(Ruby Sample Code) Basic Motion Detection With OpenCV

opencv_test.rb

require 'opencv'
include OpenCV

camera = CvCapture.open #open camera

#set the video size to 512x288
camera.width = 512
camera.height = 288

window = GUI::Window.new 'Camera'

sleep 3

#convert to grayscale
firstFrame = camera.query.BGR2GRAY
firstFrame = firstFrame.smooth CV_GAUSSIAN, 21, 21, 0

while not GUI::wait_key 1
    frame = camera.query
    gray = frame.BGR2GRAY
    gray = gray.smooth CV_GAUSSIAN, 21, 21, 0

    frameDelta = firstFrame.abs_diff gray
    thresh = frameDelta.threshold 25, 255, CV_THRESH_BINARY
    thresh = thresh.dilate nil, 2
    cnts = thresh.find_contours(:mode => CV_RETR_EXTERNAL, :method => CV_CHAIN_APPROX_SIMPLE)
    
    while cnts
        if cnts.contour_area < 500
            cnts = cnts.h_next
            next
        end

        frame.put_text!("Motion Detected", CvPoint.new(10, 20), CvFont.new(:simplex), CvColor::Red)
        cnts = cnts.h_next
    end

    window.show frame
end