C code for sharpening filter

/* Sharp Filter */

#include<stdio.h>
#include<conio.h>
#include<string.h>
#include<graphics.h>
#include<math.h>


void sharpen();
void rgb2gray();

typedef struct bmp_header {
unsigned char ft[2];
unsigned long fsz;
unsigned int res1, res2;
unsigned long ofb, sz, wd, ht;
unsigned int npi, bpp;
unsigned long cps, isz, xres, yres;
unsigned long clru, clrimp;
 }TH;
TH *ihdr;
int length, width, temp;
unsigned char ch;
unsigned char pixel[200][250];
char file_name[14];
int i, j,k;
int w[3][3]={{0,-1,0},
    {-1,5,1},
    {0,-1,0}};

void main()
{
int n,m;
long int i,j;
FILE *imgf;
clrscr();
printf("\n\t SPATIAL FILTERING-SHARPNING FILTER\n");
printf("\nEnter the name of the file:-");
scanf("%s",file_name);
fflush(stdin);
imgf=fopen(file_name,"rb");
if(imgf==NULL)
{
printf("\n\a Error");
getch();
exit(0);
}
fread(ihdr, sizeof(TH), 1, imgf);
length=ihdr-> ht;
width=ihdr->wd;
for(i=0; i<length; i++)
for(j=0;j<width; j++)
{
temp=0;
for(k=0;k<3;k++)
{
ch=fgetc(imgf);
temp=temp+ch;
}
temp=temp/3;
pixel[i][j]=temp;
}
fclose(imgf);
rgb2gray();
sharpen();
       // printf("\n\n To observe the gray scale image open SPATIAL1.bmp:");
printf("\n\n To observe the output image open SHARP.bmp");
getch();
}


void rgb2gray()
{
FILE *imgf1;
imgf1=fopen("spatial1.bmp"," wb");
fwrite(ihdr, sizeof(TH), 1, imgf1);
for(i=0; i< length; i++)
for(j=0; j<width; j++)
{
for(k=0; k<3;k++)
{
fputc(pixel[i][j], imgf1);
}
}
fclose(imgf1);
}

void sharpen()
{
FILE *imgf;
float temp1;
imgf=fopen("sharp.bmp","wb");
fwrite(ihdr, sizeof(TH),1, imgf);
for(i=0; i< length; i++)
for(j=0; j<width; j++)
{
if(i==0||j==0||i==(length-1)||j==(width-1))
{
temp=pixel[i][j];
fputc((int)temp,imgf);
fputc((int)temp,imgf);
fputc((int)temp,imgf);
}
else
{
temp=(((int)(pixel[i-1][j+1])*(w[0][2])) + ((int)(pixel[i-1][j-1]) * (w[0][0])) + ((int)(pixel[i-1][j]) * (w[0][1])) +((int)(pixel[i][j-1]) * (w[1][0])) + ((int)(pixel[i][j]) * (w[1][1]))+((int)(pixel[i][j+1]) * (w[1][2])) +((int)(pixel[i+1][j-1]) * (w[2][0])) +((int)(pixel[i+1][j]) * (w[2][1]))+((int)(pixel[i+1][j+1]) * (w[2][2])));
if(temp==0)
temp=pixel[i][j];
if(temp>=255)
temp=255;
fputc((int)temp,imgf);
fputc((int)temp,imgf);
fputc((int)temp,imgf);
}
}
fclose(imgf);
}