title: Is there a quicker way to apply brightness in OpenCV?
body: <p>In my application I have the following code which changes the brightness of a pixel by 20.</p>
  
  <pre><code>    for( int y = 0; y &lt; src.rows; y++ )
      { 
          for( int x = 0; x &lt; src.cols; x++ )
          { 
              for( int c = 0; c &lt; 3; c++ )
              {
                  src.at&lt;cv::Vec3b&gt;(y,x)[c] = cv::saturate_cast&lt;uchar&gt;( ( src.at&lt;cv::Vec3b&gt;(y,x)[c] ) + 20 );
              }
          }
      }
  </code></pre>
  
  <p>Is there a more efficient way of applying this effect?</p>