             validate-indexed-color unimplemented-color-type
         ] }
         { greyscale-alpha [
-            validate-greyscale-alpha raw-bytes LA
+            validate-greyscale-alpha decode-greyscale-alpha LA
         ] }
         { truecolor-alpha [
             validate-truecolor-alpha raw-bytes RGBA

: validate-truecolor-alpha ( loading-png -- loading-png )
    { 8 16 } validate-bit-depth ;

: loading-png>bitmap ( loading-png -- bytes component-order )
    dup color-type>> {
        { greyscale [

    } case ;

: scale-greyscale ( byte-array loading-png -- byte-array' )
    bit-depth>> {
        { 8 [ ] }
        { 16 [ 2 group [ swap ] assoc-map B{ } concat-as ] }
        [ scale-factor '[ _ * ] B{ } map-as ]
    } case ;

: decode-greyscale ( loading-png -- byte-array )
    [ raw-bytes ] keep scale-greyscale ;
