Thursday, February 10, 2011

Resizing an image in c# without losing lower an right pixel-parts

I have a c#-class that looks roughly like this:

 class ImageContainer
 {
  Image image;
  internal ImageContainer getResized(int width, int height)
  {
   Bitmap bmp = new Bitmap(width, height);
   //Create a System.Drawing.Graphics object from the Bitmap which we will use to draw the high quality scaled image
   System.Drawing.Graphics gr = System.Drawing.Graphics.FromImage(bmp);
   //Set the System.Drawing.Graphics object property SmoothingMode to HighQuality
   gr.SmoothingMode = System.Drawing.Drawing2D.SmoothingMode.HighQuality;
   //Set the System.Drawing.Graphics object property CompositingQuality to HighQuality
   gr.CompositingQuality = System.Drawing.Drawing2D.CompositingQuality.HighQuality;
   //Set the System.Drawing.Graphics object property InterpolationMode to High
   gr.InterpolationMode = System.Drawing.Drawing2D.InterpolationMode.HighQualityBicubic;
   //Draw the original image into the target Graphics object scaling to the desired width and height
   System.Drawing.Rectangle rectDestination = new System.Drawing.Rectangle(0, 0, width, height);
   gr.DrawImage(image, rectDestination, 0, 0, image.Width, image.Height, GraphicsUnit.Pixel);
   //dispose / release  resources

   ImageContainer ic = new ImageContainer();
   ic.image = bmp;

   return ic;
  }
 }

The resizing works fine, but DrawImage doesn't draw the most right an lower pixel-fragments when scaling down an image.

  • the problem is solved by

    gr.PixelOffsetMode = System.Drawing.Drawing2D.PixelOffsetMode.HighQuality;
    

    :)

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