CS50 pset4 过滤器（不太舒服） - 模糊功能不起作用

Question

I am working on the Filter (less comfortable) problem in CS50 (PSET4) and am stuck on the blur function. I am getting an error on check50 for all checkpoints, however, I am unable to figure out where I am going wrong. Will appreciate if someone can help me on this. Thanks. This is what I've written:

// Blur image
void blur(int height, int width, RGBTRIPLE image[height][width])
{
    RGBTRIPLE sum;
    RGBTRIPLE image_copy[height][width];

    //creating copy of image
    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            image_copy[i][j].rgbtBlue = image[i][j].rgbtBlue;
            image_copy[i][j].rgbtGreen = image[i][j].rgbtGreen;
            image_copy[i][j].rgbtRed = image[i][j].rgbtRed;
        }
    }

    //iterating over each pixel
    for (int i = 0; i < height; i++)
    {
        for (int j = 0; j < width; j++)
        {
            sum.rgbtBlue = 0;
            sum.rgbtGreen = 0;
            sum.rgbtRed = 0;
            int count = 0;
            //setting loops for 3*3 grid
            for (int k = i - 1; k <= i + 1; k++)
            {
                if(k >= 0 && k < height)
                {
                    for (int l = j - 1; l <= j + 1; l++)
                    {
                        if (l >= 0 && l < width)
                        {
                            sum.rgbtBlue = sum.rgbtBlue + image_copy[k][l].rgbtBlue;
                            sum.rgbtGreen = sum.rgbtGreen + image_copy[k][l].rgbtGreen;
                            sum.rgbtRed = sum.rgbtRed + image_copy[k][l].rgbtRed;
                            count++;
                        }
                    }
                }
            }
            // calculating average and updating original image
            image[i][j].rgbtBlue = round (sum.rgbtBlue / count);
            image[i][j].rgbtGreen = round (sum.rgbtGreen / count);
            image[i][j].rgbtRed = round (sum.rgbtRed /count);
        }
    }

   return;
}

Answer 1

sum.rgbtBlue / count is integer division , so it has already been rounded down (truncated) before passing to round() .

Not only that but RGBTRIPLE sum cannot values of 765 (3 * 255).

Sum the pixels into three int or float variables, for example

int blue = 0;    // etc.

//...

image[i][j].rgbtBlue = round ((float)blue / count);   // cast before division