EdgeDetectHorizontal

// CSharpFilters.BitmapFilter
public unsafe static bool EdgeDetectHorizontal(Bitmap b)
{
    Bitmap bitmap = (Bitmap)b.Clone();
    BitmapData bitmapData = b.LockBits(new Rectangle(0, 0, b.get_Width(), b.get_Height()), 3, 137224);
    BitmapData bitmapData2 = bitmap.LockBits(new Rectangle(0, 0, b.get_Width(), b.get_Height()), 3, 137224);
    int stride = bitmapData.get_Stride();
    IntPtr scan = bitmapData.get_Scan0();
    IntPtr scan2 = bitmapData2.get_Scan0();
    byte* ptr = (byte*)((void*)scan);
    byte* ptr2 = (byte*)((void*)scan2);
    int num = stride - b.get_Width() * 3;
    int num2 = b.get_Width() * 3;
    ptr += stride;
    ptr2 += stride;
    for (int i = 1; i < b.get_Height() - 1; i++)
    {
        ptr += 9;
        ptr2 += 9;
        for (int j = 9; j < num2 - 9; j++)
        {
            int num3 = (int)((ptr2 + stride - 9)[0] + (ptr2 + stride - 6)[0] + (ptr2 + stride - 3)[0] + (ptr2 + stride)[0] + (ptr2 + stride + 3)[0] + (ptr2 + stride + 6)[0] + (ptr2 + stride + 9)[0] - (ptr2 - stride - 9)[0] - (ptr2 - stride - 6)[0] - (ptr2 - stride - 3)[0] - (ptr2 - stride)[0] - (ptr2 - stride + 3)[0] - (ptr2 - stride + 6)[0] - (ptr2 - stride + 9)[0]);
            if (num3 < 0)
            {
                num3 = 0;
            }
            if (num3 > 255)
            {
                num3 = 255;
            }
            (ptr + stride)[0] = (byte)num3;
            ptr++;
            ptr2++;
        }
        ptr += 9 + num;
        ptr2 += 9 + num;
    }
    b.UnlockBits(bitmapData);
    bitmap.UnlockBits(bitmapData2);
    return true;
}