title: HSV conversion with cvCvtColor() issue
body: <p>I'm trying convert RGB image to HSV with the function cvCvtColor(), but the results are unexpected. For example, white are converted to something near to red. </p>
  
  <pre><code>        cvCvtColor(img, hsv, CV_BGR2HSV);
          cvSplit( hsv, h, s, v, NULL );
          cvInRangeS(h,cvScalar(0,0,0,0),cvScalar(20,0,0,0),imgthresh);  
          cvShowImage("image", img);
          cvShowImage("hsv", hsv);
          cvShowImage("threshold", imgthresh);
  </code></pre>
  
  <p>Is the image converted correctly and only displayed wrong? 
  And about the threshold, the better way to do this is using the 3 channels or only the hue?
  I want track red objects.
  Sorry about the english.
  Thanks.</p>