minor fixes for resize_png

data_from_portwine/scripts/functions_helper

@@ -4514,7 +4514,7 @@ relaxed - Same as fifo but allows tearing when below the monitors refresh rate."
 
 # RESIZE PNG FILE
 resize_png () {
-    if [[ -z "$1" ]] || [[ -z "$2" ]] || [[ -z "$2" ]] ; then
+    if [[ -z "$1" ]] || [[ -z "$2" ]] || [[ -z "$3" ]] ; then
         print_error "no argument specified for resize_png"
         return 1
     else