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openCV quickie (Read 3266 times)
sam_mcelhinney
openCV quickie
Mar 14th, 2009, 10:39am  
all,
this should be easy to solve:

i'm trying to load up all the pixels from one video feed in open cv, into an integer array so that i can cycle through them with a for loop...

something like this color filter i wrote; but it won't work; i'm obviously using the wrong code in the first line to load up the pixels.

how do i do this? sure it must be simple enough...
s




void colorFilter(){
 int[] img =  opencv.image(); //get the normal image of the camera
 
 float r,g,b;
 loadPixels();

 if (filtering){
  for(int i=0;i<width*height;i++){ //loop through all the pixels
   float rval = red(img[i]);
   float gval = green(img[i]);
   float bval = blue(img[i]);
 
   r = sampleR*((bval - rval) + (bval - bval));
   g = sampleG*((bval - rval) + (bval - bval));
   b = sampleB*((bval - rval) + (bval - gval));
   pixels[i] = color(r,g,b); //draw each pixel to the screen
 }}
else {
 for(int i=0;i<width*height;i++){ //loop through all the pixels
   float rval = red(img[i]);
   float gval = green(img[i]);
   float bval = blue(img[i]);
 
  r = rval;
  g = gval;
  b = bval;
  pixels[i] = color(r,g,b); //draw each pixel to the screen
}}  
 updatePixels();
}
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RickiG
Re: openCV quickie
Reply #1 - Mar 19th, 2009, 10:30am  
The loadPixels() pull the pixels currently on the screen if you want the pixels from the openCV image you could either: put the image on screen with image(opencv.image(), 0, ) and the do loadPixels();
or, if you don't need to display the image, do opencv.image().loadPixels()
manipulate the pixels as you need to and then call opencv.image().updatePixels()
and the display it with: image(opencv.image(), 0, )

hope it did the trick
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Regards Ricki
 
sam_mcelhinney
Color Filter for openCV
Reply #2 - Mar 20th, 2009, 11:38am  
this now works; provides a color filter system for openCV images.

click on the color to start a filter for it
works particularly well for blue

s

Quote:
//Sam McElhinney

import hypermedia.video.*;
color colorSample = color (255,255,255);
float  sampleR;
float  sampleG;
float  sampleB;
boolean filtering = false;
OpenCV opencv;
 
void setup(){
  size(320,240);
  opencv = new OpenCV( this );  
  opencv.capture(width,height);
}

void draw(){
  opencv.read();
  colorFilter();
}
    
//COLOR FILTER
void colorFilter(){
  image(opencv.image(), 0, 0);
  loadPixels();
if (filtering){
   for(int i=0;i<width*height;i++){ //loop through all the pixels
    float rval = red(pixels[i]);
    float gval = green(pixels[i]);
    float bval = blue(pixels[i]);
    float r;
    float g;
    float b;
    r = sampleR*((bval - rval) + (bval - bval)); 
    g = sampleG*((bval - rval) + (bval - bval));
    b = sampleB*((bval - rval) + (bval - gval)); 
    pixels[i] = color(r,g,b); //draw each pixel to the screen
  }}
else {
  for(int i=0;i<width*height;i++){ //loop through all the pixels
    float rval = red(pixels[i]);
    float gval = green(pixels[i]);
    float bval = blue(pixels[i]);
    float r;
    float g;
    float b;
    r = rval; 
    g = gval;
    b = bval; 
    pixels[i] = color(r,g,b); //draw each pixel to the screen
}}  
  updatePixels();
}

void mousePressed(){
  int loc = mouseX + mouseY*width;
  colorSample = pixels[loc];
  sampleR = red(colorSample);
  sampleG = green(colorSample);
  sampleB = blue(colorSample);
  filtering = !filtering;
}

void keyPressed(){
  filtering = false;
}

public void stop(){
  opencv.stop();//stop the object
  super.stop();
}
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sam_mcelhinney
Re: openCV quickie
Reply #3 - Mar 20th, 2009, 1:44pm  
hey ricki

one last point - it is a bit odd - maybe i am doing something wrong
when i use your commands:

opencv.image().loadPixels();
opencv.image().updatePixels();

instead of the usual loadPixels and updatePixels (ie when i just want to selectively load up the pixels in the opencv image)

it comes back with a null pointer error when cycling through the pixel array - so it isn't loading up properly

any thoughts? do i have something wrong there? it would be a lot handier to just load up the opencv image pixels without having to display them!

best

s
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sam_mcelhinney
Re: openCV quickie
Reply #4 - Mar 20th, 2009, 2:49pm  
ok
i have solved it myself...

Quote:
//Sam McElhinney

import hypermedia.video.*;
color colorSample = color (255,255,255);
float  sampleR;
float  sampleG;
float  sampleB;
int cam_width;
int cam_height;
int comb_width;
int comb_height;
int x = 10;
int y = 10;
boolean filtering = false;
OpenCV opencv;
 
void setup(){
  size(320,480);
  cam_width = 320-x;
  cam_height = 240-y;
  comb_width = cam_width;
  comb_height = 2*cam_height;
  opencv = new OpenCV( this );  
  opencv.capture(cam_width,cam_height);
}

void draw(){
  opencv.read();
  colorFilter();
}
    
//COLOR FILTER
void colorFilter(){
  
  int[] cam =  opencv.pixels();
  loadPixels();
if (filtering){
   for(int i=0;i<cam_width*cam_height;i++){ //loop through all the camera pixels
    float rval = red(cam[i]);
    float gval = green(cam[i]);
    float bval = blue(cam[i]);
    float r;
    float g;
    float b;
    r = sampleR*((bval - rval) + (bval - bval)); 
    g = sampleG*((bval - rval) + (bval - bval));
    b = sampleB*((bval - rval) + (bval - gval)); 
    cam[i] = color(r,g,b); //change each pixel
   }}
    
else {
  for(int i=0;i<cam_width*cam_height;i++){ //loop through all the camera pixels
    float rval = red(cam[i]);
    float gval = green(cam[i]);
    float bval = blue(cam[i]);
    float r =0;
    float g = 0;
    float b =0;
    r = rval; 
    g = gval;
    b = bval; 
    cam[i] = color(r,g,b);  // dont change each pixel
}}  
 updatePixels();
 
 PImage comb = createImage(comb_width, comb_height, RGB);
   comb.loadPixels();
   for (int i = 0; i < comb_width*comb_height/2; i++) {
      comb.pixels[i] = cam [i];
    }
   for (int i = comb_width*comb_height/2; i < comb_width*comb_height; i++) {
      comb.pixels[i] = cam [i-comb_width*comb_height/2];
    } 
   comb.updatePixels();
   image(comb,5,5);
}

void mousePressed(){
  int loc = mouseX + mouseY*width;
  colorSample = pixels[loc];
  sampleR = red(colorSample);
  sampleG = green(colorSample);
  sampleB = blue(colorSample);
  filtering = !filtering;
}

void keyPressed(){
  filtering = false;
}

public void stop(){
  opencv.stop();//stop the object
  super.stop();
}
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