How can I transform a fish_eye image to a flat rectangular image?

I have been trying to do a "inverse" fisheye lens effect, which means to transform a "fisheye" image to rectangular/square image using matlab for few weeks, but still without a good solution.

Basically it is just an 开发者_如何学Cinverse of How can I implement a fisheye lens effect (barrel transformation) in MATLAB?

Could anyone tell me how to do this please?

You should look at Jean-Yves Bouguet's Camera Calibration Toolkit. If you have the camera you can follow his steps to calibrate the camera yourself. Otherwise you will have to know something about the geometry of the lens.