1.2025.05.05: threshold: N.I.C.K.: new adjustment method

Author: zvezdochiot

src/imageproc/Binarize.cpp

@@ -619,7 +619,7 @@ BinaryImage binarizeBradley(
 }  // binarizeBradley
 
 /*
- * nick = mean - k * sqrt(stdev * stdev + mean * mean), k = 0.05
+ * nick = mean - k * sqrt(stdev * stdev + cnick * mean * mean), k = 0.10
  */
 BinaryImage binarizeNick(
     GrayImage const& src,
@@ -634,8 +634,8 @@ BinaryImage binarizeNick(
         return BinaryImage();
     }
 
-    GrayImage threshold_map(grayNickMap(src, radius, k));
-    BinaryImage bw_img(binarizeFromMap(src, threshold_map, delta, bound_lower, bound_upper));
+    GrayImage threshold_map(grayNickMap(src, radius, k, delta));
+    BinaryImage bw_img(binarizeFromMap(src, threshold_map, 0, bound_lower, bound_upper));
 
     return bw_img;
 }

src/imageproc/Binarize.h

@@ -205,7 +205,7 @@ IMAGEPROC_EXPORT BinaryImage binarizeBradley(
 IMAGEPROC_EXPORT BinaryImage binarizeNick(
     GrayImage const& src,
     int radius = 100,
-    float k = 0.05f,
+    float k = 0.10f,
     int delta = 0,
     unsigned char lower_bound = 0,
     unsigned char upper_bound = 255);

src/imageproc/GrayImage.cpp

@@ -906,12 +906,13 @@ GrayImage grayBradleyMap(
 }  // grayBradleyMap
 
 /*
- * nick = mean - k * sqrt(stdev * stdev + mean * mean), k = 0.05
+ * nick = mean - k * sqrt(stdev * stdev + cnick * mean * mean), k = 0.10
  */
 GrayImage grayNickMap(
     GrayImage const& src,
     int const radius,
-    float const k)
+    float const k,
+    int const delta)
 {
     if (src.isNull())
     {
@@ -925,6 +926,7 @@ GrayImage grayNickMap(
 
     if (radius > 0)
     {
+        float cnick = (50.0f - delta) * 0.01f;
         GrayImage gdeviation = grayMapDeviation(src, radius);
         if (gdeviation.isNull())
         {
@@ -944,7 +946,7 @@ GrayImage grayNickMap(
             {
                 float const mean = gmean_line[x];
                 float const deviation = gdeviation_line[x];
-                float const circle = sqrtf(deviation * deviation + mean * mean);
+                float const circle = sqrtf(deviation * deviation + cnick * mean * mean);
                 float threshold = mean - k * circle;
 
                 threshold = (threshold < 0.0f) ? 0.0f : ((threshold < 255.0f) ? threshold : 255.0f);

src/imageproc/GrayImage.h

@@ -203,7 +203,8 @@ IMAGEPROC_EXPORT GrayImage grayBradleyMap(
 IMAGEPROC_EXPORT GrayImage grayNickMap(
     GrayImage const& src,
     int radius = 100,
-    float k = 0.05f);
+    float k = 0.10f,
+    int delta = 0);
 IMAGEPROC_EXPORT GrayImage grayGradMap(
     GrayImage const& src,
     int radius = 10,

src/version.h

@@ -20,6 +20,6 @@
 #define SCANTAILOR_VERSION_H_
 
 #define STFAMILY "experimental"
-#define VERSION "1.2025.04.30" // Must be "x.x.x.x" or an empty string.
+#define VERSION "1.2025.05.05" // Must be "x.x.x.x" or an empty string.
 
 #endif