Fix bugs in blob detector

When passing grayscale images by value, they can't be changed inside a
function. Also, fixed an infinite loop when more than 0 but less than 3
blobs were getting detected.

Signed-off-by: Milind Upadhyay <milind.upadhyay@gmail.com>
Change-Id: I5403d02aa9e3df07800791312f0e18ee81824868
diff --git a/y2022/vision/camera_reader.cc b/y2022/vision/camera_reader.cc
index 4ac6aad..732cf90 100644
--- a/y2022/vision/camera_reader.cc
+++ b/y2022/vision/camera_reader.cc
@@ -40,7 +40,7 @@
              << " on " << team_number;
 }
 
-void CameraReader::ProcessImage(const cv::Mat &image_mat) {
+void CameraReader::ProcessImage(cv::Mat image_mat) {
   // Remember, we're getting YUYV images, so we start by converting to RGB
 
   // TOOD: Need to code this up for blob detection