diff --git a/funcs/fimg-tiff.c b/funcs/fimg-tiff.c
index 76a509a4..f9b59f3e 100644
--- a/funcs/fimg-tiff.c
+++ b/funcs/fimg-tiff.c
@@ -14,6 +14,8 @@ int essai_ecrire_tiff(FloatImg *src, char *fname)
 
 		/* bon, tout cela semble bien tortueux ! */
 
+	fprintf(stderr, "%s %s to be implemented\n", __FILE__, __func__);
+
 return 0;
 }
 /* --------------------------------------------------------------------- */
diff --git a/lib/operators.c b/lib/operators.c
index cd703d2d..12cdc3a5 100644
--- a/lib/operators.c
+++ b/lib/operators.c
@@ -98,6 +98,32 @@ for (idx=0; idx<nbpixels; idx++) {
 	}
 
 return 0;
+}
+/* ---------------------------------------------------------------- */
+/*
+ * 		B *= A		may be faster than fimg_mul_3 ?
+ */
+int fimg_mul_2(FloatImg *a, FloatImg *b)
+{
+int		idx, nbpixels;
+
+#if DEBUG_LEVEL
+fprintf(stderr, ">>> %s ( %p %p )\n", __func__, a, b);
+#endif
+
+if (3 != a->type || 3 != b->type) {
+	fprintf(stderr, "%s : got a bad type fimg\n", __func__);
+	return -8;
+	}
+
+nbpixels = a->width * a->height;
+
+for (idx=0; idx<nbpixels; idx++) {
+	b->R[idx] *= a->R[idx];
+	b->G[idx] *= a->G[idx];
+	b->B[idx] *= a->B[idx];
+	}
+
 }
 /* ---------------------------------------------------------------- */
 /*