euglena/lib/video/examples/Capture/BackgroundSubtraction/BackgroundSubtraction.pde
2016-07-10 00:36:44 -07:00

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/**
* Background Subtraction
* by Golan Levin.
*
* Detect the presence of people and objects in the frame using a simple
* background-subtraction technique. To initialize the background, press a key.
*/
import processing.video.*;
int numPixels;
int[] backgroundPixels;
Capture video;
void setup() {
size(640, 480);
// This the default video input, see the GettingStartedCapture
// example if it creates an error
//video = new Capture(this, 160, 120);
video = new Capture(this, width, height);
// Start capturing the images from the camera
video.start();
numPixels = video.width * video.height;
// Create array to store the background image
backgroundPixels = new int[numPixels];
// Make the pixels[] array available for direct manipulation
loadPixels();
}
void draw() {
if (video.available()) {
video.read(); // Read a new video frame
video.loadPixels(); // Make the pixels of video available
// Difference between the current frame and the stored background
int presenceSum = 0;
for (int i = 0; i < numPixels; i++) { // For each pixel in the video frame...
// Fetch the current color in that location, and also the color
// of the background in that spot
color currColor = video.pixels[i];
color bkgdColor = backgroundPixels[i];
// Extract the red, green, and blue components of the current pixel's color
int currR = (currColor >> 16) & 0xFF;
int currG = (currColor >> 8) & 0xFF;
int currB = currColor & 0xFF;
// Extract the red, green, and blue components of the background pixel's color
int bkgdR = (bkgdColor >> 16) & 0xFF;
int bkgdG = (bkgdColor >> 8) & 0xFF;
int bkgdB = bkgdColor & 0xFF;
// Compute the difference of the red, green, and blue values
int diffR = abs(currR - bkgdR);
int diffG = abs(currG - bkgdG);
int diffB = abs(currB - bkgdB);
// Add these differences to the running tally
presenceSum += diffR + diffG + diffB;
// Render the difference image to the screen
pixels[i] = color(diffR, diffG, diffB);
// The following line does the same thing much faster, but is more technical
//pixels[i] = 0xFF000000 | (diffR << 16) | (diffG << 8) | diffB;
}
updatePixels(); // Notify that the pixels[] array has changed
println(presenceSum); // Print out the total amount of movement
}
}
// When a key is pressed, capture the background image into the backgroundPixels
// buffer, by copying each of the current frame's pixels into it.
void keyPressed() {
video.loadPixels();
arraycopy(video.pixels, backgroundPixels);
}