using System;

using System.Collections.Generic;

using System.Linq;

using System.Numerics;

using System.Text;

using System.Threading.Tasks;

​

namespace KassWitkinBandPassFilterTest

{

    public class KassWitkin

    {

        private static double tx(double centerX, double theta)

        {

            return centerX * Math.Cos(theta);

        }

​

        private static double ty(double centerY, double theta)

        {

            return centerY * Math.Sin(theta);

        }

​

        private static double u_star(double u, double centerX, double centerY, double theta)

        {

            double txx = tx(centerX, theta);

            double tyy = ty(centerY, theta);

            double cost = Math.Cos(theta);

            double sint = Math.Sin(theta);

            double costutxx = cost * (u + txx);

            double sintutyy = sint * (u + tyy);

            return costutxx + sintutyy;

        }

​

        private static double v_star(double u, double centerX, double centerY, double theta)

        {

            return (-1) * Math.Sin(theta) * (u + tx(centerX, theta)) + Math.Cos(theta) * (u + ty(centerY, theta));

        }

​

        public static double ApplyFilterOnOneCoord(double u, double v, double Dh, double Dv, double CenterX, double CenterY, double Theta, int N)

        {

            double u_star = KassWitkin.u_star(u, CenterX, CenterY, Theta);

            double v_star = KassWitkin.v_star(u, CenterX, CenterY, Theta);

            double uStarDh = (u_star / Dh);

            double vStarDh = (v_star / Dv);

            double sqrts = Math.Sqrt(uStarDh + vStarDh);

            double power = Math.Pow(sqrts, 2 * N);

            double divvy = (1 + 0.414 * power);

            double returns = 1 / divvy;

            return returns;

        }

    }

​

    public class KassWitkinBandpassFilter

    {

        public readonly int N = 4;

        public double Dh

        {

            get;

            set;

        }

​

        public double Dv

        {

            get;

            set;

        }

​

        public double CenterX

        {

            get;

            set;

        }

​

        public double CenterY

        {

            get;

            set;

        }

​

        public double Theta

        {

            get;

            set;

        }

​

        ///http://stackoverflow.com/questions/37769350/how-can-i-create-a-bank-of-oriented-band-pass-filters

        private double[, ] GetKernel(int width, int height)

        {

            double[, ] kernel2d = new double[width, height];

            for (int i = 0; i < width; i++)

            {

                for (int j = 0; j < height; j++)

                {

                    kernel2d[i, j] = (double)KassWitkin.ApplyFilterOnOneCoord(i, j, Dh, Dv, CenterX, CenterY, Theta, N);

                }

            }

​

            return kernel2d;

        }

​

        public Complex[, ] ApplyFilter(Complex[, ] input)

        {

            int width = input.GetLength(0);

            int height = input.GetLength(1);

            double[, ] kernel = GetKernel(width, height);

            Complex[, ] output = new Complex[width, height];

            for (int i = 0; i < width; i++)

            {

                for (int j = 0; j < height; j++)

                {

                    output[i, j] = input[i, j] * kernel[i, j];

                }

            }

​

            return output;

        }

    }

}