Question

I’m working on a project using OpenCV on template matching, and I want to limit the search region on an image. Image is captured continuously from a camera.

Is there any way to Zero / mask out image outside ROI defined, so that template matching process can be specific on remaining region, faster and accurate?

Answer 1

Take a look at the cvSetImageROI function.

void cvSetImageROI(IplImage* image,
CvRect rect)

Sets an image Region Of Interest (ROI) for a given rectangle.
Parameters:

• image – A pointer to the image header
• rect – The ROI rectangle

If the original image ROI was NULL and
the rect is not the whole image, the
ROI structure is allocated.

Most OpenCV functions support the use
of ROI and treat the image rectangle
as a separate image. For example, all
of the pixel coordinates are counted
from the top-left (or bottom-left)
corner of the ROI, not the original
image.