crop and Save ROI as new image in OpenCV 2.4.2 using cv::Mat

Question

Working on Face Detection and Recognition, and after successfully detecting a face, I just want to crop the face and save it somewhere in the drive to give it for the recognitio

Answer 1

For cropping the region, the ROI(Region of interest) is used. The opencv2 does the job quite easily. You can check the link: http://life2coding.blogspot.com/search/label/cropping%20of%20image

Answer 2

Using cv::Mat objects will make your code substantially simpler. Assuming the detected face lies in a rectangle called faceRect of type cv::Rect, all you have to type to get a cropped version is:

cv::Mat originalImage;
cv::Rect faceRect;
cv::Mat croppedFaceImage;

croppedFaceImage = originalImage(faceRect).clone();

Or alternatively:

originalImage(faceRect).copyTo(croppedImage);

This creates a temporary cv::Matobject (without copying the data) from the rectangle that you provide. Then, the real data is copied to your new object via the clone or copy method.