/// <summary>
///
/// </summary>
/// <param name="image"></param>
/// <returns>Image in gray scale</returns>
private static Bitmap ConvertToGrayScale(Bitmap image)
{
if (image != null)
{
return(RGB2GrayScale.Luma(image));
}
else
{
throw new ArgumentNullException("Cannot convert to gray scale null reference object");
}
}
/// <summary>
///
/// </summary>
/// <param name="bitmap">Image to shade</param>
/// <param name="c1">The lighter color used for shading. White by default.</param>
/// <param name="c2">The darker color used for shading. Black by default</param>
/// <returns></returns>
public static Bitmap TwoColoredShading(Bitmap bitmap, Color?c1 = null, Color?c2 = null)
{
Color c;
// assign default values
Color color1 = (c1 == null) ? Color.White : (Color)c1;
Color color2 = (c2 == null) ? Color.Black : (Color)c2;
//Convert to gray scale
Bitmap img = RGB2GrayScale.Luma(bitmap);
// longer side of the image
int longerSide = (bitmap.Height > bitmap.Width) ? bitmap.Height : bitmap.Width;
// depth of hilber curve
int depth = (int)Math.Ceiling(Math.Log(longerSide, 2.0));
Curve.initial_size = 2 << depth - 1;
// Represents hilbert curve coordinates
Curve curve = Hilbert.Discretization(depth);
float [,] pixels_brightness = GetPixelsBrightness(bitmap);
byte pixel;
double E = 0;
int x, y;
for (int i = 0; i < curve.Length; i++)
{
x = (int)curve.X[i];
y = (int)curve.Y[i];
if (y < img.Height && x < img.Width)
{
if (pixels_brightness[y, x] + E <= 0.5)
{
pixel = 0;
}
else
{
pixel = 1;
}
E = pixels_brightness[y, x] - pixel + E;
c = (pixel > 0) ? color1 : color2;
img.SetPixel(x, y, c);
}
}
return(img);
}
