Infinite For-Loop Kuwahara Filter Java

I'm working on a Kuwahara Filter in java for smoothing images while preserving the edges. My current code won't run due to an infinite for-loop, I'm not sure if it's something with the loop itself or an error with a variable or array.

Here's the code:

private static void Processing(BufferedImage img) {
    int w = img.getWidth(null);
    int h = img.getHeight(null);
    int Size = w*h;
    int[] ApetureMinX = {-(Size / 2), 0, -(Size / 2), 0};
    int[] ApetureMaxX = {0, (Size / 2), 0, (Size / 2)};
    int[] ApetureMinY = {-(Size / 2), -(Size / 2), 0, 0};
    int[] ApetureMaxY = {0, 0, (Size / 2), (Size / 2)};
    for (int x = 0; x < w; x++) {
        for (int y = 0; y < h; y++) {
            int rgb = img.getRGB(x, y);
            int a = (rgb & 0xff000000) >>> 24;
            int r = (rgb & 0x00ff0000) >>> 16;
            int g = (rgb & 0x0000ff00) >>> 8;
            int b = rgb & 0x000000ff;

            //  KUWAHARA
            int[] RValues = {0, 0, 0, 0};
            int[] GValues = {0, 0, 0, 0};
            int[] BValues = {0, 0, 0, 0};
            int[] NumPixels = {0, 0, 0, 0};
            int[] MaxRValue = {0, 0, 0, 0};
            int[] MaxGValue = {0, 0, 0, 0};
            int[] MaxBValue = {0, 0, 0, 0};
            int[] MinRValue = {255, 255, 255, 255};
            int[] MinGValue = {255, 255, 255, 255};
            int[] MinBValue = {255, 255, 255, 255};

            for (int i = 0; i < 4; ++i) {
                for (int x2 = ApetureMinX[i]; x2 < ApetureMaxX[i]; ++x2) {
                    int TempX = x + x2;
                    if (TempX >= 0 && TempX < w) {
                        for (int y2 = ApetureMinY[i]; y2 < ApetureMaxY[i]; ++y2) {
                            int TempY = y + y2;
                            if (TempY >= 0 && TempY < h) {
                                int TempColor = img.getRGB(TempX, TempY);
                                int red = (TempColor & 0x00ff0000) >> 16;
                                int green = (TempColor & 0x0000ff00) >> 8;
                                int blue = TempColor & 0x000000ff;
                                RValues[i] += red;
                                GValues[i] += green;
                                BValues[i] += blue;
                                if (red > MaxRValue[i]) {
                                    MaxRValue[i] = red;
                                } else if (red < MinRValue[i]) {
                                    MinRValue[i] = red;
                                }

                                if (green > MaxGValue[i]) {
                                    MaxGValue[i] = green;
                                } else if (green < MinGValue[i]) {
                                    MinGValue[i] = green;
                                }

                                if (blue > MaxBValue[i]) {
                                    MaxBValue[i] = blue;
                                } else if (blue < MinBValue[i]) {
                                   MinBValue[i] = blue;
                                }
                                NumPixels[i]++;
                            }
                        }
                    }
                }
            }
            int j = 0;
            int MinDifference = 10000;
            for (int i = 0; i < 4; ++i) {
                int CurrentDifference = (MaxRValue[i] - MinRValue[i]) + (MaxGValue[i] - MinGValue[i]) + (MaxBValue[i] - MinBValue[i]);
                if (CurrentDifference < MinDifference && NumPixels[i] > 0) {
                    j = i;
                    MinDifference = CurrentDifference;
                    b = BValues[j] / NumPixels[j];
                    g = GValues[j] / NumPixels[j];
                    r = RValues[j] / NumPixels[j];
                }
            }

            // END KUWAHARA // 
            int RGB = b | (g << 8) | (r << 16) | (a << 24);
            img.setRGB(x, y, RGB);
        }
    }

I've tested each separate loop with a print statement and it prints infinite times, which leads me to believe there is something wrong with a variable / array / math in the code.