 50mm lens).

My question: is there a toolbox, or an app, with instruments with which I might be able to "distort" image A and obtain a similar image to image B, thus simulating in-Matlab the changing of focal lenght?

I attach the two images for clarity [the superimposed info text won't be present in the simulation]. Thanks in advance, any suggestion will be helpful.

IMAGE A:

IMAGE B:

Answer 1

[Yun Peng]

http://www.petercorke.com/MVTB/r3/html/CentralCamera.html

This might be useful to you. Google Peter Corke. He has a set of matlab models to simulate a real-life camera.