Image warping - how to proceed I'm studying image warping and I'm unsure how to warp a starting rectangular image into another image where the box corner points have been changed as I want:



(image from http://www.inf.ethz.ch/personal/pomarc/courses/CompPhoto/cpv03.pdf)

As far as I've understood, I need to:

1) Decide the four points (e.g. by using direct mapping on the border cases of the transformation)

2) Create a lattice of integer points on it (how?)

3) Do reverse mapping on those integer points to get the values in the original image

4) ??

I can't say I understood a lot of that, can somebody help me out please?
ImageMagick does that sort of thing, and it's open source.  Look at the source code in magick/distort.c of the current ImageMagick distribution, which you can get from imagemagick.org.  This assumes you have already selected the four control points and passed them in as an option.

The particular distortion method you described is called "binlinear forward" distortion in ImageMagick.  See http://www.imagemagick.org/Usage/distorts/#bilinear_forward