title: Scalar(0,255,0) does not give green colored line in opencv
body: <p>I'm trying to draw gradient lines on an image. I want my lines to be green colored and I use Scalar(0,255,0). Still, I'm getting only black color. For Scalar(0,0,0) also I'm getting black. For Scalar(255,255,255) I get white, but no other color for any combination. Part of the code is given below:</p>
  
  <pre><code>line(visual_image,
       Point(x1*scaleFactor, y1*scaleFactor),
       Point(x2*scaleFactor, y2*scaleFactor),
       Scalar(0,255,0),
       1,8,0);
  </code></pre>