Edges

void edges(int height, int width, RGBTRIPLE image[height][width])
{
    RGBTRIPLE copy[height][width];
    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            copy[i][j] = image[i][j];
        }
    }

    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            image[i][j].rgbtRed = color_value('r', i, j, height, width, copy);
            image[i][j].rgbtGreen = color_value('g', i, j, height, width, copy);
            image[i][j].rgbtBlue = color_value('b', i, j, height, width, copy);
        }
    }
    return;
}

int color_value(char color, int i, int j, int height, int width, RGBTRIPLE pixels[height][width])
{
    //Arrays for Gx and Gy for weighted sum
    int Gx[] = {-1, 0, 1, -2, 0, 2, -1, 0, 1};
    int Gy[] = {-1, -2, -1, 0, 0, 0, 1, 2, 1};
    int Gx_value = 0;
    int Gy_value = 0;

    for (int k = 0; k < 9; k++)
    {
        int box_height = i + (k % 3) - 1; // "-1" is offset from pixel
        int box_width = j + (k / 3) - 1;
        // Check if pixel is out of border
        if (box_height < 0 || box_width < 0 || box_height >= height || box_width >= width)
        {
            Gx_value += 0;
            Gy_value += 0;
            continue;
        }
        switch(color)
        {
            case 'r':
            Gx_value += Gx[k] * pixels[box_height][box_width].rgbtRed;
            Gy_value += Gy[k] * pixels[box_height][box_width].rgbtRed;
            break;
            case 'g':
            Gx_value += Gx[k] * pixels[box_height][box_width].rgbtGreen;
            Gy_value += Gy[k] * pixels[box_height][box_width].rgbtGreen;
            break;
            case 'b':
            Gx_value += Gx[k] * pixels[box_height][box_width].rgbtBlue;
            Gy_value += Gy[k] * pixels[box_height][box_width].rgbtBlue;
            break;
        }
    }
    return (round(sqrt(Gx_value * Gx_value + Gy_value * Gy_value)) < 256) ? round(sqrt(Gx_value * Gx_value + Gy_value * Gy_value)) : 255;
}