diff --git a/dev/optimize_images.sh b/dev/optimize_images.sh
index 0d532d054ad..2f8a84c57e7 100755
--- a/dev/optimize_images.sh
+++ b/dev/optimize_images.sh
@@ -6,7 +6,7 @@ PROGNAME=${0##*/}
 INPUT=''
 QUIET='0'
 NOSTATS='0'
-INPLACE='0'
+INPLACE='0'				 # (1=Images are replaced, 0=New images are stored into $OUTPUT)
 max_input_size=0
 max_output_size=0