OpenCV 3 Computer Vision Application Programming Cookbook - Third Edition

Defining regions of interest

Sometimes, a processing function needs to be applied only to a portion of an image. OpenCV incorporates an elegant and simple mechanism to define a subregion in an image and manipulate it as a regular image. This recipe will teach you how to define a region of interest inside an image.

Getting ready

Suppose we want to copy a small image onto a larger one. For example, let's say we want to insert the following logo into our test image:

To do this, a Region Of Interest (ROI) can be defined over which the copy operation can be applied. As we will see, the position of the ROI will determine where the logo will be inserted ...