Resize the image

We can start with a byte array which contains the image data loaded from either a database or file. We can then resize the bitmap using a number of System.Drawing methods and finally save the bitmap to an output stream. In this case the output stream is the Response output stream

System.IO.MemoryStream memoryStream = new System.IO.MemoryStream( byteArray );
System.Drawing.Image image = System.Drawing.Image.FromStream( memoryStream );
System.Drawing.Image thumbnail = new Bitmap( newWidth, newHeight );
System.Drawing.Graphics graphic = System.Drawing.Graphics.FromImage( thumbnail );

graphic.InterpolationMode = InterpolationMode.HighQualityBicubic;
graphic.SmoothingMode = SmoothingMode.HighQuality;
graphic.PixelOffsetMode = PixelOffsetMode.HighQuality;
graphic.CompositingQuality = CompositingQuality.HighQuality;

graphic.DrawImage(image, 0, 0, newWidth, newHeight);                

if( contentType == "image/gif" )
{
  using ( thumbnail )
  {
        OctreeQuantizer quantizer = new OctreeQuantizer ( 255 , 8 ) ;
        using ( Bitmap quantized = quantizer.Quantize ( bitmap ) )
        {
            Response.ContentType = "image/gif";
            quantized.Save ( Response.OutputStream , ImageFormat.Gif ) ;
        }
    }
}


if(  contentType == "image/jpeg" )
{
    info = ImageCodecInfo.GetImageEncoders();
    EncoderParameters encoderParameters;
    encoderParameters = new EncoderParameters(1);
    encoderParameters.Param[0] = new EncoderParameter(Encoder.Quality, 100L);
    Response.ContentType = "image/jpeg";
    thumbnail.Save(Response.OutputStream, info[1], encoderParameters);
}