Added always/never/auto invert config property to country config

runtime_data/config/au.conf

@@ -34,3 +34,8 @@ ocr_language = lau
 ; Override for postprocess letters/numbers regex. 
 postprocess_regex_letters = [A-Z]
 postprocess_regex_numbers = [0-9]
+
+
+; Whether the plate is always dark letters on light background, light letters on dark background, or both
+; value can be either always, never, or auto
+invert = auto

runtime_data/config/auwide.conf

@@ -35,3 +35,8 @@ ocr_language = lau
 ; Override for postprocess letters/numbers regex. 
 postprocess_regex_letters = [A-Z]
 postprocess_regex_numbers = [0-9]
+
+
+; Whether the plate is always dark letters on light background, light letters on dark background, or both
+; value can be either always, never, or auto
+invert = auto

runtime_data/config/eu.conf

@@ -36,3 +36,8 @@ ocr_language = leu
 ; Override for postprocess letters/numbers regex. 
 postprocess_regex_letters = [A-Z]
 postprocess_regex_numbers = [0-9]
+
+
+; Whether the plate is always dark letters on light background, light letters on dark background, or both
+; value can be either always, never, or auto
+invert = auto

runtime_data/config/kr.conf

@@ -35,3 +35,7 @@ ocr_language = lkr
 ; Override for postprocess letters/numbers regex. 
 postprocess_regex_letters = \pL
 postprocess_regex_numbers = \pN
+
+; Whether the plate is always dark letters on light background, light letters on dark background, or both
+; value can be either always, never, or auto
+invert = auto

runtime_data/config/us.conf

@@ -34,3 +34,7 @@ ocr_language = lus
 ; Override for postprocess letters/numbers regex. 
 postprocess_regex_letters = [A-Z]
 postprocess_regex_numbers = [0-9]
+
+; Whether the plate is always dark letters on light background, light letters on dark background, or both
+; value can be either always, never, or auto
+invert = auto

src/openalpr/config.cpp

@@ -219,6 +219,24 @@ namespace alpr
 
     multiline = 	getBoolean(ini, "", "multiline",		false);
 
+    string invert_val = getString(ini, "", "invert", "auto");
+
+    if (invert_val == "always")
+    {
+      auto_invert = false;
+      always_invert = true;
+    }
+    else if (invert_val == "never")
+    {
+      auto_invert = false;
+      always_invert = false;
+    }
+    else
+    {
+      auto_invert = true;
+      always_invert = false;
+    }
+
     plateWidthMM = getFloat(ini, "", "plate_width_mm", 100);
     plateHeightMM = getFloat(ini, "", "plate_height_mm", 100);
 

src/openalpr/config.h

@@ -54,6 +54,9 @@ namespace alpr
       
       bool skipDetection;
 
+      bool auto_invert;
+      bool always_invert;
+
       std::string prewarp;
       
       int maxPlateAngleDegrees;

src/openalpr/textdetection/characteranalysis.cpp

@@ -51,6 +51,9 @@ namespace alpr
     timespec startTime;
     getTimeMonotonic(&startTime);
 
+    if (config->always_invert)
+      bitwise_not(pipeline_data->crop_gray, pipeline_data->crop_gray);
+
     pipeline_data->clearThresholds();
     pipeline_data->thresholds = produceThresholds(pipeline_data->crop_gray, config);
 
@@ -177,7 +180,13 @@ namespace alpr
 
     }
 
-    pipeline_data->plate_inverted = isPlateInverted();
+    if (config->auto_invert)
+      pipeline_data->plate_inverted = isPlateInverted();
+    else
+      pipeline_data->plate_inverted = config->always_invert;
+
+    if (config->debugGeneral)
+      cout << "Plate inverted: " << pipeline_data->plate_inverted << endl;
 
 
     if (pipeline_data->textLines.size() > 0)