diff --git a/tools/fimgfx.c b/tools/fimgfx.c
index 08d29023..360843e8 100644
--- a/tools/fimgfx.c
+++ b/tools/fimgfx.c
@@ -19,7 +19,8 @@ typedef struct {
 	int		nbarg;
 	} Fx;
 
-enum fxid { Fx_cos01, Fx_cos010, Fx_pow2, Fx_sqrt, Fx_gray0, Fx_halfsz0 };
+enum fxid { Fx_cos01=5, Fx_cos010, Fx_pow2, Fx_sqrt, Fx_gray0, Fx_halfsz0,
+		Fx_xper };
 
 Fx fx_list[] = {
 	{ "cos01",		Fx_cos01,	0 },
@@ -28,6 +29,7 @@ Fx fx_list[] = {
 	{ "sqrt",		Fx_sqrt,	0 },
 	{ "gray0",		Fx_gray0,	0 },
 	{ "halfsz0",		Fx_halfsz0,	0 },
+	{ "xper",		Fx_xper,	0 },
 	{ NULL,			0,	0 }
 	};
 
@@ -42,15 +44,39 @@ fprintf(stderr, ">>> %s ( '%s' )\n", __func__, txt);
 #endif
 
 for (n=0, fx=fx_list; fx->name; fx++, n++) {
-#if DEBUG_LEVEL
+#if DEBUG_LEVEL > 1
 	fprintf(stderr, "-> %3d %s\n", n, fx->name);
 #endif
 	if (!strcmp(fx->name, txt)) {
 		return n;
 		}
 	}
+return -1;		/* NOT FOUND */
+}
+/* --------------------------------------------------------------------- */
+int do_experiment(FloatImg *S, FloatImg *D, float kf)
+{
+int		foo;
 
-return -1;
+#if DEBUG_LEVEL
+fprintf(stderr, ">>> %s ( %p %p %f )\n", __func__, S, D, kf);
+#endif
+
+foo = fimg_copy_data(S, D);
+if (foo) {
+	fprintf(stderr, "%s err %d copy data %p -> %p\n", __func__,
+				foo, 		S, D);
+	return -98;
+	}
+
+foo = fimg_killcolors_a(D, kf);
+if (foo) {
+	fprintf(stderr, "%s err %d killcolors %p %f\n", __func__,
+				foo, 		S, kf);
+	return -98;
+	}
+
+return 0;
 }
 /* --------------------------------------------------------------------- */
 static void help(int lvl)
@@ -113,6 +139,10 @@ switch (act) {
 		fimg_to_gray(&src); fimg_copy_data(&src, &dest);
 								break;
 
+	case Fx_xper:
+		do_experiment(&src, &dest, maxval);		break;
+		
+
 	case Fx_halfsz0:
 		fprintf(stderr, "not implemented\n");
 		return -3;