FloatImg/funcs/histogram.c

/*
 *		FLOATIMG
 *	calculer un histogramme et l'afficher
 */

#include  <stdio.h>
#include  <stdlib.h>
#include  <string.h>

#include  "../floatimg.h"

extern int		verbosity;

/* --------------------------------------------------------------------- */
int fimg_calcul_histo(FloatImg *src, long *ghist, int sz)
{
float		maxval;
int		x, y, idx;
float		rgb[3], moy;

#if DEBUG_LEVEL
fprintf(stderr, ">>> %s ( %p %p %d )\n", __func__, src, ghist, sz);
#endif

maxval = fimg_get_maxvalue(src);

fprintf(stderr, "maximum is %f\n", maxval);

for (y=0; y<src->height; y++)	{
	for(x=0; x<src->width; x++) {
		fimg_get_rgb(src, x, y, rgb);
		moy = (rgb[0]+rgb[1]+rgb[2]) / 3.0;

		/* ok, here the had math part ... */
		idx = (int)( (moy*sz) / maxval);

		/* sanity check */
		if (idx<0 || idx>=sz) {
			fprintf(stderr, "idx = %d, error\n", idx);
			abort();
			}

		ghist[idx]++;
		}
	}

return -66;
}
/* --------------------------------------------------------------------- */

int fimg_essai_histo(FloatImg *src, char *outpic, int nbslices)
{
long		*histo;
int		foo;
FILE		*pipe;

fprintf(stderr, ">>> %s ( %p '%s' %d )\n", __func__, src, outpic, nbslices);

if (NULL==(histo=calloc(nbslices, sizeof(long)))) {
	fprintf(stderr, "OUT OF MEMORY\n");
	abort();
	}

foo = fimg_calcul_histo(src, histo, nbslices);

// for (foo=0; foo<NSLICES; foo++)	{
//	printf("%7d   %ld\n", foo, histo[foo]);
//	}

pipe = popen("gnuplot", "w");
if (NULL==pipe) {
	fprintf(stderr, "%s: error running gnuplot\n", __func__);
	return -17;
	}
fprintf(pipe, "set term png    size 1024,512\n");
fprintf(pipe, "set grid\n");
fprintf(pipe, "set output \"%s\"\n", outpic);
fprintf(pipe, "plot '/dev/stdin' with lines\n");

for (foo=0; foo<nbslices; foo++)	{
	fprintf(pipe, "%d %ld\n", foo, histo[foo]);
	}

pclose(pipe);		// and not fclose (see man page)

free(histo);

return 0;
}
/* --------------------------------------------------------------------- */