Sometimes it might be a good thing to let OpenCV know where to search for something. In this recipe, we'll take a look at how we can set the Region of Interest (ROI). We'll set the ROI to the right part of the screen and use the face detection algorithm from the previous recipe. OpenCV will only be able to detect faces in this region.
The code for this sketch is basically the same as the code from the previous recipe. The only difference is that we use the ROI() method in the draw() function to set the region of interest.
import hypermedia.video.*;
import java.awt.Rectangle;
OpenCV opencv;
void setup()
{
size( 640, 480 );
opencv = new OpenCV( this );
opencv.capture( 320, 240 );
opencv.cascade( OpenCV.CASCADE_FRONTALFACE_ALT );
}
void draw()
{
background( 0 );
opencv.read();
opencv.flip( OpenCV.FLIP_HORIZONTAL );
opencv.convert( GRAY );
opencv.ROI( 160, 0, 160, 240 );
scale( 2 );
image( opencv.image...