fix byte swapping on greyscale-alpha

diff --git a/basis/images/png/png.factor b/basis/images/png/png.factor
index c41a1956cdbe384756a57154bdef41c97455db27..595bb62ed4d3f1a62326d2d90accaa07fc6ed995 100755 (executable)
--- a/basis/images/png/png.factor
+++ b/basis/images/png/png.factor
@@ -215,7 +215,7 @@ ERROR: invalid-color-type/bit-depth loading-png ;
 
 : decode-greyscale-alpha ( loading-image -- byte-array' )
     [ raw-bytes ] [ bit-depth>> ] bi 16 = [
-        3 group [ first3 swapd 3array ] map B{ } concat-as
+        4 group [ first4 [ swap ] 2dip 4array ] map B{ } concat-as
     ] when ;
 
 : loading-png>bitmap ( loading-png -- bytes component-order )