CCS: fwrite not working as required.

#include <stdio.h>
#include <stdlib.h>
#define WIDTH   640
#define HEIGHT  480


void main()
{

    
	int size,x,y,value;

	unsigned int *data[2];

	FILE   *Fp_input;
	FILE   *Fp_output;
	unsigned char buffer1[WIDTH];
	unsigned char buffer2[WIDTH];

	unsigned char *ptr1, *ptr2, *inptr1, *inptr2, *inptr3, *temp;
	unsigned int WordWidth = sizeof(unsigned int);

    

	data[0] = (unsigned int*)malloc(WIDTH*HEIGHT);
	data[1] = (unsigned int*)malloc((WIDTH*HEIGHT)/2);
	ptr1 = buffer1;
	ptr2 = buffer2;

	Fp_output = fopen("output.y","wb");
    if ( Fp_output == 0 )
    {
            printf("couldn't write output file");
            exit(EXIT_FAILURE);
    }
    
	
	Fp_input = fopen("VGA.y","rb");
	
	if ( Fp_input == 0 )
	{
        	printf("couldn't open input file");
        	exit(EXIT_FAILURE);
	}
	else 
	{

	//while(!feof(Fp_input))
	{
		size = fread( data[0], WordWidth, (WIDTH*HEIGHT)/(WordWidth), Fp_input );
		//size = fread( data[1], WordWidth, (WIDTH*HEIGHT)/(2*WordWidth), Fp_input );

		inptr1 = data[0] ;
		inptr2 = inptr1+WIDTH ;
		inptr3 = inptr2+WIDTH ;
		memcpy(ptr1 , inptr1 , WIDTH);
		for ( y = 1; y < HEIGHT; ++y) 
		{
			
                for ( x = 1; x < WIDTH; ++x)
                {
                    value = *(inptr1+(x-1))*(-2)   +   *(inptr1+(x))*(-1)  +  *(inptr1+(x+1))*(-2) +
                        *(inptr2+(x-1))*(0)   +   *(inptr2+(x))*(0)  +  *(inptr2+(x+1))*(0)  +
                        *(inptr3+(x-1))*(2)   +   *(inptr3+(x))*(1)  +  *(inptr3+(x+1))*(2) ;
                    if (value< 0)
                        value =0;
                    if (value>255)
                        value =255;
                    *(ptr2+x) = value;
                }
        memcpy(inptr1 , ptr1 ,WIDTH);
        temp = ptr1;
        ptr1 = ptr2;
        ptr2= temp;
        inptr1 += WIDTH;
        inptr2 += WIDTH;
        inptr3 += WIDTH;
	}

		fwrite( data[0], WordWidth,   (WIDTH*HEIGHT)/WordWidth, Fp_output );
   }

  }

}