diff --git a/floatimg.h b/floatimg.h
index d4b91e4f..272c0593 100644
--- a/floatimg.h
+++ b/floatimg.h
@@ -2,7 +2,7 @@
  *	floatimg.h
  */
 
-#define		FIMG_VERSION	87
+#define		FIMG_VERSION	88
 
 /*
  *	in memory descriptor
@@ -57,7 +57,6 @@ int   fimg_print_version(int k);
 void  fimg_printhead(FloatImg *h);
 int   fimg_describe(FloatImg *head, char *txt);
 char *fimg_str_type(int type);
-int   fimg_fileinfo(char *fname, int *datas);
 int   fimg_plot_rgb (FloatImg *head, int x, int y, float r, float g, float b);
 int   fimg_clear(FloatImg *fimg);
 int   fimg_add_rgb(FloatImg *head, int x, int y, float r, float g, float b);
@@ -91,6 +90,7 @@ int fimg_cos_01(FloatImg *s, FloatImg *d, double maxval);
 int fimg_cos_010(FloatImg *s, FloatImg *d, double maxval);
 
 int fimg_mk_gray_from(FloatImg *src, FloatImg*dst, int k);
+int fimg_desaturate(FloatImg *src, FloatImg *dst, int k);
 
 /*	module funcs/rampes.c		*/
 int fimg_hdeg_a(FloatImg *img, double dcoef);
diff --git a/lib/fimg-2gray.c b/lib/fimg-2gray.c
index 70723bbf..52a774d8 100644
--- a/lib/fimg-2gray.c
+++ b/lib/fimg-2gray.c
@@ -52,6 +52,28 @@ for (foo=0; foo<nbb; foo++) {
 return 0;
 }
 /* --------------------------------------------------------------------- */
+int fimg_desaturate(FloatImg *src, FloatImg *dst, int k)
+{
+int		foo, nbb;
+float		fval;
+
+/* we must check the validity of our parameters */
+if (FIMG_TYPE_RGB != src->type || FIMG_TYPE_RGB != dst->type) {
+	fprintf(stderr, "%s : bad image type\n", __func__, src->type, src);
+	return -18;
+	}
+
+/* entering the main processing loop */
+nbb = src->width * src->height;
+
+for (foo=0; foo<nbb; foo++) {
+	dst->R[foo] = dst->G[foo] = dst->B[foo] =
+			(src->R[foo] + src->G[foo] + src->B[foo]) / 3.0;
+	}
+
+return -99;
+}
+/* --------------------------------------------------------------------- */