diff --git a/funcs/histogram.c b/funcs/histogram.c
new file mode 100644
index 0000000..158e392
--- /dev/null
+++ b/funcs/histogram.c
@@ -0,0 +1,76 @@
+/*
+ *		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;
+
+fprintf(stderr, ">>> %s ( %p %p %d )\n", __func__, src, ghist, sz);
+
+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;
+}
+/* --------------------------------------------------------------------- */
+
+#define NSLICES 999
+
+int fimg_essai_histo(FloatImg *src, char *outpic, int k)
+{
+long		histo[NSLICES];
+int		foo;
+FILE		*pipe;
+
+fprintf(stderr, ">>> %s ( %p '%s' %d )\n", __func__, src, outpic, k);
+
+memset(histo, 0, NSLICES*sizeof(long));
+
+foo = fimg_calcul_histo(src, histo, NSLICES);
+
+for (foo=0; foo<NSLICES; foo++)	{
+	printf("%7d   %ld\n", foo, histo[foo]);
+	}
+
+pipe = popen("gnuplot", "w");
+fprintf(pipe, "set term png    size 1000,400\n");
+fprintf(pipe, "set output \"histo.png\"\n");
+fprintf(pipe, "plot 'toto' with lines\n");
+fclose(pipe);
+
+
+return -1;
+}
+/* --------------------------------------------------------------------- */
diff --git a/funcs/t.c b/funcs/t.c
index cd024b0..668d242 100644
--- a/funcs/t.c
+++ b/funcs/t.c
@@ -485,7 +485,7 @@ int main(int argc, char *argv[])
 int		foo, opt;
 char		*filename, *command;
 
-puts("++++++++ test des fonctions +++++++");
+fprintf(stderr, "++++++++ test des fonctions pid=%d\n", getpid());
 
 global_fvalue = 1.0;