diff --git a/floatimg.h b/floatimg.h
index c9e40d04..ebf8cea2 100644
--- a/floatimg.h
+++ b/floatimg.h
@@ -2,7 +2,7 @@
  *	floatimg.h
  */
 
-#define		FIMG_VERSION	94
+#define		FIMG_VERSION	95
 
 /*
  *	in memory descriptor
@@ -80,8 +80,17 @@ int fimg_minimum(FloatImg *a, FloatImg *b, FloatImg *d);
 int fimg_maximum(FloatImg *a, FloatImg *b, FloatImg *d);
 
 
+/*	funcs/filtrage.c		*/
+
+typedef struct {
+	float		matrix[9];
+	float		mult;
+	float		offset;
+	} FimgFilter3x3;
+
 int fimg_killborders(FloatImg *img);
 int fimg_lissage_2x2(FloatImg *img);
+int fimg_filter_3x3(FloatImg *s, FloatImg *d, FimgFilter3x3 *filtr);
 
 /*	'sfx0' module 			*/
 int fimg_killcolors_a(FloatImg *fimg, float fval);
@@ -127,6 +136,7 @@ void  fimg_mul_cste(FloatImg *fi, float value);
 int   fimg_normalize(FloatImg *fi, double maxima, int notused);
 void  fimg_drand48(FloatImg *fi, float kmul);
 int   fimg_count_negativ(FloatImg *fi);
+int   fimg_clamp_negativ(FloatImg *fi);
 
 /*	various funcs modules		*/
 int   fimg_load_from_png(char *filename, FloatImg *fimg);
diff --git a/lib/fimg-math.c b/lib/fimg-math.c
index 9fef44b0..bfcd23ea 100644
--- a/lib/fimg-math.c
+++ b/lib/fimg-math.c
@@ -144,6 +144,31 @@ for (idx=0; idx<nbre; idx++) {
 	if (fi->R[idx] < 0.0) count++;
 	}
 
+return count;
+}
+/* ---------------------------------------------------------------- */
+/* nouveau 29 fevrier 2020 */
+int fimg_clamp_negativ(FloatImg *fi)
+{
+int		nbre, idx;
+int		count;
+
+if (fi->type != FIMG_TYPE_RGB) {
+	fprintf(stderr, "%s : type %d invalide\n",
+				__func__, fi->type);
+	return -1;
+	}
+
+nbre = fi->width * fi->height * fi->type;
+
+count = 0;
+for (idx=0; idx<nbre; idx++) {
+	if (fi->R[idx] < 0.0) {
+		fi->R[idx] = 0.0;
+		count++;
+		}
+	}
+
 return count;
 }
 /* ---------------------------------------------------------------- */