UIImage as black and white

public byte[] MakeGrayScale(byte[] imageAsBytes)
		{
			UIImage image = ImageFromByteArray(imageAsBytes);
			var height = image.Size.Height;
			var width = image.Size.Width;

			var imageRect = new CGRect(0, 0, width, height);

			using (CGBitmapContext context = new CGBitmapContext(IntPtr.Zero,
												 (int)width, (int)height, 8,
																 0, CGColorSpace.CreateDeviceGray(),
																 CGImageAlphaInfo.None))
			{

				// draw the image
				context.DrawImage(imageRect, image.CGImage);

				UIKit.UIImage copyImage = UIKit.UIImage.FromImage(context.ToImage(), 0, image.Orientation);

				// save the image as a jpeg
				return copyImage.AsJPEG().ToArray();
			}
		}