java中的matlab函数imresize

Question

我想在 Java 项目中使用 MATLab 函数 imresize。为此，我搜索了这个函数的源代码或 Java 中的一个等价类。

我想将比例因子为 0.4 的 double[][] 调整为新的 double[][]。

我已经找到了一个 SourceCode，但是这个 Code 使用了一个 Matlab.sum 函数，而我没有：

import java.util.ArrayList;
import java.util.List;

public class MatlabResize {
    private static final double TRIANGLE_KERNEL_WIDTH = 2;

    public static double[][] resizeMatlab(double[][] data, double scale) {
        int out_x = (int)Math.ceil(data[0].length * scale);
        int out_y = (int)Math.ceil(data.length * scale);

        double[][][] weights_indizes = contribution(data.length, out_y, scale, TRIANGLE_KERNEL_WIDTH);
        double[][] weights = weights_indizes[0];
        double[][] indices = weights_indizes[1];

        final double[][] result = new double[out_y][data[0].length];
        double value = 0;

        for (int p=0; p<result[0].length; p++) {
            for (int i=0; i<weights.length; i++) {
                value = 0;

                for (int j=0; j<indices[0].length; j++) {
                    value += weights[i][j] * data[(int)indices[i][j]][p];
                }

                result[i][p] = value;
            }
        }

        weights_indizes = contribution(data[0].length, out_x, scale, TRIANGLE_KERNEL_WIDTH);
        weights = weights_indizes[0];
        indices = weights_indizes[1];

        final double[][] result2 = new double[result.length][out_x];
        for (int p=0; p<result.length; p++) {
            for (int i=0; i<weights.length; i++) {
                value = 0;

                for (int j=0; j<indices[0].length; j++) {
                    value += weights[i][j] * result[p][(int)indices[i][j]];
                }

                result2[p][i] = value;
            }
        }

        return result2;
    }


    private static double[][][] contribution(int length, int output_size, double scale, double kernel_width) {
        if (scale < 1.0) {
            kernel_width = kernel_width/scale;
        }

        final double[] x = new double[output_size];
        for (int i=0; i<x.length; i++) {
            x[i] = i+1;
        }

        final double[] u = new double[output_size];
        for (int i=0; i<u.length; i++) {
            u[i] = x[i]/scale + 0.5*(1 - 1/scale);
        }

        final double[] left = new double[output_size];
        for (int i=0; i<left.length; i++) {
            left[i] = Math.floor(u[i] - kernel_width/2);
        }

        int P = (int)Math.ceil(kernel_width) + 2;

        final double[][] indices = new double[left.length][P];
        for (int i=0; i<left.length; i++) {
            for (int j=0; j<=P-1; j++) {
                indices[i][j] = left[i] + j;
            }
        }

        double[][] weights = new double[u.length][indices[0].length];
        for (int i=0; i<u.length; i++) {
            for (int j=0; j<indices[i].length; j++) {
                weights[i][j] = u[i] - indices[i][j];
            }
        }

        if (scale < 1.0) {
            weights = triangleAntiAliasing(weights, scale);
        } else {
            weights = triangle(weights);
        }

        double[] sum = Matlab.sum(weights, 2);
        for (int i=0; i<weights.length; i++) {
            for (int j=0; j<weights[i].length; j++) {
                weights[i][j] = weights[i][j] / sum[i];
            }
        }

        for (int i=0; i<indices.length; i++) {
            for (int j=0; j<indices[i].length; j++) {
                indices[i][j] = Math.min(Math.max(indices[i][j], 1.0), length);
            }
        }

        sum = Matlab.sum(weights, 1);
        int a = 0;

        final List<Integer> list = new ArrayList<Integer>();
        for (int i=0; i<sum.length; i++) {
            if (sum[i] != 0.0) {
                a++;
                list.add(i);
            }
        }

        final double[][][] result = new double[2][weights.length][a];
        for (int i=0; i<weights.length; i++) {
            for (int j=0; j<list.size(); j++) {
                result[0][i][j] = weights[i][list.get(j)];
            }
        }
        for (int i=0; i<indices.length; i++) {
            for (int j=0; j<list.size(); j++) {
                result[1][i][j] = indices[i][list.get(j)]-1; //java indices start by 0 and not by 1
            }
        }

        return result;
    }

    private static double[][] triangle(final double[][] x) {
        for (int i=0; i<x.length; i++) {
            for (int j=0; j<x[i].length; j++) {
                if (-1.0 <= x[i][j] && x[i][j] < 0.0) {
                    x[i][j] = x[i][j] + 1;
                } else if (0.0 <= x[i][j] &&  x[i][j] < 1.0) {
                    x[i][j] = 1 - x[i][j];
                } else {
                    x[i][j] = 0;
                }
            }
        }

        return x;
    }

    private static double[][] triangleAntiAliasing(final double[][] x, final double scale) {
        for (int i=0; i<x.length; i++) {
            for (int j=0; j<x[i].length; j++) {
                x[i][j] = x[i][j] * scale;
            }
        }

        for (int i=0; i<x.length; i++) {
            for (int j=0; j<x[i].length; j++) {
                if (-1.0 <= x[i][j] && x[i][j] < 0.0) {
                    x[i][j] = x[i][j] + 1;
                } else if (0.0 <= x[i][j] &&  x[i][j] < 1.0) {
                    x[i][j] = 1 - x[i][j];
                } else {
                    x[i][j] = 0;
                }
            }
        }

        for (int i=0; i<x.length; i++) {
            for (int j=0; j<x[i].length; j++) {
                x[i][j] = x[i][j] * scale;
            }
        }

        return x;
    }
}

Answer 1

我的 Sum 函数，现在可以使用：:)

public class Matlab {

    public static double[] sum(double[][] weights, int i) {
        double[] des;

        switch (i) {
        case 1:
            des = new double[weights[0].length];
            for (int k = 0; k < weights[0].length; k++) {

                double sum =0;
                for(int j = 0; j<weights.length;j++){
                    sum +=  weights[j][k];
                }
                des[k]=sum;

            }
            return des;

        case 2:
            des = new double[weights.length];
            for(int j = 0; j<weights.length;j++){
                double sum =0;
                for (int k = 0; k < weights[j].length; k++) {
                    sum +=  weights[j][k];
                }
                des[j]=sum;
            }
            return des;

        return null;
    }

}