public void ColorDodgeBlendOp2 ()
		{
			var lhs = GetSourceImage ("blend1.png");
			var rhs = GetSourceImage ("blend2.png");

			var lhs_wrap = new BitmapWrapper (lhs);
			var rhs_wrap = new BitmapWrapper (rhs);

			var op = new ColorDodgeBlendOp ();
			op.Apply (rhs_wrap, lhs_wrap);

			Compare (lhs, "colordodgeblend2.png");
		}
		/// <summary>
		/// Creates a new effect that will make the image look like a pencil sketch.
		/// </summary>
		/// <param name="pencilSize">Size of the pencil to use. Valid range is 1 - 20.</param>
		/// <param name="colorRange">Range of color to use. Valid range is -20 - 20.</param>
		public PencilSketchEffect (int pencilSize = 2, int colorRange = 0)
		{
			if (pencilSize < 1 || pencilSize > 20)
				throw new ArgumentOutOfRangeException ("pencilSize");
			if (colorRange < -20 || colorRange > 20)
				throw new ArgumentOutOfRangeException ("colorRange");

			this.pencil_size = pencilSize;
			this.color_range = colorRange;

			blur_effect = new GaussianBlurEffect (pencil_size);
			desaturate_op = new DesaturateOp ();
			invert_effect = new InvertColorsEffect ();
			bac_adjustment = new BrightnessContrastEffect (-color_range, -color_range);
			color_dodge_op = new ColorDodgeBlendOp ();
		}