diff --git a/lib/interpolate.c b/lib/interpolate.c
index ac813abb..03411f16 100644
--- a/lib/interpolate.c
+++ b/lib/interpolate.c
@@ -10,6 +10,12 @@
 int		verbosity;
 
 /* ---------------------------------------------------------------- */
+static int gray_interpolate(FloatImg *s1, FloatImg *s2, FloatImg *d, float coef)
+{
+return -1;
+}
+/* ---------------------------------------------------------------- */
+
 int fimg_interpolate(FloatImg *s1, FloatImg *s2, FloatImg *d, float coef)
 {
 int		picsize, idx;
@@ -31,7 +37,7 @@ if (FIMG_TYPE_RGB != d->type) {
         return -9;
         }
 
-picsize = d->width * d->height * 2;
+picsize = d->width * d->height * 3;
 
 for (idx=0; idx<picsize; idx++) {
 
@@ -39,6 +45,6 @@ for (idx=0; idx<picsize; idx++) {
 
 	}
 
-return -1;
+return 0;
 }
 /* ---------------------------------------------------------------- */