Calculate and compare the amount of two colours in a video

Core Library Questions

nathanoga..

Calculate and compare the amount of two colours in a video

in Core Library Questions • 1 month ago

Hello all,

I'm trying to detect, calculate and compare the amount of two colours present in a webcam feed.

something similar to what is being done here http://forum.processing.org/topic/compare-measurement-of-x-color-pixels-compared-to-background. Except I would like to use coloured cards, say red and green, and by holding them up to the camera being able to tell which is more prominent in the video - and from their calculating the ratio.

I'm not completely sure how to implement this with a video feed from a webcam and i'm just looking for some advice on how to go about the logic. Any input or direction to something similar would be greatly appreciated.

many thanks

Replies(2)

tfguy44

Re: Calculate and compare the amount of two colours in a video

1 month ago

This sort of a sketch has several steps:

1) Get a webcam feed working.
2) Learn about the pixels array and how colors work.

3) Decide what you mean by "red" and "green".
4) Do some looping.

Let's start at the top. Do you have a working webcam, and can you display it's image inside a sketch?

nathanoga..

Re: Calculate and compare the amount of two colours in a video

1 month ago

Thanks for the response, here is what I have so far

import processing.video.*;
Capture cam;
//colors to look for
color trackColor;
int colorCount=0;
boolean click= false;
void setup() {
size(640, 480);
String[] cameras = Capture.list();
cam = new Capture(this, cameras[0]);
cam.start();
}
void draw() {
if (cam.available() == true) {
cam.read();
}
image(cam, 0, 0);
cam.loadPixels();
if(click){
for(int i = 0; i<cam.width*cam.height;i++){
if( cam.pixels[i]==trackColor)
{
colorCount++;
}
if(i == (cam.width*cam.height)-1){
println(colorCount); //get amount of pixels of this colour in the frame
float colorRatio = (colorCount/(cam.width*cam.height))*100; //get ratio of colour in relation to image: (colorPixels/All the pixels) *100
println(colorRatio); // always returns 0, not sure why.
colorCount = 0;
}
}
}
cam.updatePixels();
}
void mousePressed(){
color c = get(mouseX, mouseY);
int loc = mouseX + mouseY*cam.width;
trackColor = cam.pixels[loc];
click = true;
}

What I have managed to do is track the amount of pixels of a given colour in every frame.

When I try to convert this to a ratio of all the pixels in the frame I always get 0, this could be a really rookie mistake on my side or something to do with floating point calculations. I have never really worked with so many decimal places before.

I also don't know if this is the most efficient way to do this whole operation either.

The other thing I could use your input on is how I would go about checking to see if a range of a specific colour is present.

My final goal is to have a whole bunch of red and green (for example) paddles and be able tell which color is more prominent which would correspond to the amount of paddles present in the image.

Oh and taking into account distance - i do understand that if some are closer they will take up more space.

really appreciate your help

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