Merge pull request #37456 from alexbruy/gamma-correction

Gamma correction filter for raster layers
qgis · Jul 1, 2020 · 6068c64 · 6068c64
2 parents 059f9fa + 6a6f7ff
commit 6068c64
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Showing 25 changed files with 833 additions and 371 deletions.
diff --git a/images/images.qrc b/images/images.qrc
@@ -274,6 +274,7 @@
         <file>themes/default/mActionCustomProjection.svg</file>
         <file>themes/default/mActionDecreaseBrightness.svg</file>
         <file>themes/default/mActionDecreaseContrast.svg</file>
+        <file>themes/default/mActionDecreaseGamma.svg</file>
         <file>themes/default/mActionDeleteAttribute.svg</file>
         <file>themes/default/mActionDeletePart.svg</file>
         <file>themes/default/mActionDeleteRing.svg</file>
@@ -318,6 +319,7 @@
         <file>themes/default/mActionIdentify.svg</file>
         <file>themes/default/mActionIncreaseBrightness.svg</file>
         <file>themes/default/mActionIncreaseContrast.svg</file>
+        <file>themes/default/mActionIncreaseGamma.svg</file>
         <file>themes/default/mActionInOverview.svg</file>
         <file>themes/default/mActionInvertSelection.svg</file>
         <file>themes/default/mActionKeyboardShortcuts.svg</file>

diff --git a/images/themes/default/mActionDecreaseGamma.svg b/images/themes/default/mActionDecreaseGamma.svg
diff --git a/images/themes/default/mActionIncreaseGamma.svg b/images/themes/default/mActionIncreaseGamma.svg
diff --git a/python/core/auto_generated/raster/qgsbrightnesscontrastfilter.sip.in b/python/core/auto_generated/raster/qgsbrightnesscontrastfilter.sip.in
@@ -13,7 +13,7 @@
 class QgsBrightnessContrastFilter : QgsRasterInterface
 {
 %Docstring
-Brightness/contrast filter pipe for rasters.
+Brightness/contrast and gamma correction filter pipe for rasters.
 %End
 
 %TypeHeaderCode
@@ -24,27 +24,94 @@ Brightness/contrast filter pipe for rasters.
 
     virtual QgsBrightnessContrastFilter *clone() const /Factory/;
 
+%Docstring
+Clone itself, create deep copy
+%End
 
     virtual int bandCount() const;
 
+%Docstring
+Gets number of bands
+%End
 
     virtual Qgis::DataType dataType( int bandNo ) const;
 
+%Docstring
+Returns data type for the band specified by number
+%End
 
     virtual bool setInput( QgsRasterInterface *input );
 
+%Docstring
+Set input.
+Returns ``True`` if set correctly, ``False`` if cannot use that input
+%End
 
     virtual QgsRasterBlock *block( int bandNo, const QgsRectangle &extent, int width, int height, QgsRasterBlockFeedback *feedback = 0 ) /Factory/;
 
+%Docstring
+Read block of data using given extent and size.
+Returns pointer to data.
+Caller is responsible to free the memory returned.
+
+:param bandNo: band number
+:param extent: extent of block
+:param width: pixel width of block
+:param height: pixel height of block
+:param feedback: optional raster feedback object for cancellation/preview. Added in QGIS 3.0.
+%End
 
     void setBrightness( int brightness );
+%Docstring
+Set brightness level. Acceptable value range is -255…255
+
+.. seealso:: :py:func:`brightness`
+%End
+
     int brightness() const;
+%Docstring
+Returns current brightness level.
+
+.. seealso:: :py:func:`setBrightness`
+%End
 
     void setContrast( int contrast );
+%Docstring
+Set contrast level. Acceptable value range is -100…100
+
+.. seealso:: :py:func:`contrast`
+%End
+
     int contrast() const;
+%Docstring
+Returns current contrast level.
+
+.. seealso:: :py:func:`setContrast`
+%End
+
+    void setGamma( double gamma );
+%Docstring
+Set gamma value. Acceptable value range is -0.1…10
+
+.. seealso:: :py:func:`gamma`
+
+.. versionadded:: 3.16
+%End
+
+    double gamma() const;
+%Docstring
+Returns current gamma value.
+
+.. seealso:: :py:func:`setGamma`
+
+.. versionadded:: 3.16
+%End
 
     virtual void writeXml( QDomDocument &doc, QDomElement &parentElem ) const;
 
+%Docstring
+Write base class members to xml.
+%End
 
     virtual void readXml( const QDomElement &filterElem );
 

diff --git a/python/core/auto_generated/raster/qgsrasterpipe.sip.in b/python/core/auto_generated/raster/qgsrasterpipe.sip.in
@@ -30,7 +30,7 @@ Base class for processing modules.
       ResamplerRole,
       ProjectorRole,
       NullerRole,
-      HueSaturationRole
+      HueSaturationRole,
     };
 
     QgsRasterPipe();

diff --git a/src/app/qgisapp.cpp b/src/app/qgisapp.cpp
@@ -2785,6 +2785,8 @@ void QgisApp::createActions()
   connect( mActionDecreaseBrightness, &QAction::triggered, this, &QgisApp::decreaseBrightness );
   connect( mActionIncreaseContrast, &QAction::triggered, this, &QgisApp::increaseContrast );
   connect( mActionDecreaseContrast, &QAction::triggered, this, &QgisApp::decreaseContrast );
+  connect( mActionIncreaseGamma, &QAction::triggered, this, &QgisApp::increaseGamma );
+  connect( mActionDecreaseGamma, &QAction::triggered, this, &QgisApp::decreaseGamma );
 
 #ifdef HAVE_GEOREFERENCER
   connect( mActionShowGeoreferencer, &QAction::triggered, this, &QgisApp::showGeoreferencer );
@@ -3940,6 +3942,8 @@ void QgisApp::setTheme( const QString &themeName )
   mActionDecreaseBrightness->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionDecreaseBrightness.svg" ) ) );
   mActionIncreaseContrast->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionIncreaseContrast.svg" ) ) );
   mActionDecreaseContrast->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionDecreaseContrast.svg" ) ) );
+  mActionIncreaseGamma->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionIncreaseGamma.svg" ) ) );
+  mActionDecreaseGamma->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionDecreaseGamma.svg" ) ) );
   mActionZoomActualSize->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionZoomNative.png" ) ) );
   mActionQgisHomePage->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionQgisHomePage.png" ) ) );
   mActionAbout->setIcon( QgsApplication::getThemeIcon( QStringLiteral( "/mActionHelpAbout.svg" ) ) );
@@ -12210,6 +12214,54 @@ void QgisApp::adjustBrightnessContrast( int delta, bool updateBrightness )
   }
 }
 
+void QgisApp::increaseGamma()
+{
+  double step = 0.1;
+  if ( QgsApplication::keyboardModifiers() == Qt::ShiftModifier )
+  {
+    step = 1.0;
+  }
+  adjustGamma( step );
+}
+
+void QgisApp::decreaseGamma()
+{
+  double step = -0.1;
+  if ( QgsApplication::keyboardModifiers() == Qt::ShiftModifier )
+  {
+    step = -1.0;
+  }
+  adjustGamma( step );
+}
+
+void QgisApp::adjustGamma( double delta )
+{
+  const auto constSelectedLayers = mLayerTreeView->selectedLayers();
+  for ( QgsMapLayer *layer : constSelectedLayers )
+  {
+    if ( !layer )
+    {
+      visibleMessageBar()->pushMessage( tr( "No Layer Selected" ),
+                                        tr( "To change gamma, you need to have a raster layer selected." ),
+                                        Qgis::Info, messageTimeout() );
+      return;
+    }
+
+    QgsRasterLayer *rasterLayer = qobject_cast<QgsRasterLayer *>( layer );
+    if ( !rasterLayer )
+    {
+      visibleMessageBar()->pushMessage( tr( "No Layer Selected" ),
+                                        tr( "To change gamma, you need to have a raster layer selected." ),
+                                        Qgis::Info, messageTimeout() );
+      return;
+    }
+
+    QgsBrightnessContrastFilter *brightnessFilter = rasterLayer->brightnessFilter();
+    brightnessFilter->setGamma( brightnessFilter->gamma() + delta );
+
+    rasterLayer->triggerRepaint();
+  }
+}
 
 void QgisApp::helpContents()
 {

diff --git a/src/app/qgisapp.h b/src/app/qgisapp.h
@@ -1297,6 +1297,22 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
      * Decrease raster contrast
      * Valid for non wms raster layers only. */
     void decreaseContrast();
+
+    /**
+     * Increase raster gamma
+     * Valid for non wms raster layers only.
+     * \since QGIS 3.16
+     */
+    void increaseGamma();
+
+    /**
+     * Decrease raster gamma
+     * Valid for non wms raster layers only.
+     * \since QGIS 3.16
+     */
+    void decreaseGamma();
+
+
     //! plugin manager
     void showPluginManager();
     //! load Python support if possible
@@ -2104,9 +2120,15 @@ class APP_EXPORT QgisApp : public QMainWindow, private Ui::MainWindow
     //! Do histogram stretch for singleband gray / multiband color rasters
     void histogramStretch( bool visibleAreaOnly = false, QgsRasterMinMaxOrigin::Limits limits = QgsRasterMinMaxOrigin::MinMax );
 
-    //! Apply raster brightness
+    //! Apply raster brightness/contrast
     void adjustBrightnessContrast( int delta, bool updateBrightness = true );
 
+    /**
+     * Apply raster gamma
+     * \since QGIS 3.16
+     */
+    void adjustGamma( double delta );
+
     //! Copy a vector style from a layer to another one, if they have the same geometry type
     void duplicateVectorStyle( QgsVectorLayer *srcLayer, QgsVectorLayer *destLayer );
 

diff --git a/src/core/raster/qgsbrightnesscontrastfilter.cpp b/src/core/raster/qgsbrightnesscontrastfilter.cpp
@@ -32,6 +32,7 @@ QgsBrightnessContrastFilter *QgsBrightnessContrastFilter::clone() const
   QgsBrightnessContrastFilter *filter = new QgsBrightnessContrastFilter( nullptr );
   filter->setBrightness( mBrightness );
   filter->setContrast( mContrast );
+  filter->setGamma( mGamma );
   return filter;
 }
 
@@ -122,9 +123,9 @@ QgsRasterBlock *QgsBrightnessContrastFilter::block( int bandNo, QgsRectangle  co
     return outputBlock.release();
   }
 
-  if ( mBrightness == 0 && mContrast == 0 )
+  if ( mBrightness == 0 && mContrast == 0 && mGamma == 1.0 )
   {
-    QgsDebugMsgLevel( QStringLiteral( "No brightness changes." ), 4 );
+    QgsDebugMsgLevel( QStringLiteral( "No brightness/contrast/gamma changes." ), 4 );
     return inputBlock.release();
   }
 
@@ -139,6 +140,7 @@ QgsRasterBlock *QgsBrightnessContrastFilter::block( int bandNo, QgsRectangle  co
 
   int r, g, b, alpha;
   double f = std::pow( ( mContrast + 100 ) / 100.0, 2 );
+  double gammaCorrection = 1.0 / mGamma;
 
   for ( qgssize i = 0; i < ( qgssize )width * height; i++ )
   {
@@ -151,22 +153,22 @@ QgsRasterBlock *QgsBrightnessContrastFilter::block( int bandNo, QgsRectangle  co
     myColor = inputBlock->color( i );
     alpha = qAlpha( myColor );
 
-    r = adjustColorComponent( qRed( myColor ), alpha, mBrightness, f );
-    g = adjustColorComponent( qGreen( myColor ), alpha, mBrightness, f );
-    b = adjustColorComponent( qBlue( myColor ), alpha, mBrightness, f );
+    r = adjustColorComponent( qRed( myColor ), alpha, mBrightness, f, gammaCorrection );
+    g = adjustColorComponent( qGreen( myColor ), alpha, mBrightness, f, gammaCorrection );
+    b = adjustColorComponent( qBlue( myColor ), alpha, mBrightness, f, gammaCorrection );
 
     outputBlock->setColor( i, qRgba( r, g, b, alpha ) );
   }
 
   return outputBlock.release();
 }
 
-int QgsBrightnessContrastFilter::adjustColorComponent( int colorComponent, int alpha, int brightness, double contrastFactor ) const
+int QgsBrightnessContrastFilter::adjustColorComponent( int colorComponent, int alpha, int brightness, double contrastFactor, double gammaCorrection ) const
 {
   if ( alpha == 255 )
   {
     // Opaque pixel, do simpler math
-    return qBound( 0, ( int )( ( ( ( ( ( colorComponent / 255.0 ) - 0.5 ) * contrastFactor ) + 0.5 ) * 255 ) + brightness ), 255 );
+    return qBound( 0, ( int )( 255 * std::pow( ( ( ( ( ( ( colorComponent / 255.0 ) - 0.5 ) * contrastFactor ) + 0.5 ) * 255 ) + brightness ) / 255.0, gammaCorrection ) ), 255 );
   }
   else if ( alpha == 0 )
   {
@@ -181,7 +183,7 @@ int QgsBrightnessContrastFilter::adjustColorComponent( int colorComponent, int a
     double adjustedColor = colorComponent / alphaFactor;
 
     // Make sure to return a premultiplied color
-    return alphaFactor * qBound( 0., ( ( ( ( ( ( adjustedColor / 255.0 ) - 0.5 ) * contrastFactor ) + 0.5 ) * 255 ) + brightness ), 255. );
+    return alphaFactor * qBound( 0., std::pow( ( ( ( ( ( ( adjustedColor / 255.0 ) - 0.5 ) * contrastFactor ) + 0.5 ) * 255 ) + brightness ) / 255, gammaCorrection ), 255. );
   }
 }
 
@@ -196,6 +198,7 @@ void QgsBrightnessContrastFilter::writeXml( QDomDocument &doc, QDomElement &pare
 
   filterElem.setAttribute( QStringLiteral( "brightness" ), QString::number( mBrightness ) );
   filterElem.setAttribute( QStringLiteral( "contrast" ), QString::number( mContrast ) );
+  filterElem.setAttribute( QStringLiteral( "gamma" ), QString::number( mGamma ) );
   parentElem.appendChild( filterElem );
 }
 
@@ -208,4 +211,5 @@ void QgsBrightnessContrastFilter::readXml( const QDomElement &filterElem )
 
   mBrightness = filterElem.attribute( QStringLiteral( "brightness" ), QStringLiteral( "0" ) ).toInt();
   mContrast = filterElem.attribute( QStringLiteral( "contrast" ), QStringLiteral( "0" ) ).toInt();
+  mGamma = filterElem.attribute( QStringLiteral( "gamma" ), QStringLiteral( "1" ) ).toDouble();
 }