title: Cropping a bitmap gives an empty bitmap
body: <p>I've taken a code from here (SO) that crops images. I tried it on bitmaps containing black text on white font. The result i get in return is a completely white output with no content.</p>
  
  <pre><code>        // create new bitmap with desired size and same pixel format
          Bitmap croppedBitmap = new Bitmap(rect.Width, rect.Height, bitmap.PixelFormat);
  
          // create Graphics "wrapper" to draw into our new bitmap
          // "using" guarantees a call to gfx.Dispose()
          using (Graphics gfx = Graphics.FromImage(croppedBitmap))
          {
              // draw the wanted part of the original bitmap into the new bitmap
              gfx.DrawImage(bitmap, 0, 0, rect, GraphicsUnit.Pixel);
          }
  
          return croppedBitmap;
  </code></pre>
  
  <p>Any guess?</p>
  
  <p><strong>PS</strong> if i crop in paint of course it does work</p>
  
  <p><strong>edit</strong></p>
  
  <p>If I crop a picture of me for example it works....</p>
  
  <p><strong>Appendix</strong></p>
  
  <p>Code:</p>
  
  <p><strong>Rectangles</strong>:</p>
  
  <pre><code>        Rectangle 1: 8 50, 95, 80, 30 // invoice number
          Rectangle 2: 625, 778, 475, 22 // Total amount
  </code></pre>
  
  <p><strong>CropImage():</strong></p>
  
  <pre><code>    public static Bitmap CropImage(Bitmap bitmap, Rectangle rect)
      {
          Bitmap croppedBitmap = new Bitmap(rect.Width, rect.Height, bitmap.PixelFormat);
  
          using (Graphics gfx = Graphics.FromImage(croppedBitmap))
          {
              gfx.DrawImage(bitmap, 0, 0, rect, GraphicsUnit.Pixel);
          }
  
          return croppedBitmap;
      }
  </code></pre>
  
  <p>Image:
  (Sensitive data is hidden, I only left the part I'm trying to crop)
  <a href="http://img33.imageshack.us/img33/5703/modelx.png" rel="nofollow">http://img33.imageshack.us/img33/5703/modelx.png</a></p>