Pset 4 Filter - Blur

Question

My blur filter produces a decent looking blurred image and passes the Check50 corner pixel case.

I define the cases for the edges and the middle pixels and then manually calculate the average RGB values for the pixel.

I appreciate my code is long-winded, but I would really appreciate if someone could give me a hint of where I am going wrong please.

Thanks.

void blur(int height, int width, RGBTRIPLE image[height][width])
{
    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            // Corners
            if (i == 0 && j == 0)
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i + 1][j].rgbtRed + image[i + 1][j + 1].rgbtRed + image[i][j + 1].rgbtRed) / 4.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i + 1][j].rgbtGreen + image[i + 1][j + 1].rgbtGreen + image[i][j + 1].rgbtGreen) / 4.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i + 1][j].rgbtBlue + image[i + 1][j + 1].rgbtBlue + image[i][j + 1].rgbtBlue) / 4.0);
            }

            if (i == 0 && j == width - 1)
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i + 1][j].rgbtRed + image[i + 1][j - 1].rgbtRed + image[i][j - 1].rgbtRed) / 4.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i + 1][j].rgbtGreen + image[i + 1][j - 1].rgbtGreen + image[i][j - 1].rgbtGreen) / 4.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i + 1][j].rgbtBlue + image[i + 1][j - 1].rgbtBlue + image[i][j - 1].rgbtBlue) / 4.0);
            }

            if (i == height - 1 && j == width - 1)
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i - 1][j].rgbtRed + image[i - 1][j - 1].rgbtRed + image[i][j - 1].rgbtRed) / 4.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i - 1][j].rgbtGreen + image[i - 1][j - 1].rgbtGreen + image[i][j - 1].rgbtGreen) / 4.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i - 1][j].rgbtBlue + image[i - 1][j - 1].rgbtBlue + image[i][j - 1].rgbtBlue) / 4.0);
            }

            if (i == height - 1 && j == 0)
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i - 1][j].rgbtRed + image[i - 1][j + 1].rgbtRed + image[i][j + 1].rgbtRed) / 4.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i - 1][j].rgbtGreen + image[i - 1][j + 1].rgbtGreen + image[i][j + 1].rgbtGreen) / 4.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i - 1][j].rgbtBlue + image[i - 1][j + 1].rgbtBlue + image[i][j + 1].rgbtBlue) / 4.0);
            }

            // Edges
            if (j == 0 && (i > 0 && i < height - 1))
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i - 1][j].rgbtRed + image[i - 1][j + 1].rgbtRed + image[i][j + 1].rgbtRed + image[i + 1][j + 1].rgbtRed + image[i + 1][j].rgbtRed) / 6.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i - 1][j].rgbtGreen + image[i - 1][j + 1].rgbtGreen + image[i][j + 1].rgbtGreen + image[i + 1][j + 1].rgbtGreen + image[i + 1][j].rgbtGreen) / 6.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i - 1][j].rgbtBlue + image[i - 1][j + 1].rgbtBlue + image[i][j + 1].rgbtBlue + image[i + 1][j + 1].rgbtBlue + image[i + 1][j].rgbtBlue) / 6.0);
            }

            if (i == 0 && (j > 0 && j < width - 1))
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i][j + 1].rgbtRed + image[i + 1][j + 1].rgbtRed + image[i + 1][j].rgbtRed + image[i + 1][j - 1].rgbtRed + image[i][j - 1].rgbtRed) / 6.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i][j + 1].rgbtGreen + image[i + 1][j + 1].rgbtGreen + image[i + 1][j].rgbtGreen + image[i + 1][j - 1].rgbtGreen + image[i][j - 1].rgbtGreen) / 6.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i][j + 1].rgbtBlue + image[i + 1][j + 1].rgbtBlue + image[i + 1][j].rgbtBlue + image[i + 1][j - 1].rgbtBlue + image[i][j - 1].rgbtBlue) / 6.0);

            }

            if (j == width - 1 && (i > 0 && i < height - 1))
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i - 1][j].rgbtRed + image[i - 1][j - 1].rgbtRed + image[i][j - 1].rgbtRed + image[i + 1][j - 1].rgbtRed + image[i + 1][j].rgbtRed) / 6.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i - 1][j].rgbtGreen + image[i - 1][j - 1].rgbtGreen + image[i][j - 1].rgbtGreen + image[i + 1][j - 1].rgbtGreen + image[i + 1][j].rgbtGreen) / 6.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i - 1][j].rgbtBlue + image[i - 1][j - 1].rgbtBlue + image[i][j - 1].rgbtBlue + image[i + 1][j - 1].rgbtBlue + image[i + 1][j].rgbtBlue) / 6.0);
            }

            if (i == height - 1 && (j > 0 && j < width - 1))
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i][j + 1].rgbtRed + image[i - 1][j + 1].rgbtRed + image[i][j - 1].rgbtRed + image[i - 1][j].rgbtRed + image[i - 1][j - 1].rgbtRed) / 6.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i][j + 1].rgbtGreen + image[i - 1][j + 1].rgbtGreen + image[i][j - 1].rgbtGreen + image[i - 1][j].rgbtGreen + image[i - 1][j - 1].rgbtGreen) / 6.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i][j + 1].rgbtBlue + image[i - 1][j + 1].rgbtBlue + image[i][j - 1].rgbtBlue + image[i - 1][j].rgbtBlue + image[i - 1][j - 1].rgbtBlue) / 6.0);

            }

            // Middle
            if ((i > 0 && i < height - 1) && (j > 0 && j < width - 1))
            {
                image[i][j].rgbtRed = round((image[i][j].rgbtRed + image[i - 1][j - 1].rgbtRed + image[i - 1][j].rgbtRed + image[i - 1][j + 1].rgbtRed + image[i][j - 1].rgbtRed + image[i][j + 1].rgbtRed + image[i + 1][j - 1].rgbtRed + image[i + 1][j].rgbtRed + image[i + 1][j + 1].rgbtRed) / 9.0);
                image[i][j].rgbtGreen = round((image[i][j].rgbtGreen + image[i - 1][j - 1].rgbtGreen + image[i - 1][j].rgbtGreen + image[i - 1][j + 1].rgbtGreen + image[i][j - 1].rgbtGreen + image[i][j + 1].rgbtGreen + image[i + 1][j - 1].rgbtGreen + image[i + 1][j].rgbtGreen + image[i + 1][j + 1].rgbtGreen) / 9.0);
                image[i][j].rgbtBlue = round((image[i][j].rgbtBlue + image[i - 1][j - 1].rgbtBlue + image[i - 1][j].rgbtBlue + image[i - 1][j + 1].rgbtBlue + image[i][j - 1].rgbtBlue + image[i][j + 1].rgbtBlue + image[i + 1][j - 1].rgbtBlue + image[i + 1][j].rgbtBlue + image[i + 1][j + 1].rgbtBlue) / 9.0);
            }

        }
    }

    return;
}

Answer 1

What's up. Think what happens once you change RGB pixel values... The first one will be totally fine (which is why check50 works for the corner pixel). The next pixels, however, will calculate their average based on the changed pixel values. You might wanna create a temp image and transfer the temp image to the real one in the end.