saving images with transparency from webcam capture

Core Library Questions

gesose

saving images with transparency from webcam capture

in Core Library Questions • 2 years ago

Hello Everyone!

This is my first post, I have used the resources quite often, but up until now I have been lucky with searching, but this time I have a problem.

I am trying to take an input from a webcam and do a background subtraction to capture movement. These images (one every second) then need to have a transparency added to them (I have tried alpha and tint). These images then need to be overlayed on one another to capture an hour's worth of movement through a space. This final image will be projected on a wall and change every second as the next second is captured.

What I have so far is the background subtraction and I am running into problems of changing opacity of the images. I am also lost on how to overlay 3600 (1 image per second for 1 hour) of these images. My first thoughts were to save out each image with transparency and then have another sketch pull these image to do the overlay. Can anybody help me with my problem or offer a better way of doing this?

Please forgive me as Processing is not my native tongue, I am an architecture student so I think more through other programs but have enough background with programming/scripting to understand the basics plus some.

Thanks in advance!

-Geoff

Replies(2)

clankill3r

Re: saving images with transparency from webcam capture

2 years ago

here's my attempt,

note that you see the difference the best in the beginning (which is logic).

If you want to see yourself after 5 minutes you have to stand still for a really long time.

What i did was adding the rgb values to 3 seperated int arrays.

Then those values devided to the frameCount gives the average color over time.

hope this will do.

import processing.video.*;
Capture cam;
int[] R = new int[320*240];
int[] G = new int[320*240];
int[] B = new int[320*240];
PImage timeIMG;
void setup() {
size(320, 240);
// If no device is specified, will just use the default.
cam = new Capture(this, 320, 240);
timeIMG = new PImage(320, 240);
}
void draw() {
if (cam.available() == true) {
cam.read();
addColor();
for(int i = 0; i < timeIMG.pixels.length; i++) {
int r = R[i]/frameCount;
int g = G[i]/frameCount;
int b = B[i]/frameCount;
timeIMG.pixels[i] = color(r, g, b);
}
timeIMG.updatePixels();
image(timeIMG, 0, 0);
//image(cam, 0, 0);
}
}
void addColor() {
cam.loadPixels();
for(int i = 0; i < cam.pixels.length; i++) {
int r = (cam.pixels[i] >> 16) & 0xFF; // Faster way of getting red(argb)
int g = (cam.pixels[i] >> 8) & 0xFF; // Faster way of getting green(argb)
int b = cam.pixels[i] & 0xFF; // Faster way of getting blue(argb)
R[i] += r;
G[i] += g;
B[i] += b;
}
}

gesose

Re: saving images with transparency from webcam capture

2 years ago

thanks a lot for the quick response clankill3r. i was able to get it working after i did a bit of editing. the final sketch makes all of the pixels that have "moved" pink and the rest become a grayscale image in the background.

-geoff

Top Reply