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Color filter (Read 925 times)
avignon
Color filter
Oct 21st, 2007, 2:47am  
To make a color tracking application for the first time, i'm hacking http://www.roborealm.com/tutorial/color_object_tracking_2/slide010.php

It uses 'RGB filter' for extracting the target color area, yet due to my ignorance on image processing, I can't understand how exactly it works and how to implement it. Even though there are related pages...:
http://www.roborealm.com/help/RGB%20Filter.php
http://www.roborealm.com/help/Color_Filter.php
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antiplastik
Re: Color filter
Reply #1 - Oct 26th, 2007, 1:41pm  
you'll first need to extract red, green and blue components of each pixel of your image :

Code:
int c = img[myPixel];
int r = red(c);
int g = green(c);
int b = blue(e);


here is another way to do it, using shift and bit mask, which are faster instructions (same result) :
Code:
int c = img[myPixel];
int r = c >> 16 & 0xFF;
int g = c >> 8 & 0xFF;
int b = c & 0xFF;


then, apply the given formula :
Code:

// blue filter :
b = (b - r) + (b - g);
r = 0;
g = 0;
// output :
c = color(r, g, b);
pixels[myPixel] = c;


this should be a good starting point. you can enhance your code with normalization stuff etc., as said in the tutorial.
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