+ auto shift to zero

funcs/saturation.c

@@ -70,5 +70,30 @@ for (idx=0; idx<sz; idx++) {
 return 0;
 }
 
-
 /* -------------------------------------------------------------- */
+int  fimg_auto_shift_to_zero(FloatImg *src, FloatImg *dst)
+{
+float		coefs[6];
+int		foo;
+
+if (FIMG_TYPE_RGB != src->type) {
+	fprintf(stderr, "%s: bad image type %d\n", __func__, src->type);
+	return -6;
+	}
+
+foo = fimg_get_minmax_rgb(src, coefs);
+if (foo) {
+	fprintf(stderr, "%s: err %d get minmax\n", __func__, foo);
+	return foo;
+	}
+
+foo = fimg_shift_to_zero(src, dst, coefs);
+if (foo) {
+	fprintf(stderr, "%s WTF?\n", __func__);
+	return foo;
+	}
+
+return 0;
+}
+/* -------------------------------------------------------------- */
+