diff --git a/lib/Exd/DeviceToImage.pm b/lib/Exd/DeviceToImage.pm
index c7640c0..4c6ae26 100644
--- a/lib/Exd/DeviceToImage.pm
+++ b/lib/Exd/DeviceToImage.pm
@@ -18,6 +18,7 @@ has output_file => (
 has current_image => ( is => 'rw', );
 
 sub image( $self, $image ) {
+    $image->grayscale;
     my $current_image = $self->current_image;
 
     if ( !defined $current_image ) {