diff --git a/toonz/sources/include/tools/tool.h b/toonz/sources/include/tools/tool.h
index 39af9a4..28f5e16 100644
--- a/toonz/sources/include/tools/tool.h
+++ b/toonz/sources/include/tools/tool.h
@@ -59,9 +59,6 @@ class ToolOptionsBox;
 
 class QMenu;
 
-// iwsw commented out
-// class Ghibli3DLutUtil;
-
 //===================================================================
 
 //*****************************************************************************************
@@ -655,8 +652,8 @@ public:
   /*-- Toolで画面の内外を判断するため --*/
   virtual TRectD getGeometry() const = 0;
 
-  // iwsw commented out
-  // virtual Ghibli3DLutUtil* get3DLutUtil(){ return 0; }
+  virtual void bindFBO() {}
+  virtual void releaseFBO() {}
 };
 
 #endif
diff --git a/toonz/sources/include/toonz/preferences.h b/toonz/sources/include/toonz/preferences.h
index 801ca00..69dbf6d 100644
--- a/toonz/sources/include/toonz/preferences.h
+++ b/toonz/sources/include/toonz/preferences.h
@@ -235,6 +235,15 @@ public:
   void setInterfaceFontWeight(int weight);
   int getInterfaceFontWeight() { return m_interfaceFontWeight; }
 
+  // color calibration using 3DLUT
+  void enableColorCalibration(bool on);
+  bool isColorCalibrationEnabled() const { return m_colorCalibrationEnabled; }
+  void setColorCalibrationLutPath(QString monitorName, QString path);
+  QMap<QString, QString> &getColorCalibrationLutPathMap() {
+    return m_colorCalibrationLutPaths;
+  }
+  QString getColorCalibrationLutPath(QString &monitorName) const;
+
   // Visualization  tab
 
   void setShow0ThickLines(bool on);
@@ -652,6 +661,12 @@ private:
 
   bool m_currentTimelineEnabled;
 
+  // color calibration using 3DLUT
+  bool m_colorCalibrationEnabled = true;  //とりあえず
+  // map of [monitor name]-[path to the lut file].
+  // for now non-Windows accepts only one lut path for all kinds of monitors
+  QMap<QString, QString> m_colorCalibrationLutPaths;
+
 private:
   Preferences();
   ~Preferences();
diff --git a/toonz/sources/include/toonzqt/lutcalibrator.h b/toonz/sources/include/toonzqt/lutcalibrator.h
new file mode 100644
index 0000000..f70981b
--- /dev/null
+++ b/toonz/sources/include/toonzqt/lutcalibrator.h
@@ -0,0 +1,78 @@
+#pragma once
+
+#ifndef LUT_CALIBRATOR_H
+#define LUT_CALIBRATOR_H
+
+#include "tcommon.h"
+#include "tpixelutils.h"
+
+#include <QOpenGLBuffer>
+#include <QMatrix4x4>
+#include <QOpenGLFunctions>
+
+#undef DVAPI
+#undef DVVAR
+#ifdef TOONZQT_EXPORTS
+#define DVAPI DV_EXPORT_API
+#define DVVAR DV_EXPORT_VAR
+#else
+#define DVAPI DV_IMPORT_API
+#define DVVAR DV_IMPORT_VAR
+#endif
+
+class QOpenGLShader;
+class QOpenGLShaderProgram;
+class QOpenGLFramebufferObject;
+class QOpenGLTexture;
+
+class QColor;
+
+class DVAPI LutCalibrator : public QOpenGLFunctions  // sigleton
+{
+  bool m_isValid = false;
+
+  struct LutTextureShader {
+    QOpenGLShader* vert           = nullptr;
+    QOpenGLShader* frag           = nullptr;
+    QOpenGLShaderProgram* program = nullptr;
+    int texUniform                = -1;
+    int lutUniform                = -1;
+    int lutSizeUniform            = -1;
+    int vertexAttrib              = -1;
+    int texCoordAttrib            = -1;
+  } m_shader;
+
+  struct Lut {
+    int meshSize;
+    float* data         = NULL;
+    QOpenGLTexture* tex = NULL;
+  } m_lut;
+
+  QOpenGLBuffer m_viewerVBO;
+  LutCalibrator() {}
+
+  bool initializeLutTextureShader();
+  void createViewerVBO();
+  bool loadLutFile(const QString& path);
+  void assignLutTexture();
+
+public:
+  static LutCalibrator* instance();
+
+  // to be computed once through the software
+  void initialize();
+  void finalize();
+  bool isValid() { return m_isValid; }
+
+  ~LutCalibrator() { finalize(); }
+
+  void onEndDraw(QOpenGLFramebufferObject*);
+
+  QString& getMonitorName() const;
+
+  void convert(float&, float&, float&);
+  void convert(QColor&);
+  void convert(TPixel32&);
+};
+
+#endif
\ No newline at end of file
diff --git a/toonz/sources/include/toonzqt/styleeditor.h b/toonz/sources/include/toonzqt/styleeditor.h
index 8a40c05..040dee9 100644
--- a/toonz/sources/include/toonzqt/styleeditor.h
+++ b/toonz/sources/include/toonzqt/styleeditor.h
@@ -14,7 +14,6 @@
 #include "toonz/tpalettehandle.h"
 #include "toonz/txshlevelhandle.h"
 #include "toonz/txshlevel.h"
-//#include "toonz/preferences.h" //iwsw commented out temporarily
 
 // TnzQt includes
 #include "toonzqt/checkbox.h"
@@ -24,9 +23,6 @@
 #include "toonzqt/tabbar.h"
 #include "toonzqt/glwidget_for_highdpi.h"
 
-// Toonz includes
-//#include "../toonz/tapp.h" //iwsw commented out temporarily
-
 // Qt includes
 #include <QWidget>
 #include <QFrame>
@@ -39,9 +35,6 @@
 #include <QSettings>
 #include <QSplitter>
 
-// iwsw commented out temporarily
-//#include "ghibli_3dlut_util.h"
-
 #undef DVAPI
 #undef DVVAR
 #ifdef TOONZQT_EXPORTS
@@ -71,6 +64,7 @@ class QButtonGroup;
 class QPushButton;
 class QTabWidget;
 class QToolBar;
+class QOpenGLFramebufferObject;
 
 class ColorSquaredWheel;
 class TabBarContainter;
@@ -153,8 +147,8 @@ class DVAPI HexagonalColorWheel final : public GLWidgetForHighDpi {
 
   CurrentWheel m_currentWheel;
 
-  // iwsw commented out temporarily  about 3DLUT
-  // Ghibli3DLutUtil * m_ghibli3DLutUtil;
+  // used for color calibration with 3DLUT
+  QOpenGLFramebufferObject *m_fbo = NULL;
 
 private:
   void drawCurrentColorMark();
diff --git a/toonz/sources/tnztools/brushtool.cpp b/toonz/sources/tnztools/brushtool.cpp
index 9c9a7d8..c3a461a 100644
--- a/toonz/sources/tnztools/brushtool.cpp
+++ b/toonz/sources/tnztools/brushtool.cpp
@@ -2087,8 +2087,8 @@ void BrushTool::checkGuideSnapping(bool beforeMousePress) {
         snapPoint.x = hGuide;
       }
       beforeMousePress ? m_foundFirstSnap = true : m_foundLastSnap = true;
-      beforeMousePress ? m_firstSnapPoint = snapPoint : m_lastSnapPoint =
-                                                            snapPoint;
+      beforeMousePress ? m_firstSnapPoint                          = snapPoint
+                       : m_lastSnapPoint                           = snapPoint;
     }
   }
 }
diff --git a/toonz/sources/tnztools/rgbpickertool.cpp b/toonz/sources/tnztools/rgbpickertool.cpp
index 72b5092..a1c3ebf 100644
--- a/toonz/sources/tnztools/rgbpickertool.cpp
+++ b/toonz/sources/tnztools/rgbpickertool.cpp
@@ -22,15 +22,13 @@
 
 #include "toonzqt/icongenerator.h"
 #include "toonzqt/dvdialog.h"
+#include "toonzqt/lutcalibrator.h"
 
 #include "tools/toolhandle.h"
 #include "tools/stylepicker.h"
 #include "tools/toolutils.h"
 #include "tools/RGBpicker.h"
 
-// iwsw  commented out temporarily
-//#include "toonzqt/ghibli_3dlut_util.h"
-
 #define NORMAL_PICK L"Normal"
 #define RECT_PICK L"Rectangular"
 #define FREEHAND_PICK L"Freehand"
@@ -420,8 +418,12 @@ void RGBPickerTool::passivePick() {
 
   StylePicker picker(image);
 
+  if (LutCalibrator::instance()->isValid()) m_viewer->bindFBO();
+
   TPixel32 pix = picker.pickColor(area);
 
+  if (LutCalibrator::instance()->isValid()) m_viewer->releaseFBO();
+
   QColor col((int)pix.r, (int)pix.g, (int)pix.b);
 
   PaletteController *controller =
@@ -444,8 +446,12 @@ void RGBPickerTool::pick() {
                        m_mousePixelPosition.x + 1, m_mousePixelPosition.y + 1);
   StylePicker picker(image, palette);
 
+  if (LutCalibrator::instance()->isValid()) m_viewer->bindFBO();
+
   m_currentValue = picker.pickColor(area);
 
+  if (LutCalibrator::instance()->isValid()) m_viewer->releaseFBO();
+
   TXshSimpleLevel *level = app->getCurrentLevel()->getSimpleLevel();
   UndoPickRGBM *cmd = new UndoPickRGBM(palette, styleId, m_currentValue, level);
   TUndoManager::manager()->add(cmd);
@@ -485,7 +491,11 @@ void RGBPickerTool::pickRect() {
   if (area.getLx() <= 1 || area.getLy() <= 1) return;
   StylePicker picker(image, palette);
 
+  if (LutCalibrator::instance()->isValid()) m_viewer->bindFBO();
+
   m_currentValue = picker.pickColor(area);
+
+  if (LutCalibrator::instance()->isValid()) m_viewer->releaseFBO();
 }
 
 //---------------------------------------------------------
@@ -502,8 +512,12 @@ void RGBPickerTool::pickStroke() {
   StylePicker picker(image, palette);
   TStroke *stroke = new TStroke(*m_stroke);
 
+  if (LutCalibrator::instance()->isValid()) m_viewer->bindFBO();
+
   m_currentValue = picker.pickColor(stroke);
 
+  if (LutCalibrator::instance()->isValid()) m_viewer->releaseFBO();
+
   if (!(m_pickType.getValue() == POLYLINE_PICK)) {
     TXshSimpleLevel *level = app->getCurrentLevel()->getSimpleLevel();
     TUndoManager::manager()->add(
diff --git a/toonz/sources/tnztools/tooloptions.cpp b/toonz/sources/tnztools/tooloptions.cpp
index fdbc903..d67580d 100644
--- a/toonz/sources/tnztools/tooloptions.cpp
+++ b/toonz/sources/tnztools/tooloptions.cpp
@@ -22,8 +22,7 @@
 #include "toonzqt/menubarcommand.h"
 #include "toonzqt/gutil.h"
 #include "toonzqt/dvscrollwidget.h"
-// iwsw commented out temporarily
-//#include "toonzqt/ghibli_3dlut_converter.h"
+#include "toonzqt/lutcalibrator.h"
 
 // TnzLib includes
 #include "toonz/tobjecthandle.h"
@@ -2279,18 +2278,12 @@ protected:
     QPainter p(this);
     p.setPen(Qt::NoPen);
 
-    // iwsw commented out temporarily
-    /*
-    if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-    {
-            QColor convertedColor(m_color);
-            Ghibli3DLutConverter::instance()->convert(convertedColor);
-            p.setBrush(convertedColor);
-    }
-    else
-    */
-    p.setBrush(m_color);
-    p.setBrush(m_color);
+    if (LutCalibrator::instance()->isValid()) {
+      QColor convertedColor(m_color);
+      LutCalibrator::instance()->convert(convertedColor);
+      p.setBrush(convertedColor);
+    } else
+      p.setBrush(m_color);
 
     p.drawRect(rect());
 
diff --git a/toonz/sources/toonz/imageviewer.cpp b/toonz/sources/toonz/imageviewer.cpp
index f4abded..77ec6c9 100644
--- a/toonz/sources/toonz/imageviewer.cpp
+++ b/toonz/sources/toonz/imageviewer.cpp
@@ -20,6 +20,7 @@
 #include "toonzqt/menubarcommand.h"
 #include "toonzqt/viewcommandids.h"
 #include "toonzqt/imageutils.h"
+#include "toonzqt/lutcalibrator.h"
 
 // TnzLib includes
 #include "toonz/tscenehandle.h"
@@ -36,6 +37,7 @@
 #include <QAction>
 #include <QMouseEvent>
 #include <QWheelEvent>
+#include <QOpenGLFramebufferObject>
 
 //===================================================================================
 
@@ -226,11 +228,6 @@ ImageViewer::ImageViewer(QWidget *parent, FlipBook *flipbook,
 
   if (m_isHistogramEnable)
     m_histogramPopup = new HistogramPopup(tr("Flipbook Histogram"));
-
-  // iwsw commented out 2 lines temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // Ghibli3DLutUtil::m_isValid)
-  //	m_ghibli3DLutUtil = new Ghibli3DLutUtil();
 }
 
 //-----------------------------------------------------------------------------
@@ -365,6 +362,7 @@ ImageViewer::~ImageViewer() {
           delete m_ghibli3DLutUtil;
   }
   */
+  if (m_fbo) delete m_fbo;
 }
 
 //-----------------------------------------------------------------------------
@@ -413,13 +411,12 @@ void ImageViewer::hideHistogram() {
 
 void ImageViewer::initializeGL() {
   initializeOpenGLFunctions();
+
+  // to be computed once through the software
+  LutCalibrator::instance()->initialize();
+
   // glClearColor(1.0,1.0,1.0,1);
   glClear(GL_COLOR_BUFFER_BIT);
-
-  // iwsw commented out temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // m_ghibli3DLutUtil)
-  //  m_ghibli3DLutUtil->onInit();
 }
 
 //-----------------------------------------------------------------------------
@@ -439,19 +436,17 @@ void ImageViewer::resizeGL(int w, int h) {
   glTranslatef(0.375, 0.375, 0.0);
   glTranslated(w * 0.5, h * 0.5, 0);
 
-  // iwsw commented out temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // m_ghibli3DLutUtil)
-  //	m_ghibli3DLutUtil->onResize(w, h);
+  // remake fbo with new size
+  if (LutCalibrator::instance()->isValid()) {
+    if (m_fbo) delete m_fbo;
+    m_fbo = new QOpenGLFramebufferObject(w, h);
+  }
 }
 
 //-----------------------------------------------------------------------------
 
 void ImageViewer::paintGL() {
-  // iwsw commented out temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // m_ghibli3DLutUtil)
-  //	m_ghibli3DLutUtil->startDraw();
+  if (LutCalibrator::instance()->isValid()) m_fbo->bind();
 
   TDimension viewerSize(width(), height());
   TAffine aff = m_viewAff;
@@ -508,11 +503,8 @@ void ImageViewer::paintGL() {
   }
 
   if (!m_image) {
-    // iwsw commented out temporarily
-    // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-    // m_ghibli3DLutUtil)
-    //	m_ghibli3DLutUtil->endDraw();
-
+    if (LutCalibrator::instance()->isValid())
+      LutCalibrator::instance()->onEndDraw(m_fbo);
     return;
   }
 
@@ -590,10 +582,8 @@ void ImageViewer::paintGL() {
     }
   }
 
-  // iwsw commented out temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // m_ghibli3DLutUtil)
-  //  m_ghibli3DLutUtil->endDraw();
+  if (LutCalibrator::instance()->isValid())
+    LutCalibrator::instance()->onEndDraw(m_fbo);
 }
 
 //------------------------------------------------------------------------------
@@ -851,17 +841,11 @@ void ImageViewer::pickColor(QMouseEvent *event, bool putValueToStyleEditor) {
   TPoint mousePos = TPoint(curPos.x(), height() - 1 - curPos.y());
   TRectD area     = TRectD(mousePos.x, mousePos.y, mousePos.x, mousePos.y);
 
-  // iwsw commented out temporarily
-  // if (get3DLutUtil() &&
-  // Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-  //	get3DLutUtil()->bindFBO();
+  if (LutCalibrator::instance()->isValid()) m_fbo->bind();
 
   const TPixel32 pix = picker.pickColor(area);
 
-  // iwsw commented out temporarily
-  // if (get3DLutUtil() &&
-  // Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-  //	get3DLutUtil()->releaseFBO();
+  if (LutCalibrator::instance()->isValid()) m_fbo->release();
 
   QPoint viewP = mapFrom(this, curPos);
   TPointD pos  = getViewAff().inv() *
@@ -899,17 +883,11 @@ void ImageViewer::rectPickColor(bool putValueToStyleEditor) {
     return;
   }
 
-  // iwsw commented out temporarily
-  // if (get3DLutUtil() &&
-  // Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-  //	get3DLutUtil()->bindFBO();
+  if (LutCalibrator::instance()->isValid() && m_fbo) m_fbo->bind();
 
   const TPixel32 pix = picker.pickColor(area.enlarge(-1, -1));
 
-  // iwsw commented out temporarily
-  // if (get3DLutUtil() &&
-  // Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-  //	get3DLutUtil()->releaseFBO();
+  if (LutCalibrator::instance()->isValid() && m_fbo) m_fbo->release();
 
   // throw the picked color to the histogram
   m_histogramPopup->updateAverageColor(pix);
diff --git a/toonz/sources/toonz/imageviewer.h b/toonz/sources/toonz/imageviewer.h
index d8c905b..857e59a 100644
--- a/toonz/sources/toonz/imageviewer.h
+++ b/toonz/sources/toonz/imageviewer.h
@@ -3,9 +3,6 @@
 #ifndef IMAGEVIEWER_INCLUDE
 #define IMAGEVIEWER_INCLUDE
 
-// iwsw commented out temporarily
-//#include "toonzqt/ghibli_3dlut_util.h"
-
 #include "toonz/imagepainter.h"
 #include "toonzqt/glwidget_for_highdpi.h"
 
@@ -14,6 +11,7 @@
 //  Forward declarations
 class FlipBook;
 class HistogramPopup;
+class QOpenGLFramebufferObject;
 
 //-----------------------------------------------------------------------------
 
@@ -57,8 +55,8 @@ class ImageViewer final : public GLWidgetForHighDpi {
   // a flipbook shows a red border line before the rendered result is shown.
   bool m_isRemakingPreviewFx;
 
-  // iwsw commented out temporarily
-  // Ghibli3DLutUtil * m_ghibli3DLutUtil;
+  // used for color calibration with 3DLUT
+  QOpenGLFramebufferObject *m_fbo = NULL;
 
   int getDragType(const TPoint &pos, const TRect &loadBox);
   void updateLoadbox(const TPoint &curPos);
@@ -109,9 +107,6 @@ public:
   void doSwapBuffers();
   void changeSwapBehavior(bool enable);
 
-  // iwsw commented out temporarily
-  // Ghibli3DLutUtil* get3DLutUtil(){ return m_ghibli3DLutUtil; }
-
 protected:
   void contextMenuEvent(QContextMenuEvent *event) override;
   void initializeGL() override;
diff --git a/toonz/sources/toonz/main.cpp b/toonz/sources/toonz/main.cpp
index 7fa0819..3619742 100644
--- a/toonz/sources/toonz/main.cpp
+++ b/toonz/sources/toonz/main.cpp
@@ -25,8 +25,6 @@
 #include "toonzqt/icongenerator.h"
 #include "toonzqt/gutil.h"
 #include "toonzqt/pluginloader.h"
-// iwsw commented out temporarily
-//#include "toonzqt/ghibli_3dlut_util.h"
 
 // TnzStdfx includes
 #include "stdfx/shaderfx.h"
@@ -532,32 +530,6 @@ int main(int argc, char *argv[]) {
   TTool::setApplication(TApp::instance());
   TApp::instance()->init();
 
-// iwsw commented out temporarily
-#if 0
-  QStringList monitorNames;
-  /*-- 接続モニタがPVM-2541の場合のみLUTを読み込む --*/
-  if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-  {
-	  /*-- 接続モニタがPVM-2541の場合のみLUTを読み込む --*/
-	  monitorNames = Ghibli3DLutUtil::getMonitorName();
-	  if (monitorNames.contains(QString::fromStdWString(L"PVM-2541")))
-		  /*-- 3DLUTファイルを読み込む --*/
-		  Ghibli3DLutUtil::loadLutFile(Preferences::instance()->get3DLutPath());
-  }
-  /*-- 接続モニタをスプラッシュ画面にも表示 --*/
-  if (!monitorNames.isEmpty())
-  {
-	  lastUpdateStr += QString("Monitor Name : ");
-	  for (int mn = 0; mn < monitorNames.size(); mn++)
-	  {
-		  if (mn != 0)
-			  lastUpdateStr += QString(", ");
-		  lastUpdateStr += monitorNames.at(mn);
-	  }
-	  lastUpdateStr += QString("\n");
-  }
-#endif
-
   splash.showMessage(offsetStr + "Loading Plugins...", Qt::AlignCenter,
                      Qt::white);
   a.processEvents();
diff --git a/toonz/sources/toonz/preferencespopup.cpp b/toonz/sources/toonz/preferencespopup.cpp
index 1c04676..de2dbd4 100644
--- a/toonz/sources/toonz/preferencespopup.cpp
+++ b/toonz/sources/toonz/preferencespopup.cpp
@@ -17,6 +17,7 @@
 #include "toonzqt/doublefield.h"
 #include "toonzqt/dvdialog.h"
 #include "toonzqt/filefield.h"
+#include "toonzqt/lutcalibrator.h"
 
 // TnzLib includes
 #include "toonz/txsheethandle.h"
@@ -1145,6 +1146,20 @@ void PreferencesPopup::onShowCurrentTimelineChanged(int index) {
   m_pref->enableCurrentTimelineIndicator(index == Qt::Checked);
 }
 
+//-----------------------------------------------------------------------------
+
+void PreferencesPopup::onColorCalibrationChanged(bool on) {
+  m_pref->enableColorCalibration(on);
+}
+
+//-----------------------------------------------------------------------------
+
+void PreferencesPopup::onLutPathChanged() {
+  m_pref->setColorCalibrationLutPath(
+      LutCalibrator::instance()->getMonitorName(),
+      m_lutPathFileField->getPath());
+}
+
 //**********************************************************************************
 //    PrefencesPopup's  constructor
 //**********************************************************************************
@@ -1259,6 +1274,11 @@ PreferencesPopup::PreferencesPopup()
   m_interfaceFont       = new QComboBox(this);
   m_interfaceFontWeight = new QComboBox(this);
 
+  m_colorCalibration =
+      new QGroupBox(tr("Color Calibration using 3D Look-up Table *"));
+  m_lutPathFileField = new DVGui::FileField(
+      this, QString("- Please specify 3DLUT file (.3dl) -"), false, true);
+
   //--- Visualization ------------------------------
   categoryList->addItem(tr("Visualization"));
   CheckBox *show0ThickLinesCB =
@@ -1583,6 +1603,16 @@ PreferencesPopup::PreferencesPopup()
   m_interfaceFontWeight->addItems(fontStyles);
   m_interfaceFontWeight->setCurrentIndex(m_pref->getInterfaceFontWeight());
 
+  m_colorCalibration->setCheckable(true);
+  m_colorCalibration->setChecked(m_pref->isColorCalibrationEnabled());
+  QString lutPath = m_pref->getColorCalibrationLutPath(
+      LutCalibrator::instance()->getMonitorName());
+  if (!lutPath.isEmpty()) m_lutPathFileField->setPath(lutPath);
+  m_lutPathFileField->setFileMode(QFileDialog::ExistingFile);
+  QStringList lutFileTypes;
+  lutFileTypes << "3dl";
+  m_lutPathFileField->setFilters(lutFileTypes);
+
   //--- Visualization ------------------------------
   show0ThickLinesCB->setChecked(m_pref->getShow0ThickLines());
   regionAntialiasCB->setChecked(m_pref->getRegionAntialias());
@@ -1985,6 +2015,20 @@ PreferencesPopup::PreferencesPopup()
       interfaceBottomLay->setColumnStretch(5, 1);
       userInterfaceFrameLay->addLayout(interfaceBottomLay, 0);
 
+      QHBoxLayout *lutLayout = new QHBoxLayout();
+      lutLayout->setMargin(10);
+      lutLayout->setSpacing(5);
+      {
+        lutLayout->addWidget(
+            new QLabel(tr("3DLUT File for [%1] *:")
+                           .arg(LutCalibrator::instance()->getMonitorName()),
+                       this),
+            0);
+        lutLayout->addWidget(m_lutPathFileField, 1);
+      }
+      m_colorCalibration->setLayout(lutLayout);
+      userInterfaceFrameLay->addWidget(m_colorCalibration);
+
       userInterfaceFrameLay->addStretch(1);
 
       userInterfaceFrameLay->addWidget(note_interface, 0);
@@ -2562,6 +2606,11 @@ PreferencesPopup::PreferencesPopup()
   ret = ret && connect(levelNameOnEachMarkerCB, SIGNAL(stateChanged(int)),
                        SLOT(onLevelNameOnEachMarkerChanged(int)));
 
+  ret = ret && connect(m_colorCalibration, SIGNAL(clicked(bool)), this,
+                       SLOT(onColorCalibrationChanged(bool)));
+  ret = ret && connect(m_lutPathFileField, SIGNAL(pathChanged()), this,
+                       SLOT(onLutPathChanged()));
+
   //--- Visualization ---------------------
   ret = ret && connect(show0ThickLinesCB, SIGNAL(stateChanged(int)), this,
                        SLOT(onShow0ThickLinesChanged(int)));
diff --git a/toonz/sources/toonz/preferencespopup.h b/toonz/sources/toonz/preferencespopup.h
index 231b107..30e52f8 100644
--- a/toonz/sources/toonz/preferencespopup.h
+++ b/toonz/sources/toonz/preferencespopup.h
@@ -81,9 +81,10 @@ private:
 
   DVGui::FileField *m_customProjectRootFileField;
 
-  DVGui::FileField *m_ffmpegPathFileFld, *m_fastRenderPathFileField;
+  DVGui::FileField *m_ffmpegPathFileFld, *m_fastRenderPathFileField,
+      *m_lutPathFileField;
 
-  QGroupBox *m_autoSaveGroup, *m_showXSheetToolbar;
+  QGroupBox *m_autoSaveGroup, *m_showXSheetToolbar, *m_colorCalibration;
 
 private:
   // QWidget* create(const QString& lbl, bool def, const char* slot);
@@ -200,6 +201,8 @@ private slots:
   void onXsheetLayoutChanged(const QString &text);
   void onPathAliasPriorityChanged(int index);
   void onShowCurrentTimelineChanged(int);
+  void onColorCalibrationChanged(bool);
+  void onLutPathChanged();
 };
 
 //**********************************************************************************
diff --git a/toonz/sources/toonz/sceneviewer.cpp b/toonz/sources/toonz/sceneviewer.cpp
index ab1c453..a9ea660 100644
--- a/toonz/sources/toonz/sceneviewer.cpp
+++ b/toonz/sources/toonz/sceneviewer.cpp
@@ -23,6 +23,7 @@
 #include "toonzqt/icongenerator.h"
 #include "toonzqt/gutil.h"
 #include "toonzqt/imageutils.h"
+#include "toonzqt/lutcalibrator.h"
 
 // TnzLib includes
 #include "toonz/tscenehandle.h"
@@ -81,6 +82,7 @@
 #include <QInputContext>
 #endif
 #include <QGLContext>
+#include <QOpenGLFramebufferObject>
 
 #include "sceneviewer.h"
 
@@ -500,10 +502,6 @@ SceneViewer::SceneViewer(ImageUtils::FullScreenWidget *parent)
   m_3DSideL = rasterFromQPixmap(svgToPixmap(":Resources/3Dside_l.svg"));
   m_3DTop   = rasterFromQPixmap(svgToPixmap(":Resources/3Dtop.svg"));
 
-  // iwsw commented out temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // Ghibli3DLutUtil::m_isValid)
-  //  m_ghibli3DLutUtil = new Ghibli3DLutUtil();
   setAttribute(Qt::WA_AcceptTouchEvents);
   grabGesture(Qt::SwipeGesture);
   grabGesture(Qt::PanGesture);
@@ -525,14 +523,7 @@ void SceneViewer::setVisual(const ImagePainter::VisualSettings &settings) {
 //-----------------------------------------------------------------------------
 
 SceneViewer::~SceneViewer() {
-  // iwsw commented out temporarily
-  /*
-if (m_ghibli3DLutUtil)
-{
-    m_ghibli3DLutUtil->onEnd();
-    delete m_ghibli3DLutUtil;
-}
-*/
+  if (m_fbo) delete m_fbo;
 }
 
 //-------------------------------------------------------------------------------
@@ -825,13 +816,12 @@ double SceneViewer::getHGuide(int index) { return m_hRuler->getGuide(index); }
 
 void SceneViewer::initializeGL() {
   initializeOpenGLFunctions();
+
+  // to be computed once through the software
+  LutCalibrator::instance()->initialize();
+
   // glClearColor(1.0,1.0,1.0,1);
   glClear(GL_COLOR_BUFFER_BIT);
-
-  // iwsw commented out temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // m_ghibli3DLutUtil)
-  //	  m_ghibli3DLutUtil->onInit();
 }
 
 //-----------------------------------------------------------------------------
@@ -856,12 +846,14 @@ void SceneViewer::resizeGL(int w, int h) {
 
   if (m_previewMode != NO_PREVIEW) requestTimedRefresh();
 
+  // remake fbo with new size
+  if (LutCalibrator::instance()->isValid()) {
+    if (m_fbo) delete m_fbo;
+    m_fbo = new QOpenGLFramebufferObject(w, h);
+  }
+
   // for updating the navigator in levelstrip
   emit refreshNavi();
-  // iwsw commented out temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // m_ghibli3DLutUtil)
-  //	m_ghibli3DLutUtil->onResize(w, h);
 }
 
 //-----------------------------------------------------------------------------
@@ -1381,11 +1373,7 @@ void SceneViewer::paintGL() {
   time.start();
 #endif
 
-  // iwsw commented out temporarily
-  // if (!m_isPicking &&
-  //	Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // m_ghibli3DLutUtil)
-  //	m_ghibli3DLutUtil->startDraw();
+  if (!m_isPicking && LutCalibrator::instance()->isValid()) m_fbo->bind();
 
   if (m_hRuler && m_vRuler) {
     if (!viewRulerToggle.getStatus() &&
@@ -1415,11 +1403,8 @@ void SceneViewer::paintGL() {
     glPopMatrix();
     m_viewGrabImage->unlock();
 
-    // iwsw commented out temporarily
-    // if (!m_isPicking &&
-    //	Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-    // m_ghibli3DLutUtil)
-    //	m_ghibli3DLutUtil->endDraw();
+    if (!m_isPicking && LutCalibrator::instance()->isValid())
+      LutCalibrator::instance()->onEndDraw(m_fbo);
 
     return;
   }
@@ -1427,11 +1412,8 @@ void SceneViewer::paintGL() {
   drawBuildVars();
 
   check_framebuffer_status();
-  // iwsw commented out temporarily
-  // if (!m_isPicking &&
-  //	  !Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() ||
-  //! m_ghibli3DLutUtil)
   copyFrontBufferToBackBuffer();
+
   check_framebuffer_status();
   drawEnableScissor();
   check_framebuffer_status();
@@ -1465,11 +1447,8 @@ void SceneViewer::paintGL() {
 #endif
   // TOfflineGL::setContextManager(0);
 
-  // iwsw commented out temporarily
-  // if (!m_isPicking &&
-  //	Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  // m_ghibli3DLutUtil)
-  //	m_ghibli3DLutUtil->endDraw();
+  if (!m_isPicking && LutCalibrator::instance()->isValid())
+    LutCalibrator::instance()->onEndDraw(m_fbo);
 }
 
 //-----------------------------------------------------------------------------
@@ -2556,3 +2535,15 @@ TRectD SceneViewer::getGeometry() const {
 void SceneViewer::doDeleteSubCamera() {
   PreviewSubCameraManager::instance()->deleteSubCamera(this);
 }
+
+//-----------------------------------------------------------------------------
+
+void SceneViewer::bindFBO() {
+  if (m_fbo) m_fbo->bind();
+}
+
+//-----------------------------------------------------------------------------
+
+void SceneViewer::releaseFBO() {
+  if (m_fbo) m_fbo->release();
+}
diff --git a/toonz/sources/toonz/sceneviewer.h b/toonz/sources/toonz/sceneviewer.h
index 4b456b1..d5e6824 100644
--- a/toonz/sources/toonz/sceneviewer.h
+++ b/toonz/sources/toonz/sceneviewer.h
@@ -14,8 +14,6 @@
 #include "toonzqt/menubarcommand.h"
 #include "toonzqt/flipconsole.h"
 #include "toonzqt/glwidget_for_highdpi.h"
-// iwsw commented out temporarily
-//#include "toonzqt/ghibli_3dlut_util.h"
 
 // TnzTools includes
 #include "tools/tool.h"
@@ -36,6 +34,7 @@ class SceneViewer;
 class LocatorPopup;
 class QGestureEvent;
 class QTouchEvent;
+class QOpenGLFramebufferObject;
 
 namespace ImageUtils {
 class FullScreenWidget;
@@ -145,6 +144,9 @@ class SceneViewer final : public GLWidgetForHighDpi,
 
   bool m_editPreviewSubCamera;
 
+  // used for color calibration with 3DLUT
+  QOpenGLFramebufferObject *m_fbo = NULL;
+
   enum Device3D {
     NONE,
     SIDE_LEFT_3D,
@@ -160,8 +162,6 @@ class SceneViewer final : public GLWidgetForHighDpi,
 
   QMatrix4x4 m_projectionMatrix;
 
-  // iwsw commented out temporarily
-  // Ghibli3DLutUtil * m_ghibli3DLutUtil;
 public:
   // iwsw commented out temporarily
   // Ghibli3DLutUtil* get3DLutUtil(){ return m_ghibli3DLutUtil; }
@@ -262,6 +262,9 @@ public:
   double getVGuide(int index);
   double getHGuide(int index);
 
+  void bindFBO() override;
+  void releaseFBO() override;
+
 public:
   // SceneViewer's gadget public functions
   TPointD winToWorld(const QPointF &pos) const;
diff --git a/toonz/sources/toonzlib/preferences.cpp b/toonz/sources/toonzlib/preferences.cpp
index ed297d5..3eee622 100644
--- a/toonz/sources/toonzlib/preferences.cpp
+++ b/toonz/sources/toonzlib/preferences.cpp
@@ -666,6 +666,18 @@ Preferences::Preferences()
   m_loadedXsheetLayout = m_xsheetLayoutPreference;
 
   getValue(*m_settings, "currentTimelineEnabled", m_currentTimelineEnabled);
+
+  getValue(*m_settings, "colorCalibrationEnabled", m_colorCalibrationEnabled);
+  QVariant val = m_settings->value("colorCalibrationLutPaths");
+  if (val.canConvert<QVariantMap>()) {
+    QAssociativeIterable iterable           = val.value<QAssociativeIterable>();
+    QAssociativeIterable::const_iterator it = iterable.begin();
+    const QAssociativeIterable::const_iterator end = iterable.end();
+    for (; it != end; ++it) {
+      m_colorCalibrationLutPaths.insert(it.key().toString(),
+                                        it.value().toString());
+    }
+  }
 }
 
 //-----------------------------------------------------------------
@@ -1617,3 +1629,30 @@ void Preferences::enableCurrentTimelineIndicator(bool on) {
   m_currentTimelineEnabled = on;
   m_settings->setValue("currentTimelineEnabled", on ? "1" : "0");
 }
+
+//-----------------------------------------------------------------
+// color calibration using 3DLUT
+
+void Preferences::enableColorCalibration(bool on) {
+  m_colorCalibrationEnabled = on;
+  m_settings->setValue("colorCalibrationEnabled", on ? "1" : "0");
+}
+
+void Preferences::setColorCalibrationLutPath(QString monitorName,
+                                             QString path) {
+  m_colorCalibrationLutPaths.insert(monitorName, path);
+  QMap<QString, QVariant> map;
+  QMap<QString, QString>::const_iterator i =
+      m_colorCalibrationLutPaths.constBegin();
+  while (i != m_colorCalibrationLutPaths.constEnd()) {
+    map.insert(i.key(), i.value());
+    i++;
+  }
+  m_settings->setValue("colorCalibrationLutPaths", map);
+}
+
+QString Preferences::getColorCalibrationLutPath(QString &monitorName) const {
+  return m_colorCalibrationLutPaths.value(monitorName);
+}
+
+//-----------------------------------------------------------------
\ No newline at end of file
diff --git a/toonz/sources/toonzqt/CMakeLists.txt b/toonz/sources/toonzqt/CMakeLists.txt
index bed4735..513b5f1 100644
--- a/toonz/sources/toonzqt/CMakeLists.txt
+++ b/toonz/sources/toonzqt/CMakeLists.txt
@@ -87,6 +87,7 @@ set(MOC_HEADERS
     ../include/toonzqt/combohistogram.h
     ../include/toonzqt/fxiconmanager.h
     ../include/toonzqt/glwidget_for_highdpi.h
+    ../include/toonzqt/lutcalibrator.h
     pluginhost.h
 )
 
@@ -193,6 +194,7 @@ set(SOURCES
     plugin_param_view_interface.cpp
     plugin_ui_page_interface.cpp
     toonz_params.cpp
+	lutcalibrator.cpp
 )
 
 set(RESOURCES toonzqt.qrc)
diff --git a/toonz/sources/toonzqt/colorfield.cpp b/toonz/sources/toonzqt/colorfield.cpp
index a052eaa..3396785 100644
--- a/toonz/sources/toonzqt/colorfield.cpp
+++ b/toonz/sources/toonzqt/colorfield.cpp
@@ -9,6 +9,7 @@
 #include "tconvert.h"
 #include "tcolorstyles.h"
 #include "trop.h"
+#include "toonzqt/lutcalibrator.h"
 
 #include <QLayout>
 #include <QPainter>
@@ -95,9 +96,9 @@ void StyleSample::setStyle(TColorStyle &style) {
 */
 void StyleSample::setColor(const TPixel32 &pixel) {
   QColor color(pixel.r, pixel.g, pixel.b, pixel.m);
-  // iwsw commented out temporarily
-  // if (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-  //	Ghibli3DLutConverter::instance()->convert(color);
+  if (LutCalibrator::instance()->isValid())
+    LutCalibrator::instance()->convert(color);
+
   m_samplePixmap.fill(color.rgba());
   update();
 }
diff --git a/toonz/sources/toonzqt/combohistogram.cpp b/toonz/sources/toonzqt/combohistogram.cpp
index ecd3d2d..14f35e5 100644
--- a/toonz/sources/toonzqt/combohistogram.cpp
+++ b/toonz/sources/toonzqt/combohistogram.cpp
@@ -10,8 +10,7 @@
 #include <QString>
 
 #include "toonz/preferences.h"
-// iwsw commented out temporarily
-//#include "toonzqt/ghibli_3dlut_converter.h"
+#include "toonzqt/lutcalibrator.h"
 #include <QPushButton>
 #include <QDialog>
 
@@ -323,17 +322,12 @@ void ComboHistoRGBLabel::paintEvent(QPaintEvent *pe) {
     return;
   }
 
-  // iwsw commented out temporarily
-  /*
-  if(Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-  {
-          QColor convertedColor(m_color);
-          Ghibli3DLutConverter::instance()->convert(convertedColor);
-          p.setBrush(convertedColor);
-  }
-  else
-  */
-  p.setBrush(m_color);
+  if (LutCalibrator::instance()->isValid()) {
+    QColor convertedColor(m_color);
+    LutCalibrator::instance()->convert(convertedColor);
+    p.setBrush(convertedColor);
+  } else
+    p.setBrush(m_color);
 
   p.drawRect(bgRect);
 
diff --git a/toonz/sources/toonzqt/lutcalibrator.cpp b/toonz/sources/toonzqt/lutcalibrator.cpp
new file mode 100644
index 0000000..226f796
--- /dev/null
+++ b/toonz/sources/toonzqt/lutcalibrator.cpp
@@ -0,0 +1,589 @@
+#include "toonzqt/lutcalibrator.h"
+
+// Tnzlib includes
+#include "toonz/preferences.h"
+
+// TnzCore includes
+#include "tmsgcore.h"
+
+#include <QOpenGLShader>
+#include <QOpenGLShaderProgram>
+#include <QOpenGLFramebufferObject>
+#include <QOpenGLTexture>
+#include <QOpenGLContext>
+#include <QOffscreenSurface>
+#include <QFile>
+#include <QColor>
+
+namespace {
+inline bool execWarning(const QString& s) {
+  DVGui::MsgBox(DVGui::WARNING, s);
+  return false;
+}
+};
+
+#ifdef WIN32
+
+#include <QStringList>
+#include <QSettings>
+#include <QByteArray>
+
+namespace {
+// obtain monitor information from registry
+QStringList getMonitorNames() {
+  QStringList subPathSet;
+  // QSettings regSys("SYSTEM\\CurrentControlSet\\Enum\\DISPLAY",
+  // QSettings::NativeFormat);
+  QSettings regSys(
+      "HKEY_LOCAL_MACHINE\\SYSTEM\\CurrentControlSet\\Enum\\DISPLAY",
+      QSettings::NativeFormat);
+  QStringList children = regSys.childGroups();
+  // return value
+  QStringList nameList;
+
+  if (children.isEmpty()) {
+    std::cout << "getMonitorNames : Failed to Open Registry" << std::endl;
+    return nameList;
+  }
+
+  for (int c = 0; c < children.size(); c++) {
+    // Parent Key : DISPLAY
+    // Child Keys : AVO0000, ENC2174, etc.
+    // Grandchild Key : 5&388..
+    // Find grandchild key which contains a great-grandchild key named "Control"
+
+    regSys.beginGroup(children.at(c));  // Child keys : AVO0000, ENC2174, etc.
+    QStringList grandChildren = regSys.childGroups();
+    for (int gc = 0; gc < grandChildren.size(); gc++) {
+      regSys.beginGroup(grandChildren.at(gc));  // Grandchild key : 5&388..
+
+      QStringList greatGrandChildren = regSys.childGroups();
+
+      if (greatGrandChildren.contains(
+              "Control"))  // If the key "Control" is found
+      {
+        // Obtain variable "EDID" from the key "Device Parameters"
+        regSys.beginGroup("Device Parameters");
+
+        // the key may be not "EDID", but "BAD_EDID"
+        if (regSys.contains("EDID")) {
+          QString subPath = regSys.group().replace("/", "\\").prepend(
+              "SYSTEM\\CurrentControlSet\\Enum\\DISPLAY\\");
+          subPathSet.push_back(subPath);
+        }
+        regSys.endGroup();
+      }
+      regSys.endGroup();
+    }
+    // subPath may not be one...?
+    // if(!subPath.isEmpty())
+    //	break;
+    regSys.endGroup();
+  }
+
+  if (subPathSet.isEmpty()) {
+    std::cout << "getMonitorNames : Failed to Find Current EDID" << std::endl;
+    return nameList;
+  }
+
+  // for each subPath ( it may become more than one when using submonitor )
+  for (int sp = 0; sp < subPathSet.size(); sp++) {
+    QString subPath = subPathSet.at(sp);
+
+    HKEY handle = 0;
+
+    LONG res = RegOpenKeyExW(HKEY_LOCAL_MACHINE,
+                             reinterpret_cast<const wchar_t*>(subPath.utf16()),
+                             0, KEY_READ, &handle);
+
+    if (res == ERROR_SUCCESS && handle) {
+      QString keyStr("EDID");
+
+      // get the size and type of the value
+      DWORD dataType;
+      DWORD dataSize;
+      LONG res = RegQueryValueExW(
+          handle, reinterpret_cast<const wchar_t*>(keyStr.utf16()), 0,
+          &dataType, 0, &dataSize);
+
+      if (res != ERROR_SUCCESS) {
+        RegCloseKey(handle);
+        continue;
+      }
+
+      // get the value
+      QByteArray ba(dataSize, 0);
+      res = RegQueryValueExW(
+          handle, reinterpret_cast<const wchar_t*>(keyStr.utf16()), 0, 0,
+          reinterpret_cast<unsigned char*>(ba.data()), &dataSize);
+
+      if (res != ERROR_SUCCESS) {
+        RegCloseKey(handle);
+        continue;
+      }
+
+      QString s;
+      if (dataSize) {
+        s = QString::fromUtf16((const ushort*)ba.constData(), ba.size() / 2);
+      }
+
+      QString valStr;
+      QList<int> valArray;
+      for (int b = 0; b < s.length(); b++) {
+        QChar c1((int)s[b].unicode() % 256);
+        QChar c2((int)s[b].unicode() / 256);
+        valStr.append(c1.toLatin1());
+        valStr.append(c2.toLatin1());
+        valArray.append((int)s[b].unicode() % 256);
+        valArray.append((int)s[b].unicode() / 256);
+      }
+
+      // machine name starts from "FC 00", end with "0A"
+      int index1 = valArray.indexOf(252);         // FC
+      int index2 = valArray.indexOf(10, index1);  // 0A
+
+      if (index1 > 0 && index2 > 0) {
+        QString machineName = valStr.mid(index1 + 2, index2 - index1 - 2);
+        nameList.push_back(machineName);
+        // std::wcout << "machine name = " << machineName.toStdWString() <<
+        // std::endl;
+      }
+      RegCloseKey(handle);
+
+    } else {
+      std::cout << "getMonitorNames : failed to get handle" << std::endl;
+      continue;
+    }
+  }
+
+  if (nameList.isEmpty())
+    std::cout << "getMonitorNames : No Monitor Name Found" << std::endl;
+
+  return nameList;
+}
+};
+#endif
+
+//-----------------------------------------------------------------------------
+
+LutCalibrator* LutCalibrator::instance() {
+  static LutCalibrator _instance;
+  return &_instance;
+}
+
+//-----------------------------------------------------------------------------
+
+void LutCalibrator::initialize() {
+  static bool hasInitialized = false;
+  if (hasInitialized) return;
+  hasInitialized = true;
+
+  initializeOpenGLFunctions();
+
+  // check whether preference enables color calibration
+  if (!Preferences::instance()->isColorCalibrationEnabled()) return;
+
+  // obtain current monitor name
+  QString monitorName = getMonitorName();
+
+  // obtain 3dlut path associated to the monitor name
+  QString lutPath =
+      Preferences::instance()->getColorCalibrationLutPath(monitorName);
+
+  if (lutPath.isEmpty()) return;
+
+  // check existence of the 3dlut file
+  // load 3dlut data
+  if (!loadLutFile(lutPath)) return;
+
+  // create shader
+  if (!initializeLutTextureShader()) {
+    if (m_shader.program) delete m_shader.program;
+    if (m_shader.vert) delete m_shader.vert;
+    if (m_shader.frag) delete m_shader.frag;
+    return;
+  }
+  createViewerVBO();
+
+  // input 3dlut data to the shader
+  assignLutTexture();
+
+  m_isValid = true;
+  return;
+}
+
+//-----------------------------------------------------------------------------
+
+void LutCalibrator::finalize() {
+  if (!m_isValid) return;
+  // release shader
+  if (m_shader.program) delete m_shader.program;
+  if (m_shader.vert) delete m_shader.vert;
+  if (m_shader.frag) delete m_shader.frag;
+  // release VBO
+  if (m_viewerVBO.isCreated()) m_viewerVBO.destroy();
+  // release LUT texture
+  if (m_lut.tex && m_lut.tex->isCreated()) {
+    m_lut.tex->destroy();
+    delete m_lut.tex;
+  }
+  if (m_lut.data) delete[] m_lut.data;
+}
+
+//-----------------------------------------------------------------------------
+
+bool LutCalibrator::initializeLutTextureShader() {
+  m_shader.vert = new QOpenGLShader(QOpenGLShader::Vertex);
+  const char* simple_vsrc =
+      "#version 330 core\n"
+      "// Input vertex data, different for all executions of this shader.\n"
+      "layout(location = 0) in vec3 vertexPosition;\n"
+      "layout(location = 1) in vec2 texCoord;\n"
+      "// Output data ; will be interpolated for each fragment.\n"
+      "out vec2 UV;\n"
+      "// Values that stay constant for the whole mesh.\n"
+      "void main() {\n"
+      "  // Output position of the vertex, in clip space : MVP * position\n"
+      "  gl_Position = vec4(vertexPosition, 1);\n"
+      "  // UV of the vertex. No special space for this one.\n"
+      "  UV = texCoord;\n"
+      "}\n";
+  bool ret = m_shader.vert->compileSourceCode(simple_vsrc);
+  if (!ret)
+    return execWarning(
+        QObject::tr("Failed to compile m_textureShader.vert.", "gl"));
+
+  m_shader.frag = new QOpenGLShader(QOpenGLShader::Fragment);
+  const char* simple_fsrc =
+      "#version 330 core \n"
+      "// Interpolated values from the vertex shaders \n"
+      "in vec2 UV; \n"
+      "// Ouput data \n"
+      "out vec4 color; \n"
+      "// Values that stay constant for the whole mesh. \n"
+      "uniform sampler2D tex; \n"
+      "uniform sampler3D lut; \n"
+      "uniform vec3 lutSize; \n"
+      "void main() { \n"
+      "  vec3 rawColor = texture(tex,UV).rgb; \n"
+      "  vec3 scale = (lutSize - 1.0) / lutSize; \n"
+      "  vec3 offset = 1.0 / (2.0 * lutSize); \n"
+      "  color = vec4(texture(lut, scale * rawColor + offset).rgb, 1.0); \n"
+      "} \n";
+  ret = m_shader.frag->compileSourceCode(simple_fsrc);
+  if (!ret)
+    return execWarning(QObject::tr("Failed to compile m_shader.frag.", "gl"));
+
+  m_shader.program = new QOpenGLShaderProgram();
+  // add shaders
+  ret = m_shader.program->addShader(m_shader.vert);
+  if (!ret)
+    return execWarning(QObject::tr("Failed to add m_shader.vert.", "gl"));
+  ret = m_shader.program->addShader(m_shader.frag);
+  if (!ret)
+    return execWarning(QObject::tr("Failed to add m_shader.frag.", "gl"));
+  // link shaders
+  ret = m_shader.program->link();
+  if (!ret)
+    return execWarning(QObject::tr("Failed to link simple shader: %1", "gl")
+                           .arg(m_shader.program->log()));
+  // obtain parameter locations
+  m_shader.vertexAttrib = m_shader.program->attributeLocation("vertexPosition");
+  if (m_shader.vertexAttrib == -1)
+    return execWarning(
+        QObject::tr("Failed to get attribute location of %1", "gl")
+            .arg("vertexPosition"));
+  m_shader.texCoordAttrib = m_shader.program->attributeLocation("texCoord");
+  if (m_shader.texCoordAttrib == -1)
+    return execWarning(
+        QObject::tr("Failed to get attribute location of %1", "gl")
+            .arg("texCoord"));
+  m_shader.texUniform = m_shader.program->uniformLocation("tex");
+  if (m_shader.texUniform == -1)
+    return execWarning(
+        QObject::tr("Failed to get uniform location of %1", "gl").arg("tex"));
+  m_shader.lutUniform = m_shader.program->uniformLocation("lut");
+  if (m_shader.lutUniform == -1)
+    return execWarning(
+        QObject::tr("Failed to get uniform location of %1", "gl").arg("lut"));
+  m_shader.lutSizeUniform = m_shader.program->uniformLocation("lutSize");
+  if (m_shader.lutSizeUniform == -1)
+    return execWarning(QObject::tr("Failed to get uniform location of %1", "gl")
+                           .arg("lutSize"));
+
+  return true;
+}
+
+//-----------------------------------------------------------------------------
+
+void LutCalibrator::createViewerVBO() {
+  GLfloat vertex[]   = {-1.0f, -1.0f, 1.0f, -1.0f, 1.0f, 1.0f, -1.0f, 1.0f};
+  GLfloat texCoord[] = {0.0f, 0.0f, 1.0f, 0.0f, 1.0f, 1.0f, 0.0f, 1.0f};
+
+  m_viewerVBO.create();
+  m_viewerVBO.bind();
+  m_viewerVBO.allocate(4 * 4 * sizeof(GLfloat));
+  m_viewerVBO.write(0, vertex, sizeof(vertex));
+  m_viewerVBO.write(sizeof(vertex), texCoord, sizeof(texCoord));
+  m_viewerVBO.release();
+}
+
+//-----------------------------------------------------------------------------
+
+void LutCalibrator::onEndDraw(QOpenGLFramebufferObject* fbo) {
+  assert((glGetError()) == GL_NO_ERROR);
+  fbo->release();
+  GLuint textureId = fbo->texture();
+
+  glEnable(GL_TEXTURE_2D);
+  glActiveTexture(GL_TEXTURE4);
+  glBindTexture(GL_TEXTURE_2D, textureId);
+
+  glActiveTexture(GL_TEXTURE5);
+  m_lut.tex->bind();
+
+  glPushMatrix();
+  glLoadIdentity();
+
+  m_shader.program->bind();
+  m_shader.program->setUniformValue(m_shader.texUniform,
+                                    4);  // use texture unit 4
+  m_shader.program->setUniformValue(m_shader.lutUniform,
+                                    5);  // use texture unit 5
+  GLfloat size = (GLfloat)m_lut.meshSize;
+  m_shader.program->setUniformValue(m_shader.lutSizeUniform, size, size, size);
+
+  m_shader.program->enableAttributeArray(m_shader.vertexAttrib);
+  m_shader.program->enableAttributeArray(m_shader.texCoordAttrib);
+
+  m_viewerVBO.bind();
+  m_shader.program->setAttributeBuffer(m_shader.vertexAttrib, GL_FLOAT, 0, 2);
+  m_shader.program->setAttributeBuffer(m_shader.texCoordAttrib, GL_FLOAT,
+                                       4 * 2 * sizeof(GLfloat), 2);
+  m_viewerVBO.release();
+
+  glDrawArrays(GL_TRIANGLE_FAN, 0, 4);
+
+  m_shader.program->disableAttributeArray(m_shader.vertexAttrib);
+  m_shader.program->disableAttributeArray(m_shader.texCoordAttrib);
+
+  m_shader.program->release();
+
+  glPopMatrix();
+  glDisable(GL_TEXTURE_2D);
+
+  assert((glGetError()) == GL_NO_ERROR);
+}
+
+//-----------------------------------------------------------------------------
+
+QString& LutCalibrator::getMonitorName() const {
+  static QString monitorName;
+  if (!monitorName.isEmpty()) return monitorName;
+
+#ifdef WIN32
+  QStringList list = getMonitorNames();
+  if (list.isEmpty())
+    monitorName = "Any Monitor";  // this should not be translated
+  else
+    monitorName = list.at(0);  // for now only the first monitor is handled
+#else
+  monitorName = "Any Monitor";  // this should not be translated
+#endif
+
+  return monitorName;
+}
+
+//-----------------------------------------------------------------------------
+
+bool LutCalibrator::loadLutFile(const QString& fp) {
+  struct locals {
+    // skip empty or comment lines
+    static inline QString readDataLine(QTextStream& stream) {
+      while (1) {
+        if (stream.atEnd()) return QString();
+        QString ret = stream.readLine();
+        if (!ret.isEmpty() && ret[0] != QChar('#')) return ret;
+      }
+    }
+
+    static inline int lutCoords(int r, int g, int b, int meshSize) {
+      return b * meshSize * meshSize * 3 + g * meshSize * 3 + r * 3;
+    }
+  };
+
+  QFile file(fp);
+  if (!file.open(QIODevice::ReadOnly | QIODevice::Text))
+    return execWarning(QObject::tr("Failed to Open 3DLUT File."));
+
+  QTextStream stream(&file);
+  QString line;
+
+  //---- read the 3DLUT files
+
+  // The first line shoud start from "3DMESH" keyword (case sensitive)
+  line = locals::readDataLine(stream);
+  if (line != "3DMESH") {
+    file.close();
+    return execWarning(
+        QObject::tr("Failed to Load 3DLUT File.\nIt should start with "
+                    "\"3DMESH\" keyword."));
+  }
+
+  // The second line is "Mesh [Input bit depth] [Output bit depth]"
+  // "Mesh" is a keyword (case sensitive) 
+  line             = locals::readDataLine(stream);
+  QStringList list = line.split(" ");
+  if (list.size() != 3 || list.at(0) != "Mesh") {
+    file.close();
+    return execWarning(
+        QObject::tr("Failed to Load 3DLUT File.\nThe second line should be "
+                    "\"Mesh [Input bit depth] [Output bit depth]\""));
+  }
+
+  int inputBitDepth  = list.at(1).toInt();
+  int outputBitDepth = list.at(2).toInt();
+
+  m_lut.meshSize = (int)pow(2.0, inputBitDepth) + 1;
+
+  float maxValue = pow(2.0, outputBitDepth) - 1.0f;
+
+  // The third line is corrections of values at each LUT grid
+  line = locals::readDataLine(stream);
+  list = line.split(" ", QString::SkipEmptyParts);
+  if (list.size() != m_lut.meshSize) {
+    file.close();
+    return execWarning(QObject::tr("Failed to Load 3DLUT File."));
+  }
+
+  m_lut.data = new float[m_lut.meshSize * m_lut.meshSize * m_lut.meshSize * 3];
+
+  for (int k = 0; k < m_lut.meshSize; ++k)  // r
+  {
+    for (int j = 0; j < m_lut.meshSize; ++j)  // g
+    {
+      for (int i = 0; i < m_lut.meshSize; ++i)  // b
+      {
+        line = locals::readDataLine(stream);
+        list = line.split(" ", QString::SkipEmptyParts);
+        if (list.size() != 3) {
+          file.close();
+          delete[] m_lut.data;
+          return execWarning(QObject::tr("Failed to Load 3DLUT File."));
+        }
+        float* lut = m_lut.data + locals::lutCoords(k, j, i, m_lut.meshSize);
+        *lut       = (float)(list.at(0).toInt()) / maxValue;
+        lut++;
+        *lut = (float)(list.at(1).toInt()) / maxValue;
+        lut++;
+        *lut = (float)(list.at(2).toInt()) / maxValue;
+      }
+    }
+  }
+
+  file.close();
+  return true;
+}
+
+//-----------------------------------------------------------------------------
+
+void LutCalibrator::assignLutTexture() {
+  assert(glGetError() == GL_NO_ERROR);
+
+  m_lut.tex = new QOpenGLTexture(QOpenGLTexture::Target3D);
+  m_lut.tex->setSize(m_lut.meshSize, m_lut.meshSize, m_lut.meshSize);
+  m_lut.tex->setFormat(QOpenGLTexture::RGB32F);
+  m_lut.tex->setLayers(1);
+  m_lut.tex->setMipLevels(1);
+  m_lut.tex->allocateStorage();
+  m_lut.tex->setMinMagFilters(QOpenGLTexture::Linear, QOpenGLTexture::Linear);
+  m_lut.tex->setWrapMode(QOpenGLTexture::ClampToEdge);
+
+  m_lut.tex->setData(QOpenGLTexture::RGB, QOpenGLTexture::Float32, m_lut.data);
+
+  assert(glGetError() == GL_NO_ERROR);
+}
+
+//-----------------------------------------------------------------------------
+
+// input : 0-1
+void LutCalibrator::convert(float& r, float& g, float& b) {
+  struct locals {
+    static inline float lerp(float val1, float val2, float ratio) {
+      return val1 * (1.0f - ratio) + val2 * ratio;
+    }
+    static inline int getCoord(int r, int g, int b, int meshSize) {
+      return b * meshSize * meshSize * 3 + g * meshSize * 3 + r * 3;
+    }
+  };
+
+  if (!m_isValid) return;
+
+  float ratio[3];   // RGB軸
+  int index[3][2];  // rgb インデックス
+  float rawVal[3] = {r, g, b};
+
+  float vertex_color[2][2][2][3];  //補間用の１ボクセルの頂点色
+
+  for (int c = 0; c < 3; c++) {
+    float val   = rawVal[c] * (float)(m_lut.meshSize - 1);
+    index[c][0] = (int)val;
+    // boundary condition: if rawVal == 1 the value will not be interporated
+    index[c][1] = (rawVal[c] >= 1.0f) ? index[c][0] : index[c][0] + 1;
+    ratio[c]    = val - (float)index[c][0];
+  }
+
+  for (int rr = 0; rr < 2; rr++)
+    for (int gg = 0; gg < 2; gg++)
+      for (int bb = 0; bb < 2; bb++) {
+        float* val = &m_lut.data[locals::getCoord(
+            index[0][rr], index[1][gg], index[2][bb], m_lut.meshSize)];
+        for (int chan                    = 0; chan < 3; chan++, val++)
+          vertex_color[rr][gg][bb][chan] = *val;
+      }
+  float result[3];
+
+  for (int chan = 0; chan < 3; chan++) {
+    result[chan] = locals::lerp(
+        locals::lerp(locals::lerp(vertex_color[0][0][0][chan],
+                                  vertex_color[0][0][1][chan], ratio[2]),
+                     locals::lerp(vertex_color[0][1][0][chan],
+                                  vertex_color[0][1][1][chan], ratio[2]),
+                     ratio[1]),
+        locals::lerp(locals::lerp(vertex_color[1][0][0][chan],
+                                  vertex_color[1][0][1][chan], ratio[2]),
+                     locals::lerp(vertex_color[1][1][0][chan],
+                                  vertex_color[1][1][1][chan], ratio[2]),
+                     ratio[1]),
+        ratio[0]);
+  }
+
+  r = result[0];
+  g = result[1];
+  b = result[2];
+}
+
+//-----------------------------------------------------------------------------
+
+void LutCalibrator::convert(QColor& col) {
+  if (!m_isValid) return;
+  float r = col.redF();
+  float g = col.greenF();
+  float b = col.blueF();
+  convert(r, g, b);
+  // 0.5 offset is necessary for converting to 255 grading
+  col = QColor((int)(r * 255.0 + 0.5), (int)(g * 255.0 + 0.5),
+               (int)(b * 255.0 + 0.5), col.alpha());
+}
+
+//-----------------------------------------------------------------------------
+
+void LutCalibrator::convert(TPixel32& col) {
+  if (!m_isValid) return;
+  float r = (float)col.r / 255.0;
+  float g = (float)col.g / 255.0;
+  float b = (float)col.b / 255.0;
+  convert(r, g, b);
+  col = TPixel32((int)(r * 255.0 + 0.5), (int)(g * 255.0 + 0.5),
+                 (int)(b * 255.0 + 0.5), col.m);
+}
\ No newline at end of file
diff --git a/toonz/sources/toonzqt/paletteviewergui.cpp b/toonz/sources/toonzqt/paletteviewergui.cpp
index 7b20ad9..8ee8126 100644
--- a/toonz/sources/toonzqt/paletteviewergui.cpp
+++ b/toonz/sources/toonzqt/paletteviewergui.cpp
@@ -11,6 +11,7 @@
 #include "toonzqt/stylenameeditor.h"
 #include "toonzqt/viewcommandids.h"
 #include "palettedata.h"
+#include "toonzqt/lutcalibrator.h"
 
 // TnzLib includes
 #include "toonz/palettecmd.h"
@@ -681,10 +682,8 @@ void PageViewer::paintEvent(QPaintEvent *e) {
       // and TBlackCleanupStyle(2002)
       if (style->getTagId() == 3 || style->getTagId() == 2001 ||
           style->getTagId() == 2002) {
-        // iwsw commented out temporaly
-        // if
-        // (Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled())
-        //	Ghibli3DLutConverter::instance()->convert(styleColor);
+        if (LutCalibrator::instance()->isValid())
+          LutCalibrator::instance()->convert(styleColor);
 
         p.fillRect(chipRect, QBrush(styleColor));
 
diff --git a/toonz/sources/toonzqt/styleeditor.cpp b/toonz/sources/toonzqt/styleeditor.cpp
index 8950103..ee430ab 100644
--- a/toonz/sources/toonzqt/styleeditor.cpp
+++ b/toonz/sources/toonzqt/styleeditor.cpp
@@ -6,6 +6,7 @@
 #include "toonzqt/gutil.h"
 #include "toonzqt/filefield.h"
 #include "historytypes.h"
+#include "toonzqt/lutcalibrator.h"
 
 // TnzLib includes
 #include "toonz/txshlevel.h"
@@ -53,6 +54,7 @@
 #include <QStyleOptionSlider>
 #include <QToolTip>
 #include <QSplitter>
+#include <QOpenGLFramebufferObject>
 
 using namespace StyleEditorGUI;
 
@@ -557,44 +559,24 @@ HexagonalColorWheel::HexagonalColorWheel(QWidget *parent)
   setSizePolicy(QSizePolicy::Expanding, QSizePolicy::Expanding);
   setFocusPolicy(Qt::NoFocus);
   m_currentWheel = none;
-
-  // iwsw commented out temporarily
-  /*
-  if(Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  Ghibli3DLutUtil::m_isValid)
-  {
-  m_ghibli3DLutUtil = new Ghibli3DLutUtil();
-  m_ghibli3DLutUtil->setInvert();
-  }
-  */
 }
 
 //-----------------------------------------------------------------------------
 
 HexagonalColorWheel::~HexagonalColorWheel() {
-  // iwsw commented out temporarily
-  /*
-  if(m_ghibli3DLutUtil)
-  {
-  m_ghibli3DLutUtil->onEnd();
-  delete m_ghibli3DLutUtil;
-  }
-  */
+  if (m_fbo) delete m_fbo;
 }
 
 //-----------------------------------------------------------------------------
 
 void HexagonalColorWheel::initializeGL() {
   initializeOpenGLFunctions();
+
+  // to be computed once through the software
+  LutCalibrator::instance()->initialize();
+
   QColor const color = getBGColor();
   glClearColor(color.redF(), color.greenF(), color.blueF(), color.alphaF());
-
-  // iwsw commented out temporarily
-  /*
-  if(Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  m_ghibli3DLutUtil)
-  m_ghibli3DLutUtil->onInit();
-  */
 }
 
 //-----------------------------------------------------------------------------
@@ -646,12 +628,11 @@ void HexagonalColorWheel::resizeGL(int w, int h) {
   glLoadIdentity();
   glOrtho(0.0, (GLdouble)w, (GLdouble)h, 0.0, 1.0, -1.0);
 
-  // iwsw commented out temporarily
-  /*
-  if(Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  m_ghibli3DLutUtil)
-  m_ghibli3DLutUtil->onResize(w,h);
-  */
+  // remake fbo with new size
+  if (LutCalibrator::instance()->isValid()) {
+    if (m_fbo) delete m_fbo;
+    m_fbo = new QOpenGLFramebufferObject(w, h);
+  }
 }
 
 //-----------------------------------------------------------------------------
@@ -664,12 +645,7 @@ void HexagonalColorWheel::paintGL() {
 
   glMatrixMode(GL_MODELVIEW);
 
-  // iwsw commented out temporarily
-  /*
-  if(Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  m_ghibli3DLutUtil)
-  m_ghibli3DLutUtil->startDraw();
-  */
+  if (LutCalibrator::instance()->isValid()) m_fbo->bind();
 
   glClear(GL_COLOR_BUFFER_BIT);
 
@@ -716,12 +692,8 @@ void HexagonalColorWheel::paintGL() {
 
   glPopMatrix();
 
-  // iwsw commented out temporarily
-  /*
-  if(Preferences::instance()->isDoColorCorrectionByUsing3DLutEnabled() &&
-  m_ghibli3DLutUtil)
-  m_ghibli3DLutUtil->endDraw();
-  */
+  if (LutCalibrator::instance()->isValid())
+    LutCalibrator::instance()->onEndDraw(m_fbo);
 }
 
 //-----------------------------------------------------------------------------