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Index › Programming Questions & Help › Other Libraries › RANGE OF a particular COLOR
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RANGE OF a particular COLOR (Read 1678 times)
pulse
RANGE OF a particular COLOR
Nov 29th, 2009, 5:19am  
You draw with a red marker on a white paper and capture a video. When you want to track the red marked sketch, I can only detet a particular value but I need to detect a range of red colors. Can any one guide to track a range of red values?
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Classiclll
Re: RANGE OF a particular COLOR
Reply #1 - Nov 29th, 2009, 7:18am  
you can use HSB mode instead of RGB mode.
on the HSB color space, it is relatively easy to define the distance representing the color similarity, i think.
like
http://www.geocities.jp/classiclll_newweb/SimilarColorProcessor4/applet/index.html
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pulse
Re: RANGE OF a particular COLOR
Reply #2 - Nov 30th, 2009, 7:58am  
Hi Classiclll,

Great, many thanks. Your example is quite good and advanced.

I am a beginer. Is there a simple way of tracking a range of colors?
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eskimoblood
Re: RANGE OF a particular COLOR
Reply #3 - Nov 30th, 2009, 8:35am  
Not tested but should work.

Code:

color cl1 = color(random(255),random(255),random(255));
color cl2 = color(random(255),random(255),random(255));

if(isIn(cl1.hue(), cl2.hue()) && isIn(cl1.saturation, cl2.saturation) && isIn(cl2.brightness, cl2.brightness)) {
	
}

boolean isIn(int value, int test){
	return value>test - 10 && value < test + 10; //10 is your range
}
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Andreas Köberle {eskimoblood}
222550793  
Classiclll
Re: RANGE OF a particular COLOR
Reply #4 - Nov 30th, 2009, 8:53am  
though it is a little heavy, i like

sqrt(pow(hue(a)-hue(b),2)+pow(saturation(a)-saturation(b),2)+pow(brightness(a)-b
rightness(b),2)) < tol

rather than

{abs(hue(a)-hue(2))+abs(..)+abs(..)}/3 < tol
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toxi
Re: RANGE OF a particular COLOR
Reply #5 - Nov 30th, 2009, 11:51am  
For what it's worth, here's an ancient color tracker class from 2003 for Processing ALPHA. The example won't run anymore without some changes to the Capture setup, but the VTracker class itself should be still usable:

http://toxi.co.uk/p5/vTracker/vTrackerCol.pde
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postspectacular.com | toxi.co.uk
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toxi
Re: RANGE OF a particular COLOR
Reply #6 - Nov 30th, 2009, 12:06pm  
Alternatively you might also want to look at the colorutils library and its TColor or Hue classes.

You could do something like: Code:

import toxi.color.*;
import toxi.math.*;

TColor trackColor=TColor.newRGB(#ff0000);
float tolerance= 0.5;
...
// check captured pixels
for(int y=0; y<height; y+=2) {
  for(int x=0; x<width; x+=2) {
    TColor col=TColor.newARGB(get(x,y));
    if(col.distanceToHSV(trackColor)<tolerance) {
      // bingo
    }
  }
}


TColor also can calc the distance in RGB or CMYK space and has a method to return the closest of the 12 major hues of the color wheel (getClosestHue()).

See:
https://dev.postspectacular.com/docs/colorutils/toxi/color/TColor.html
https://dev.postspectacular.com/docs/colorutils/toxi/color/Hue.html
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