From c9683d2bb63611fea2a71c1c640b689ba2fcba29 Mon Sep 17 00:00:00 2001
From: zvezdochiot <mykaralw@yandex.ru>
Date: Tue, 13 Aug 2024 02:53:51 +0300
Subject: [PATCH] 1.0.20: threshold: new method Grad: lower/upper bound

---
 src/app/DefaultParamsDialog.cpp             | 6 +++---
 src/core/filters/output/OptionsWidget.cpp   | 2 +-
 src/core/filters/output/OutputGenerator.cpp | 6 ++++--
 src/imageproc/Binarize.cpp                  | 9 +++++++--
 src/imageproc/Binarize.h                    | 7 ++++++-
 5 files changed, 21 insertions(+), 9 deletions(-)

diff --git a/src/app/DefaultParamsDialog.cpp b/src/app/DefaultParamsDialog.cpp
index 982efd36..4bd4f852 100644
--- a/src/app/DefaultParamsDialog.cpp
+++ b/src/app/DefaultParamsDialog.cpp
@@ -667,10 +667,10 @@ std::unique_ptr<DefaultParams> DefaultParamsDialog::buildParams() const {
   blackWhiteOptions.setBinarizationMethod(binarizationMethod);
   blackWhiteOptions.setThresholdAdjustment(thresholdSlider->value());
   blackWhiteOptions.setSauvolaCoef(sauvolaCoef->value());
-  if (binarizationMethod == T_SAUVOLA || binarizationMethod == T_BRADLEY || binarizationMethod == T_GRAD
-      || binarizationMethod == T_EDGEPLUS || binarizationMethod == T_BLURDIV || binarizationMethod == T_EDGEDIV) {
+  if (binarizationMethod == T_SAUVOLA || binarizationMethod == T_BRADLEY || binarizationMethod == T_EDGEPLUS
+      || binarizationMethod == T_BLURDIV || binarizationMethod == T_EDGEDIV) {
     blackWhiteOptions.setWindowSize(sauvolaWindowSize->value());
-  } else if (binarizationMethod == T_WOLF) {
+  } else if (binarizationMethod == T_WOLF || binarizationMethod == T_GRAD) {
     blackWhiteOptions.setWindowSize(wolfWindowSize->value());
   }
   blackWhiteOptions.setWolfCoef(wolfCoef->value());
diff --git a/src/core/filters/output/OptionsWidget.cpp b/src/core/filters/output/OptionsWidget.cpp
index 8eb945b1..4abe91aa 100644
--- a/src/core/filters/output/OptionsWidget.cpp
+++ b/src/core/filters/output/OptionsWidget.cpp
@@ -58,7 +58,7 @@ OptionsWidget::OptionsWidget(std::shared_ptr<Settings> settings, const PageSelec
   QPointer<BinarizationOptionsWidget> wolfBinarizationOptionsWidget = new WolfBinarizationOptionsWidget(m_settings);
   QPointer<BinarizationOptionsWidget> bradleyBinarizationOptionsWidget
       = new SauvolaBinarizationOptionsWidget(m_settings);
-  QPointer<BinarizationOptionsWidget> gradBinarizationOptionsWidget = new SauvolaBinarizationOptionsWidget(m_settings);
+  QPointer<BinarizationOptionsWidget> gradBinarizationOptionsWidget = new WolfBinarizationOptionsWidget(m_settings);
   QPointer<BinarizationOptionsWidget> edgeplusBinarizationOptionsWidget
       = new SauvolaBinarizationOptionsWidget(m_settings);
   QPointer<BinarizationOptionsWidget> blurdivBinarizationOptionsWidget
diff --git a/src/core/filters/output/OutputGenerator.cpp b/src/core/filters/output/OutputGenerator.cpp
index bc44ea9c..9c8e5375 100644
--- a/src/core/filters/output/OutputGenerator.cpp
+++ b/src/core/filters/output/OutputGenerator.cpp
@@ -2330,9 +2330,11 @@ BinaryImage OutputGenerator::Processor::binarize(const QImage& image) const {
     case T_GRAD: {
       const double thresholdDelta = blackWhiteOptions.thresholdAdjustment();
       const QSize windowsSize = QSize(blackWhiteOptions.getWindowSize(), blackWhiteOptions.getWindowSize());
-      const double thresholdCoef = blackWhiteOptions.getSauvolaCoef();
+      const auto lowerBound = (unsigned char) blackWhiteOptions.getWolfLowerBound();
+      const auto upperBound = (unsigned char) blackWhiteOptions.getWolfUpperBound();
+      const double thresholdCoef = blackWhiteOptions.getWolfCoef();
 
-      binarized = binarizeGrad(image, windowsSize, thresholdCoef, thresholdDelta);
+      binarized = binarizeGrad(image, windowsSize, lowerBound, upperBound, thresholdCoef, thresholdDelta);
       break;
     }
     case T_EDGEPLUS: {
diff --git a/src/imageproc/Binarize.cpp b/src/imageproc/Binarize.cpp
index b24c6ef4..be434027 100644
--- a/src/imageproc/Binarize.cpp
+++ b/src/imageproc/Binarize.cpp
@@ -277,7 +277,12 @@ BinaryImage binarizeBradley(const QImage& src, const QSize windowSize, const dou
   return bwImg;
 }  // binarizeBradley
 
-BinaryImage binarizeGrad(const QImage& src, const QSize windowSize, const double k, const double delta) {
+BinaryImage binarizeGrad(const QImage& src,
+                         const QSize windowSize,
+                         const unsigned char lowerBound,
+                         const unsigned char upperBound,
+                         const double k,
+                         const double delta) {
   if (windowSize.isEmpty()) {
     throw std::invalid_argument("binarizeGrad: invalid windowSize");
   }
@@ -376,7 +381,7 @@ BinaryImage binarizeGrad(const QImage& src, const QSize windowSize, const double
       const double threshold = meanGrad + mean * k;
       const uint32_t msb = uint32_t(1) << 31;
       const uint32_t mask = msb >> (x & 31);
-      if (origin < (threshold + delta)) {
+      if ((grayLine[x] < lowerBound) || ((grayLine[x] <= upperBound) && (origin < (threshold + delta)))) {
         // black
         bwLine[x >> 5] |= mask;
       } else {
diff --git a/src/imageproc/Binarize.h b/src/imageproc/Binarize.h
index 481ff830..637d3c01 100644
--- a/src/imageproc/Binarize.h
+++ b/src/imageproc/Binarize.h
@@ -74,7 +74,12 @@ BinaryImage binarizeBradley(const QImage& src, QSize windowSize, double k = 0.34
  *
  * Grad (aka "Gradient snip"), zvezdochiot 2024. "Adaptive/global document image binarization".
  */
-BinaryImage binarizeGrad(const QImage& src, QSize windowSize, double k = 0.34, double delta = 0.0);
+BinaryImage binarizeGrad(const QImage& src,
+                         QSize windowSize,
+                         unsigned char lowerBound = 1,
+                         unsigned char upperBound = 254,
+                         double k = 0.3,
+                         double delta = 0.0);
 
 /**
  * \brief Image binarization using EdgeDiv (EdgePlus & BlurDiv) local/global thresholding method.