/* GrayPower.cpp
*
*   Generate 256 level 8 x 1 grayscale
*/
#include <stdio.h>
#include <math.h>
#include "image.h"

void GrayPower(IMAGE *out, double expon);

const int LEVELS = 8;
const int CELL_SIZE = 512 / LEVELS;

int main(int argc, char *argv[])
{
	IMAGE *ip;
	char *filename;
	double expon;

	filename = "gray.img";
	expon = 2.0;
	if (argc<2) printf("Usage: graypower filename expon\n");
	if (argc>1) filename = argv[1];
	if (argc>2) sscanf(argv[2],"%lf",&expon);
	ip = make_image(filename,LEVELS*CELL_SIZE,CELL_SIZE,PIX_BYTE);
	printf("filename: %s\n",filename);
	printf("image size: %d x %d\n",ip->hlen,ip->vlen);
	printf("power law exponent: %g\n",expon);
	GrayPower(ip, expon);
	return 0;
}

void GrayPower(IMAGE *out, double expon)
{
	int i, j, k;
	pixel *buf, color;
	double dx = 1.0/(LEVELS-1);
	buf = make_buffer(out);
	for (i=k=0; i<LEVELS; i++) {
		color = (long) (255*pow(dx*i,expon));
		for (j=0; j<CELL_SIZE; j++) buf[k++] = color;
	}
	for (j=k=0; j<out->vlen; j++) {
		put_line(out,j,buf,PIX_BYTE);
	}
	free_buffer(buf);
}