pixel是通过标准jdk或android bitmap获取的图像32位像素数组
这个方法的滤波器尺寸是3*3，需要更大尺寸滤波器可以依此类推，ColorModel可根据各平台变化调整

private int[] medianFiltering(int[] pixel, int w, int h) {
        int[] newPixel = new int[w * h];
        int[] tempR = new int[9];
        int[] tempG = new int[9];
        int[] tempB = new int[9];
        ColorModel cm = ColorModel.getRGBdefault();
        // median values of the matrix
        int r;
        int g;
        int b;
        for (int y = 0; y < h; y++) {
            for (int x = 0; x < w; x++) {
                if (x == 0 || x == w - 1 || y == 0 || y == h - 1) {
                    newPixel[y * w + x] = pixel[y * w + x];
                    continue;
                }
                tempR[0] = cm.getRed(pixel[x - 1 + (y - 1) * w]);
                tempR[1] = cm.getRed(pixel[x + (y - 1) * w]);
                tempR[2] = cm.getRed(pixel[x + 1 + (y - 1) * w]);
                tempR[3] = cm.getRed(pixel[x - 1 + y * w]);
                tempR[4] = cm.getRed(pixel[x + y * w]);
                tempR[5] = cm.getRed(pixel[x + 1 + y * w]);
                tempR[6] = cm.getRed(pixel[x - 1 + (y + 1) * w]);
                tempR[7] = cm.getRed(pixel[x + (y + 1) * w]);
                tempR[8] = cm.getRed(pixel[x + 1 + (y + 1) * w]);
                r = getMedianValue(tempR);

                tempG[0] = cm.getGreen(pixel[x - 1 + (y - 1) * w]);
                tempG[1] = cm.getGreen(pixel[x + (y - 1) * w]);
                tempG[2] = cm.getGreen(pixel[x + 1 + (y - 1) * w]);
                tempG[3] = cm.getGreen(pixel[x - 1 + y * w]);
                tempG[4] = cm.getGreen(pixel[x + y * w]);
                tempG[5] = cm.getGreen(pixel[x + 1 + y * w]);
                tempG[6] = cm.getGreen(pixel[x - 1 + (y + 1) * w]);
                tempG[7] = cm.getGreen(pixel[x + (y + 1) * w]);
                tempG[8] = cm.getGreen(pixel[x + 1 + (y + 1) * w]);

                g = getMedianValue(tempG);
                tempB[0] = cm.getBlue(pixel[x - 1 + (y - 1) * w]);
                tempB[1] = cm.getBlue(pixel[x + (y - 1) * w]);
                tempB[2] = cm.getBlue(pixel[x + 1 + (y - 1) * w]);
                tempB[3] = cm.getBlue(pixel[x - 1 + y * w]);
                tempB[4] = cm.getBlue(pixel[x + y * w]);
                tempB[5] = cm.getBlue(pixel[x + 1 + y * w]);
                tempB[6] = cm.getBlue(pixel[x - 1 + (y + 1) * w]);
                tempB[7] = cm.getBlue(pixel[x + (y + 1) * w]);
                tempB[8] = cm.getBlue(pixel[x + 1 + (y + 1) * w]);

                // median value
                b = getMedianValue(tempB);
                newPixel[y * w + x] = 255 << 24 | r << 16 | g << 8 | b;
            }
        }
        return newPixel;
    }