Can not change DPI of JPG image. #92

public byte[] GetImage(Stream sourceStream, string contentType, double targetDPI)
{
	MemoryStream outputStream = new MemoryStream();
	try
	{
		using (sourceStream)
		{
			Image image = new Image(sourceStream);
			double currentDPI = image.HorizontalResolution;		
			double resizeRatio = targetDPI / currentDPI;
			int targetWidth = (int)Math.Round((image.Width * resizeRatio)); 
			int targetHeight = (int)Math.Round((image.Height * resizeRatio));
			image.HorizontalResolution = targetDPI;
			image.VerticalResolution = targetDPI;
			BicubicResampler resampler = new BicubicResampler();
			switch (contentType)
			{
				case "image/gif":
					GifEncoder gifEncoder = new GifEncoder();
					gifEncoder.Quality = 256;
					image.Resize(targetWidth, targetHeight, resampler, false).Save(outputStream, gifEncoder);
					break;
				case "image/jpeg":
					JpegEncoder jpegEncoder = new JpegEncoder();
					jpegEncoder.Quality = 100;
					image.Resize(targetWidth, targetHeight, resampler, false).Save(outputStream, jpegEncoder);
					break;
				default:
					PngEncoder pngEncoder = new PngEncoder();
					image.Resize(targetWidth, targetHeight, resampler, false).Save(outputStream, pngEncoder);
					break;
			}
		}
	}
	catch (Exception ex)
	{
		new LoggerExtensions().LogException(ex, "Brand Central Station: Image Extensions");
		return new byte[0];
	}
	return outputStream.ToArray();
}