C :: Blurring PPM Image By Averaging Components Of Color Within Certain Reach Of Specific Pixel

I'm trying to blur a ppm image by averaging the components of the color(r, g, b) within a certain reach of a specific pixel. This is a picture and description:

In this diagram, we are trying to compute the color for the pixel in the center (the red element). Its neighbors (within a reach of 4) are all of the green elements. The pixels outside of this 9x9 square are not considered in the blurring calculation for this pixel. To compute the color for the center pixel, average the red, green, and blue components (independently) of every pixel in the 9x9 square (including the pixel itself; the red element in this diagram).

I have some code, but it is not working correctly. The function "computed_color" on line 52 is shown in the next block of code.

Code:
#include <stdlib.h>
#include <stdio.h>
#include "blur_calculations.h"
#define NOT_ENOUGH_ARGS 2
#define MIN_ARGS 3
#define PICTURE_FILE 1
#define REACH_NUMBER 4
#define OUTPUT_FILE "blurred.ppm"
#define PPM_NUMBER "P3"
#define MAX_ROWS 500
#define MAX_COLS 500

void solve(FILE *in_picture, FILE *out_picture, char *argv[]) {

[Code] ....

Here is my code to calculate the average, which I use in my "solve" function:

Code:
#include "blur_calculations.h"
struct color create_color(int r, int g, int b) {
struct color colors;
colors.r = r;
colors.g = g;
colors.b = b;
return colors;

[Code] ....