What is the best way to detect white color? [closed]

Question

I'm trying to detect white objects in a video. The first step is to filter the image so that it leaves only white-color pixels. My first approach was using HSV color space and then checking for high level of VAL channel. Here is the code:

//convert image to hsv
cvCvtColor( src, hsv, CV_BGR2HSV );
cvCvtPixToPlane( hsv, h_plane, s_plane, v_plane, 0 );

for(int x=0;x<srcSize.width;x++){
  for(int y=0;y<srcSize.height;y++){
    uchar * hue=&((uchar*) (h_plane->imageData+h_plane->widthStep*y))[x];
    uchar * sat=&((uchar*) (s_plane->imageData+s_plane->widthStep*y))[x];
    uchar * val=&((uchar*) (v_plane->imageData+v_plane->widthStep*y))[x];

    if((*val>170))
      *hue=255;
    else
      *hue=0;
  }
}

leaving the result in the hue channel. Unfortunately, this approach is very sensitive to lighting. I'm sure there is a better way. Any suggestions?

Answer 1

Why are you using HSV? It would make more sense to convert to HSL and use the luminance channel. Of course you will not get only white, but every color with high luminance over a threshold. After all, you can't rely on pure white unless your source image has been overexposed.