Add option to ignore page box for content detection

src/app/SettingsDialog.cpp

@@ -65,6 +65,8 @@ SettingsDialog::SettingsDialog(QWidget* parent) : QDialog(parent) {
   ui.blackOnWhiteDetectionAtOutputCB->setChecked(settings.isBlackOnWhiteDetectionOutputEnabled());
   connect(ui.blackOnWhiteDetectionCB, SIGNAL(clicked(bool)), SLOT(blackOnWhiteDetectionToggled(bool)));
 
+  ui.contentDetectionIgnorePageBoxCB->setChecked(settings.isContentDetectionIgnoringPageBox());
+
   ui.highlightDeviationCB->setChecked(settings.isHighlightDeviationEnabled());
 
   ui.deskewDeviationCoefSB->setValue(settings.getDeskewDeviationCoef());
@@ -109,6 +111,8 @@ void SettingsDialog::commitChanges() {
   settings.setBlackOnWhiteDetectionEnabled(ui.blackOnWhiteDetectionCB->isChecked());
   settings.setBlackOnWhiteDetectionOutputEnabled(ui.blackOnWhiteDetectionAtOutputCB->isChecked());
 
+  settings.setContentDetectionIgnoringPageBox(ui.contentDetectionIgnorePageBoxCB->isChecked());
+
   {
     const int quality = ui.thumbnailQualitySB->value();
     settings.setThumbnailQuality(QSize(quality, quality));

src/app/SettingsDialog.ui

@@ -319,6 +319,38 @@
          </layout>
         </widget>
        </item>
+       <item>
+        <widget class="QGroupBox" name="groupBox_5">
+         <property name="title">
+          <string>Content detection</string>
+         </property>
+         <layout class="QVBoxLayout" name="verticalLayout_8">
+          <item>
+           <widget class="QCheckBox" name="contentDetectionIgnorePageBoxCB">
+            <property name="text">
+             <string>Detect content independently of the page box</string>
+            </property>
+           </widget>
+          </item>
+          <item>
+           <widget class="QLabel" name="contentDetectionIgnorePageBoxLabel">
+            <property name="text">
+             <string>Use the whole image to search for content instead of only the area inside the page box. Useful when the page box noticeably deteriorates content recognition. The detected content box is still clipped to the page box afterwards. Re-run the Select Content stage to apply this to already processed pages.</string>
+            </property>
+            <property name="textFormat">
+             <enum>Qt::PlainText</enum>
+            </property>
+            <property name="wordWrap">
+             <bool>true</bool>
+            </property>
+            <property name="indent">
+             <number>20</number>
+            </property>
+           </widget>
+          </item>
+         </layout>
+        </widget>
+       </item>
        <item>
         <widget class="QGroupBox" name="groupBox_3">
          <property name="title">

src/app/main.cpp

@@ -11,6 +11,7 @@
 #include <core/StyledIconPack.h>
 
 #include <QGuiApplication>
+#include <QImageReader>
 #include <QSettings>
 #include <QStringList>
 
@@ -33,6 +34,14 @@ int main(int argc, char* argv[]) {
 #endif
   Application app(argc, argv);
 
+#if QT_VERSION >= QT_VERSION_CHECK(6, 0, 0)
+  // By default, Qt6 refuses to decode any image whose *uncompressed* size exceeds 256 MB,
+  // which is routinely hit by high-DPI scans of large pages.
+  if (!qEnvironmentVariableIsSet("QT_IMAGEIO_MAXALLOC")) {
+    QImageReader::setAllocationLimit(0);
+  }
+#endif
+
 #ifdef _WIN32
   // Get rid of all references to Qt's installation directory.
   Application::setLibraryPaths(QStringList(Application::applicationDirPath()));

src/core/ApplicationSettings.cpp

@@ -54,8 +54,10 @@ const QString ApplicationSettings::CURRENT_PROFILE_KEY = "current_profile";
 const QString ApplicationSettings::SHOW_CANCELING_SELECTION_QUESTION_KEY = "selection_canceling_question";
 const QString ApplicationSettings::DEFAULT_ZONE_CREATION_MODE_KEY = "default_zone_creation_mode";
 const QString ApplicationSettings::OUTPUT_SHOW_GUIDES_KEY = "output_show_guides";
+const QString ApplicationSettings::CONTENT_DETECTION_IGNORE_PAGE_BOX_KEY = "content_detection_ignore_page_box";
 const int ApplicationSettings::DEFAULT_ZONE_CREATION_MODE = 0;  // POLYGONAL
 const bool ApplicationSettings::DEFAULT_OUTPUT_SHOW_GUIDES = false;
+const bool ApplicationSettings::DEFAULT_CONTENT_DETECTION_IGNORE_PAGE_BOX = false;
 
 QString ApplicationSettings::getKey(const QString& keyName) {
   return ApplicationSettings::ROOT_KEY + '/' + keyName;
@@ -258,3 +260,12 @@ bool ApplicationSettings::isOutputShowGuidesEnabled() const {
 void ApplicationSettings::setOutputShowGuidesEnabled(bool enabled) {
   m_settings.setValue(getKey(OUTPUT_SHOW_GUIDES_KEY), enabled);
 }
+
+bool ApplicationSettings::isContentDetectionIgnoringPageBox() const {
+  return m_settings.value(getKey(CONTENT_DETECTION_IGNORE_PAGE_BOX_KEY), DEFAULT_CONTENT_DETECTION_IGNORE_PAGE_BOX)
+      .toBool();
+}
+
+void ApplicationSettings::setContentDetectionIgnoringPageBox(bool enabled) {
+  m_settings.setValue(getKey(CONTENT_DETECTION_IGNORE_PAGE_BOX_KEY), enabled);
+}

src/core/ApplicationSettings.h

@@ -114,6 +114,11 @@ class ApplicationSettings {
 
   void setOutputShowGuidesEnabled(bool enabled);
 
+  /** Disable page box masking when searching for content. */
+  bool isContentDetectionIgnoringPageBox() const;
+
+  void setContentDetectionIgnoringPageBox(bool enabled);
+
  private:
   static inline QString getKey(const QString& keyName);
 
@@ -163,9 +168,11 @@ class ApplicationSettings {
   static const QString SHOW_CANCELING_SELECTION_QUESTION_KEY;
   static const QString DEFAULT_ZONE_CREATION_MODE_KEY;
   static const QString OUTPUT_SHOW_GUIDES_KEY;
+  static const QString CONTENT_DETECTION_IGNORE_PAGE_BOX_KEY;
 
   static const int DEFAULT_ZONE_CREATION_MODE;  // 0 = polygonal
   static const bool DEFAULT_OUTPUT_SHOW_GUIDES;
+  static const bool DEFAULT_CONTENT_DETECTION_IGNORE_PAGE_BOX;
 
   QSettings m_settings;
 };

src/core/filters/select_content/ContentBoxFinder.cpp

@@ -19,6 +19,7 @@
 #include <SeedFill.h>
 #include <SlicedHistogram.h>
 #include <Transform.h>
+#include <core/ApplicationSettings.h>
 
 #include <QDebug>
 #include <QPainter>
@@ -97,11 +98,15 @@ QRectF ContentBoxFinder::findContentBox(const TaskStatus& status,
     dbg->add(bw150, "bw150");
   }
 
-  const double xscale = 150.0 / data.xform().origDpi().horizontal();
-  const double yscale = 150.0 / data.xform().origDpi().vertical();
-  QRectF pageRect150(pageRect.left() * xscale, pageRect.top() * yscale, pageRect.right() * xscale,
-                     pageRect.bottom() * yscale);
-  PolygonRasterizer::fillExcept(bw150, BLACK, pageRect150, Qt::WindingFill);
+  // Masking everything outside the page box sometimes leads to worse content detection.
+  // Skipping the mask lets the search use the whole image.
+  if (!ApplicationSettings::getInstance().isContentDetectionIgnoringPageBox()) {
+    const double xscale = 150.0 / data.xform().origDpi().horizontal();
+    const double yscale = 150.0 / data.xform().origDpi().vertical();
+    QRectF pageRect150(pageRect.left() * xscale, pageRect.top() * yscale, pageRect.right() * xscale,
+                       pageRect.bottom() * yscale);
+    PolygonRasterizer::fillExcept(bw150, BLACK, pageRect150, Qt::WindingFill);
+  }
 
   PolygonRasterizer::fillExcept(bw150, BLACK, xform150dpi.resultingPreCropArea(), Qt::WindingFill);
   if (dbg) {