mirroring web cam image?

Xeronimo74

What's the best/quickest way to get the web cam image mirrored so that it mirrors your movements?

Creating a new PImage and looping through the original pixels, 'moving them from left to right'? scale(-1,1) is not an option in this case since I want to use, and refer to, the pixels from the web cam image.

jeremydouglass

Normally scale(-1,1); image(cam); is the easiest.

If you can't use scale(), just loop through pixels using a nested loop with your x loop run backwards. Increment the pixel offset counter by width each y loop line, decrement back down 1 px at a time until width times in the inner loop.

Alternately, call scale(-1,1) and then loop through pixels[] in normal order with a non-nested loop, as per the standard example. Modify values as needed. This code approach is also much easier to read!

• https://processing.org/reference/pixels.html

Re:quickest, try both approaches and benchmark. They should both be fast, but results can sometimes be surprising.

You mention "creating a new PImage" -- that shouldn't be necessary in either case.

P.S. Why is this under "Library Questions"?

Xeronimo74

It was under 'library questions' because something went wrong. I've corrected it.

Regarding scale(), wouldn't it have to be image(cam,-width, 0); then?

How would I modify it without a non-nested loop?

Right now I'm doing it like this:

void flipImage() {
  img.loadPixels();
  movie.loadPixels();
  for (int y = 0; y<height; y++) {
    for (int x = 0; x<width; x++) {
      img.pixels[y*width+x] = movie.pixels[y*width+(width-1-x)];
    }
  }
  img.updatePixels();
}

And I'm creating a PImg called 'img' because I want to sample info from it later on (and not from 'movie', because 'movie' is not mirrored correctly).