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 image translation working before moving to rotation. Current idea is to run a search within a limited range on both x and y coordinates and use the sum of squared differences as error metric to select the optimal x/y parameters to align the image. I'm using the OpenCV face_cascade function to detect the face images, all images are resized to a fixed (128x128). Question: Which parameters of the Mat image do I need to modify to shift the image in a positive/negative direction on both x and y axis? I believe setImageROI is no longer supported by Mat datatypes? I have the ROIs for both faces available however I am unsure how to use them.

void alignImage(vector<Rect> faceROIstore, vector<Mat> faceIMGstore)
{
  Mat refimg = faceIMGstore[1]; //reference image
  Mat dispimg = faceIMGstore[52]; // "displaced" version of reference image
  //Rect refROI = faceROIstore[1]; //Bounding box for face in reference image
  //Rect dispROI = faceROIstore[52]; //Bounding box for face in displaced image
  Mat aligned;

  matchTemplate(dispimg, refimg, aligned, CV_TM_SQDIFF_NORMED);
  imshow("Aligned image", aligned);
}

The idea for this approach is based on Image Alignment Tutorial by Richard Szeliski Working on Windows with OpenCV 2.4. Any suggestions are much appreciated.