/******************************************************************************** This program was developed by David Pitts on July 27, 1995 based upon a       * program written by Jiawen Yang (which converts viff format to pic format).    

* This program reads a TARGA format, allows the student to perform processing   * and outputs a targa format which can be displayed on the Sun Solaris system */

# include "stdio.h"

/*************************************/
/*         Function Prototypes       */
/*************************************/
void Open_io(void);
void Read_write_hdr(void);
void Pause(void);
void Read_pixels(void);
void Modify_image(void);
void Write_pixels(void);


/*************************************/
/*          Globals                  */
/*************************************/


FILE *fpin,*fpout;
int gpicval[512][512],gnew[512][512],gmaxx,gmaxy;
unsigned char gdata_char;

int main(void)	/* read in a B & W targa file, allows processing, and */
		/* writes out a targa file of the same size as input  */
		/* max size of targa file is 512 lines by 512 pixels */
                /* The user should change the "Modify_image" function in */
                /* order to perform image processing functions       */
{

Open_io ();               /* open an input and an output file */
Read_write_hdr();
Pause();
Read_pixels();

Modify_image();

Write_pixels();
}                         /* end of main program */

/* _______________________________________________________________ */


void Open_io(void)                 /* open an input file and an output file */
{
	fpin=fopen("lenna.tga","rb");     /* name of input targa file */
	if (fpin == NULL)
		{
		printf("cannot open input file\n");
		exit(0);
		}
	fpout=fopen("new.tga","wb");   /* name of output targa file */
	if (fpout == NULL)
		{
		printf("cannot open output file\n");
		exit(1);
		}
}

/* _______________________________________________________________ */

void Read_write_hdr(void)
{
int j,hdr[18];
	for (j=0;j<18;j++)
		{
		fscanf(fpin,"%c",&gdata_char);       /* read input hdr */
		fprintf(fpout,"%c",gdata_char);      /* write output hdr */

		hdr[j]=gdata_char;                /* convert to integer */
                                                 /* for subsequent access */
                                                 /* by image proc. routines */

		printf("Location=%d,Value=%d\n",j,hdr[j]);
		}
printf("\ncompleted reading and writing the 18 bytes header\n");

gmaxy=256*hdr[15]+hdr[14]; /* number of lines in image */
printf("\nNumber of lines in the image = %d\n",gmaxy);   /*  k & y  */

gmaxx=256*hdr[13]+hdr[12]; /* number of pixels per line */
printf("\nNumber of pixels per line =%d\n",gmaxx);       /*  j & x  */

if (hdr[16] != 8)
        {
        printf("This image file does not have 8 bits per pixel, exeuction halted\n");
        exit(2);
        }
if (gmaxx > 512 || gmaxy > 512)
        {
        printf("Image size greater than 512, execution halted\n");
        exit(3);
        }

}

/* _______________________________________________________________ */

void Pause(void)                   /* wait for carriage return to continue */
{
int k,j;
	printf("\n");
	printf("Press return to continue\n");
	scanf("%c",&gdata_char);
}
/* _______________________________________________________________ */

void Read_pixels(void)
{
int k,j;
	for (k=0;k<gmaxy;k++)
	{
	for (j=0;j<gmaxx;j++)

		{
		fscanf(fpin,"%c",&gdata_char);
		gpicval[j][k]=gdata_char;
		gnew[j][k]=gdata_char;
		}
	printf("Line = %d\n",k);
	}
}

/* _______________________________________________________________ */


void Write_pixels(void)
{
int k,j;
	for (k=0;k<gmaxy;k++)
	for (j=0;j<gmaxx;j++)
		{
		gdata_char=gnew[j][k];
		fprintf(fpout,"%c",gdata_char);
		}
	fclose(fpin);
	fclose(fpout);
}

/* _______________________________________________________________ */


void Modify_image(void)
{
/* put whatever routine you wish here to change gnew[j][k]     */
/* into whatever form you wish using the data from            */
/* the original image: gpicvalj][k]  For example:             */
/* dividing by 2 will make the image darker i.e. reduce both  */
/* the gain and contrast                                      */
int k,j;

	for (k=0;k<gmaxy;k++)
	for (j=0;j<gmaxx;j++)
		{
		gnew[j][k]= gpicval[j][k]/2;
		}
}