diff --git a/floatimg.h b/floatimg.h
index dbf633d..8f5775b 100644
--- a/floatimg.h
+++ b/floatimg.h
@@ -20,7 +20,7 @@
  *	https://git.tetalab.org/tTh/FloatImg
  */
 
-#define		FIMG_VERSION	(231)
+#define		FIMG_VERSION	(234)
 #define		RELEASE_NAME	("noname")
 #define		PATCH_LEVEL	("aaaa")
 
@@ -32,8 +32,7 @@
 /*
  *		new 11 mars 2022, and a lot of iterations
  *		around the concept of metadata for my work.
- */
-/*
+ *
  *	we MUST look at packing and endianess problems NOW
  *	and we can think about a fixed size of this datablock
  */
@@ -232,6 +231,7 @@ int fimg_falsecolors_0(FloatImg *src, FloatImg *dst, int k, float valf);
 /*	funcs/fmorpho.c			*/
 int fimg_filtre_morpho_0(FloatImg *sfimg, FloatImg *dfimg, int index);
 
+int fimg_auto_thermique(FloatImg *src, FloatImg *dst, int k);
 
 /*	--> funcs/plasmas.c		*/
 int fimg_prototype_plasma(FloatImg *img, double time, int type);
diff --git a/funcs/tests.c b/funcs/tests.c
index 2bffb67..2797abd 100644
--- a/funcs/tests.c
+++ b/funcs/tests.c
@@ -1192,7 +1192,7 @@ memset(&dst, 0, sizeof(FloatImg));
 foo = fimg_clone(&src, &dst, 0);
 if (foo) return -888;
 
-fimg_auto_thermique(&src, &dst, 0);
+foo = fimg_auto_thermique(&src, &dst, 0);
 
 foo = fimg_export_picture(&dst, outfile, 0);
 if (foo) {
diff --git a/funcs/thermocolor.c b/funcs/thermocolor.c
index b924c45..ab0e59b 100644
--- a/funcs/thermocolor.c
+++ b/funcs/thermocolor.c
@@ -15,7 +15,9 @@
 extern int		verbosity;
 
 /* --------------------------------------------------------------------- */
-
+/*
+ *	parameter k in not used, but may be in the futur.
+ */
 int fimg_auto_thermique(FloatImg *src, FloatImg *dst, int k)
 {
 // int		x, y, off;
@@ -29,11 +31,11 @@ fprintf(stderr, ">>> %s ( %p  %p  %d )\n", __func__, src, dst, k);
 #endif
 
 if (0!=k) {
-	fprintf(stderr, "%s: k mus be 0, was %d\n", __func__, k);
+	fprintf(stderr, "%s: k must be 0, was %d\n", __func__, k);
 	}
 
 surface = src->width * src->height;
-fprintf(stderr, "surface = %d\n", surface);
+// fprintf(stderr, "surface = %d\n", surface);
 
 graymean = 0.0;
 for (idx=0; idx<surface; idx++) {
@@ -43,6 +45,9 @@ for (idx=0; idx<surface; idx++) {
 seuil = (float) (graymean / surface);
 // fprintf(stderr, "graymean = %f   seuil = %f\n", graymean, seuil);
 
+/*
+ *	please, explain this number brotching
+ */
 for (idx=0; idx<surface; idx++) {
 	gray = src->R[idx] + src->G[idx] + src->B[idx];
 	if (gray > seuil) {