title: CV_8UC1 to CV_32FC1 conversion in OpenCV
body: <p>the way we convert the image type from <code>CV_8UC1</code> to <code>CV_32FC1</code> in OpenCV with C++ API is</p>
  
  <pre><code>        r1.convertTo(r1, CV_32FC1, 1.0/255.0);
  </code></pre>
  
  <p>where <code>r1</code> is the matrix declared as <code>cv::Mat</code>. 
  Can anybody tell me how to convert from <code>CV_8UC1</code> to <code>CV_32FC1</code> type in OpenCV with C API? If <code>r2</code> is a matrix described as <code>CvMat* r2</code>.</p>