/// <summary>
/// Inserts Gaussian noise into a bitmap.
/// </summary>
/// <param name="source">Bitmap to be processed</param>
/// <param name="amount">Standard deviation of perturbation for each color channel.</param>
/// <returns>New, speckled bitmap</returns>
/// <remarks>
/// This code uses Bitmap.GetPixel and SetPixel methods for clarity. An implementation using Bitmap.LockBits
/// and then directly modifying the image data may be faster, espectially for large images.
/// </remarks>
public static Bitmap AddNoise(this Bitmap source, double amount)
{
if (source == null)
throw new ArgumentNullException("source");
Bitmap bitmap = null;
Bitmap tempBitmap = null;
try
{
var generator = new GaussianRandom(0.0, amount, SampleUtilities.MakeRandomSeed());
tempBitmap = new Bitmap(source.Width, source.Height);
for (int y = 0; y < tempBitmap.Height; y++)
{
for (int x = 0; x < tempBitmap.Width; x++)
{
var pixel = source.GetPixel(x, y);
Color newPixel = AddPixelNoise(pixel, generator);
tempBitmap.SetPixel(x, y, newPixel);
}
}
bitmap = tempBitmap;
tempBitmap = null;
}
finally
{
if (tempBitmap != null) tempBitmap.Dispose();
}
return bitmap;
}
static Color AddPixelNoise(Color pixel, GaussianRandom generator)
{
int newR = (int)pixel.R + generator.NextInteger();
int newG = (int)pixel.G + generator.NextInteger();
int newB = (int)pixel.B + generator.NextInteger();
int r = Math.Max(0, Math.Min(newR, 255));
int g = Math.Max(0, Math.Min(newG, 255));
int b = Math.Max(0, Math.Min(newB, 255));
return Color.FromArgb(r, g, b);
}
