Tuesday, March 15, 2011

C# Tutorial - Image Editing: Saving, Cropping, and Resizing

http://www.switchonthecode.com/tutorials/csharp-tutorial-image-editing-saving-cropping-and-resizingIn C# it can be tiresome to do certain image editing functions using GDI+. This post has some fun editing methods which can come in handy at times. I have also included a nice little C# program to show all the functionality of the methods below.

Saving a Jpeg

The first thing to do here is set up the method signature with the input parameters. These are the save file path (string), the Image to save (System.Drawing.Bitmap), and a quality setting (long).
private void saveJpeg(string path, Bitamp img, long quality)
The next few things to do are setting up encoder information for saving the file. This includes setting an EncoderParameter for the quality of the Jpeg. The next thing is to get the codec information from your computer for jpegs. I do this by having a function to loop through the available ones on the computer and making sure jpeg is there. The line under that makes sure that the jpeg codec was found on the computer. If not it just returns out of the method.
The last thing to do is save the bitmap using the codec and the encoder infomation.
private void saveJpeg(string path, Bitmap img, long quality)
   // Encoder parameter for image quality
   EncoderParameter qualityParam = new EncoderParameter(Encoder.Quality, quality);

   // Jpeg image codec
   ImageCodecInfo jpegCodec = this.getEncoderInfo("image/jpeg");

   if(jpegCodec == null)

   EncoderParameters encoderParams = new EncoderParameters(1);
   encoderParams.Param[0] = qualityParam;

   img.Save(path, jpegCodec, encoderParams);

private ImageCodecInfo getEncoderInfo(string mimeType)
   // Get image codecs for all image formats
   ImageCodecInfo[] codecs = ImageCodecInfo.GetImageEncoders();

   // Find the correct image codec
   for (int i = 0; i < codecs.Length; i++)
      if (codecs[i].MimeType == mimeType)
         return codecs[i];
   return null;