How OpenCV C++ Interface Manage ROI

Question

Using OpenCV C++ interface how can I write code for setting and resetting ROI For eg: If I need to code like

-> Load image
-> SetImageRoi
-> Do some         


        

Answer 1

Here are the steps you need:

// Load image
cv::Mat image = cv::imread("image_filname");

// SetImageRoi
cv::Rect roi(x, y, width, height);
cv::Mat image_roi = image(roi);
// note: this assignment does not copy data
// image and image_roi now share data

// Do some processing on ROI region
process(image_roi);
// any changes to image_roi will also be in image

// Reset ROI  
//     -- nothing required

// Do some operation on entire image 
operations(image);