From 4735b5d89b4d79db5985e1482d0df45a0a99f3a0 Mon Sep 17 00:00:00 2001
From: Matt Hill <matthill@openalpr.com>
Date: Tue, 16 Feb 2016 15:17:15 -0500
Subject: [PATCH] Added prewarp reset by passing in empty prewarp config

---
 src/openalpr/alpr_impl.cpp | 5 ++++-
 src/openalpr/prewarp.cpp   | 3 +++
 src/openalpr/prewarp.h     | 1 +
 3 files changed, 8 insertions(+), 1 deletion(-)

diff --git a/src/openalpr/alpr_impl.cpp b/src/openalpr/alpr_impl.cpp
index f7579f1..69a9c50 100644
--- a/src/openalpr/alpr_impl.cpp
+++ b/src/openalpr/alpr_impl.cpp
@@ -661,7 +661,10 @@ namespace alpr
 
   void AlprImpl::setPrewarp(std::string prewarp_config)
   {
-    prewarp->initialize(prewarp_config);
+    if (prewarp_config.length() == 0)
+      prewarp ->clear();
+    else
+      prewarp->initialize(prewarp_config);
   }
 
 
diff --git a/src/openalpr/prewarp.cpp b/src/openalpr/prewarp.cpp
index 7a3a137..503feb7 100644
--- a/src/openalpr/prewarp.cpp
+++ b/src/openalpr/prewarp.cpp
@@ -103,6 +103,9 @@ namespace alpr
     if (config->debugTiming)
       cout << "Prewarp Initialization Time: " << diffclock(startTime, endTime) << "ms." << endl;
   }
+  void PreWarp::clear() {
+    this->valid = false;
+  }
 
   PreWarp::~PreWarp() {
   }
diff --git a/src/openalpr/prewarp.h b/src/openalpr/prewarp.h
index 6161682..d5af164 100644
--- a/src/openalpr/prewarp.h
+++ b/src/openalpr/prewarp.h
@@ -35,6 +35,7 @@ namespace alpr
     virtual ~PreWarp();
 
     void initialize(std::string prewarp_config);
+    void clear();
     
     cv::Mat warpImage(cv::Mat image);
     std::vector<cv::Point2f> projectPoints(std::vector<cv::Point2f> points, bool inverse);