사용한 라이브러리

Q.16. Prewitt 필터

int main()
{
    PPM ppm("imori.pnm");
    int width = ppm.Get_width();
    int height = ppm.Get_height();
    PPM ppm2(width, height);

    auto kernel = [&](int i, int j)
    {
        double ret = 0;
        /*if (j == -1)
        {
            if (i == -1 || i == 1) ret = 1;
            else if (i == 0) ret = 1;
        }
        else if (j == 1)
        {
            if (i == -1 || i == 1) ret = -1;
            else if (i == 0) ret = -1;
        }*/
        if (i == -1)
        {
            if (j == -1 || j == 1) ret = 1;
            else if (j == 0) ret = 1;
        }
        else if (i == 1)
        {
            if (j == -1 || j == 1) ret = -1;
            else if (j == 0) ret = -1;
        }


        return ret;// / 16.;
    };

    auto conv = [&](const std::vector<std::vector<double>>& f)
    {
        std::vector < std::vector < double >> ret(width, std::vector<double>(height));
        for (int j = 0; j < height; j++)
            for (int i = 0; i < width; i++)
            {
                ret[i][j] = 0;
            }
        for (int j = 0; j < height; j++)
            for (int i = 0; i < width; i++)
            {
                int sum = 0;
                for (int di = -1; di <= 1; di++)
                    for (int dj = -1; dj <= 1; dj++)
                    {
                        if (i - di >= 0 && i - di < width && j - dj >= 0 && j - di < height)
                        {
                            ret[i][j] += kernel(di, dj) * f[i - di][j - dj];
                            sum += kernel(di, dj);
                        }
                    }
                //ret[i][j] /= (double)sum;
            }
        return ret;
    };

    std::vector < std::vector < double >> arry(width, std::vector<double>(height));
    for (int j = 0; j < height; j++)
        for (int i = 0; i < width; i++)
        {
            int r = ppm(i, j, 'r');
            int g = ppm(i, j, 'g');
            int b = ppm(i, j, 'b');
            int y = (std::round)(0.2126 * r + 0.7152 * g + 0.0722 * b);
            arry[i][j] = y;
        }
    arry = conv(arry);

    for (int j = 0; j < height; j++)
        for (int i = 0; i < width; i++)
        {
            int val = abs(arry[i][j]);
            if (val > 255) val = 255;
            ppm2(i, j, 'r') = val;
            ppm2(i, j, 'g') = val;
            ppm2(i, j, 'b') = val;

        }

    ppm2.Flush("out.ppm");
    return 0;
}