I am trying to use a linear transformation to straighten out the camera angle on this image:
In other words, I want to transform the image into a head-on view of the whiteboard.
I applied an affine transformation to that image, identifying the top left, top right, and bottom left corners, thinking that it would turn the image into a 1080x720 rectangle. However, here's what I ended up with:
As you can see, it is NOT a rectangle, but some sort of misshapen quadrilateral. It's close, but not exactly a head-on view of the whiteboard!
What exactly happened here? I really thought an affine transformation would work.