cs50 - pset4 - 模糊

Question

I've been working on pset4 - filter, the blur part for many hours now. I'm trying to run this code, but I don't know why, it creates black images. I tried going over stack and some other websites but couldn't find a solution for my problem. Does anyone see the problem with the code below:

// Blur image
void blur(int height, int width, RGBTRIPLE image[height][width])
{
    RGBTRIPLE temp[height][width];
    int counter;
    int sum_red;
    int sum_green;
    int sum_blue;
    for (int i = 0; i < height; i++)
    {
        counter = 0;
        sum_red = 0;
        sum_green = 0;
        sum_blue = 0;
        for (int j = 0; j < width; j++)
        {
            for (int r = -1; r < 2; r++)
            {
                if (r + i < 0 || r + i > height - 1)
                {
                    continue;
                }
                for (int c = -1; c < 2; c++)
                {
                    if (c + j < 0 || c + j > width - 1)
                    {
                        continue;
                    }
                    sum_red += temp[i + r][c + j].rgbtRed;
                    sum_green += temp[i + r][c + j].rgbtGreen;
                    sum_blue += temp[i + r][c + j].rgbtBlue;
                    counter++;

                }

            }
            image[i][j].rgbtRed = round(sum_red / counter);
            image[i][j].rgbtGreen = round(sum_green / counter);
            image[i][j].rgbtBlue = round(sum_blue / counter);
        }

    }
    return;
}

Thanks

Answer 1

You are working with an uninitialised array. You are supposed to copy the image data to RGBTRIPLE temp[height][width]; as the first step.

memcpy(temp, image, sizeof temp);

A smaller fault is with round(sum_red / counter) which does integer division and truncation before being passed to round() , which then does nothing. I suggest using

float sum_red;
float sum_green;
float sum_blue;

Answer 2

Try to declare counter as a float. sum_red , sum_green and sum_blue could be integers