Obtaining the frame difference

To begin with, we create a patch with name Frame001.pd. Put in all those elements for displaying the live webcam image in a rectangle. We use a dimen 800 600 message for the gemwin object to show the GEM window in 800 x 600 pixels. We plan to display the video image in the full size of the window.

From Chapter 2, Computer Graphics with the GEM Library, we understood that a square of size 4 x 4 occupied the default GEM window. The aspect ratio of the current GEM window is now 4:3. We use a rectangle of size 5.33 x 4 (4:3 aspect ratio) to cover the whole GEM window:

Now we have one single frame of the video image. To make a comparison with another frame, we have to store that frame in memory. In Chapter 3, Image Processing, we learned the use of the pix_buffer object. We can store a frame by using pix_buffer_write and retrieve it for comparison by using pix_buffer_read. In the following patch, you can click on the bang box to store a copy of the current video frame...