OpenCV: Shift/Align face image relative to reference Image (Image Registration)

Question

I am new to OpenCV2 and working on a project in emotion recognition and would like to align a facial image in relation to a reference facial image. I would like to get the i

Answer 1

cv::Mat does support ROI. (But it does not support COI - channel-of-interest.)

To apply ROI you can use operator() or special constructor:

Mat refimgROI  = faceIMGstore[1](faceROIstore[1]); //reference image ROI
Mat dispimgROI(faceIMGstore[52], faceROIstore[52]); // "displaced" version of reference image ROI

And to find the best position inside a displaced image you can utilize matchTemplate function.

---

Based on your comments I can suggest the following code which will find the best position of reference patch nearby the second (displaced) patch:

Mat ref = faceIMGstore[1](faceROIstore[1]);
Mat disp = faceIMGstore[52](faceROIstore[52]);

disp = disp.adjustROI(5,5,5,5); //allow 5 pixel max adjustment in any direction
if(disp.cols < ref.cols || disp.rows < ref.rows)
    return 0;
Mat map;
cv::matchTemplate( disp, ref, map, CV_TM_SQDIFF_NORMED );

Point  minLoc;
cv::minMaxLoc( map, 0, &minLoc );

Mat adjusted = disp(Rect(minLoc.x, minLoc.y, ref.cols, ref.rows));