/// <summary>
/// Computes the center moments for the specified image.
/// </summary>
///
/// <param name="image">The image whose moments should be computed.</param>
/// <param name="area">The region of interest in the image to compute moments for.</param>
///
public override void Compute(float[,] image, Rectangle area)
{
RawMoments raw = new RawMoments(image, area, Order);
CentralMoments center = new CentralMoments(raw);
this.Compute(center);
}
/// <summary>
/// Computes the Hu moments from the specified central moments.
/// </summary>
///
/// <param name="moments">The central moments to use as base of calculations.</param>
///
public void Compute(CentralMoments moments)
{
double inv = 1.0 / moments.Mu00;
double inv2 = 1.0 / (moments.Mu00 * moments.Mu00);
double inv5d2 = Math.Sqrt(inv2 * inv2 * inv);
float n20 = (float)(moments.Mu20 * inv2);
float n02 = (float)(moments.Mu02 * inv2);
float n11 = (float)(moments.Mu11 * inv2);
float n21 = (float)(moments.Mu21 * inv5d2);
float n12 = (float)(moments.Mu12 * inv5d2);
float n30 = (float)(moments.Mu30 * inv5d2);
float n03 = (float)(moments.Mu03 * inv5d2);
// (η20 + η02)
I1 = (n20 + n02);
// (η20 − η02)² + 4 η11²
I2 = (n20 - n02) * (n20 - n02) + 4 * (n11 * n11);
// (η30 − 3 η12)²
I3 = (n30 - 3 * n12) * (n30 - 3 * n12)
// + (3 η21 − η03)²
+ (3 * n21 - n03) * (3 * n21 - n03);
// (η30 + η12)² + (η21 + η03)²
I4 = (n30 + n12) * (n30 + n12) + (n21 + n03) * (n21 + n03);
// (η30 − 3 η12) (η30 + η12) [(η30 + η12)² −3 (η21 + η03)² ]
I5 = (n30 - 3 * n12) * (n30 + n12) * ((n30 + n12) * (n30 + n12) - 3 * (n21 + n03) * (n21 + n03))
// (3 η21 − η03) (η21 + η03) [3 (η30 + η12)² − (η21 + η03)² ]
+ (3 * n21 - n03) * (n21 + n03) * (3 * (n30 + n12) * (n30 + n12) - (n21 + n03) * (n21 + n03));
// (η20 − η02) [(η30 + η12)² − (η21 + η03)² ]
I6 = (n20 - n02) * ((n30 + n12) * (n30 + n12) - (n21 + n03) * (n21 + n03))
// + 4 η11 (η30 + η12) (η21 + η03)
+ 4 * n11 * (n30 + n12) * (n21 + n03);
// (3 η21 − η03) (η30 + η12) [(η30 + η12)² − 3 (η21 + η03)² ]
I7 = (3 * n21 - n03) * (n30 + n12) * (n30 + n12) * ((n30 + n12) * (n30 + n12) - 3 * (n21 + n03) * (n21 + n03))
// - (η30 − 3 η12) (η21 + η03) [3 (η30 + η12)² − (η21 + η03)² ]
- (n30 - 3 * n12) * (n21 + n03) * (3 * (n30 + n12) * (n30 + n12) - (n21 + n03) * (n21 + n03));
}