OpenCV and Processing 14

This example continues to explore the Video module in OpenCV. It uses one of the BackgroundSubtractors, the BackgroundSubtractorKNN. It learns the motion in front of the camera and treats the stationary scene as background.

In the code, the important command is

bkg.apply(frame, fgmask);

The subtractor object bkg takes in the latest frame and generates a foreground mask, fgmask. We can use the foreground mask to single out the foreground moving object.

Here are a number of screen shots from the testing. The background is the planet Earth image from NASA.

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OpenCV and Processing 13

In this example, we move on to the Video module of OpenCV 3.0.0. The first function we test is the Dense Optical Flow. It demonstrates the use of the calcOpticalFlowFarneback function. Again it makes use of the previous CVImage object to bridge between the Processing PImage and OpenCV Mat. The example also reduces the size of the video (using the variable factor) before sending it for the optical flow processing; otherwise, the process can be lengthy.

The optical flow process will basically compare two consecutive frames (the Mat last and grey) from the live webcam video. It will try to compute where the current pixels move to in the new frame.

Here are a number of screen shots from the sample run.

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