Question

I am new to OpenCV and I am learning to do some image processing. As a part of my project, I have a problem of warping an image patch in form of an ellipse into a destination ellipse. As far as I understand, I would need to calculate the affine transform between the two patches, and then warp this transformation into the destination patch. Browsing the internet for help, I didn’t find a way to calculate affine transforms between two elliptical patches. Am I on the right track? I would be grateful if you could give me some suggestions how to proceed or where to look for more information.

Answer 1

The fact that your elements are ellipses is not relevant to the calculating of the transform. Transforms work equally well on arbitrary shapes. Say you have affine transforms [A] and [B] with respect to some origin O, you want the transform between [A] and [B]. There are several ways of thinking about doing this, the simplest one, is to get the transform from [A] to O, then from O to [B] and combine them. [A] to O is simply the inverse of [A] and O to [B] is just [B] so

final_transform = [B]*inverse([A]);

here is a similar question, solving with vector representations is equally valid.

To do the actual warping you can use cv::warpAffine