Increase the error threshold.

Also increase the default exposure to better handle competition
conditions. (Set from calibration time at SFR)

Change-Id: I157315ad2950adda5915f0ca1d007888cd389198
diff --git a/aos/vision/image/camera_params.proto b/aos/vision/image/camera_params.proto
index c109154..947de96 100644
--- a/aos/vision/image/camera_params.proto
+++ b/aos/vision/image/camera_params.proto
@@ -10,7 +10,7 @@
   optional int32 height = 2 [default = 960];
 
   // Exposure setting.
-  optional int32 exposure = 3 [default = 10];
+  optional int32 exposure = 3 [default = 200];
 
   // Brightness setting.
   optional int32 brightness = 4 [default = 128];