Perspective correction of UIImage from Points

Question

I\'m working on a app where I\'ll let the user take a picture e.g of a business card or photograph.

The user will then mark the four corners of the object (which the

Answer 1

If this image were loaded in as a texture, it'd be extremely simple to skew it using OpenGL. You'd literally just draw a full-screen quad and use the yellow correction points as the UV coordinate at each point.