Adjust exposure for 2018 fisheye camera

Change-Id: If4238386e6ffdc9767d74d0f114d683dcc1a1b59
diff --git a/y2018/vision/image_streamer.cc b/y2018/vision/image_streamer.cc
index f4ad36a..ce6f5e2 100644
--- a/y2018/vision/image_streamer.cc
+++ b/y2018/vision/image_streamer.cc
@@ -221,7 +221,7 @@
 
   TCPServer<MjpegDataSocket> tcp_serv_(80);
   aos::vision::CameraParams params;
-  params.set_exposure(300);
+  params.set_exposure(100);
   params.set_width(320);
   params.set_height(240);
   CameraStream camera(params, "/dev/video0", &tcp_serv_);