diff --git a/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.cpp b/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.cpp
index a752782207..6533d2e726 100644
--- a/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.cpp
+++ b/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.cpp
@@ -1,129 +1,129 @@
 /*============================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center (DKFZ)
 All rights reserved.
 
 Use of this source code is governed by a 3-clause BSD license that can be
 found in the LICENSE file.
 
 ============================================================================*/
 
 #include "QmitkOtsuTool3DGUI.h"
 #include "mitkOtsuTool3D.h"
 
 #include <QMessageBox>
 
 MITK_TOOL_GUI_MACRO(MITKSEGMENTATIONUI_EXPORT, QmitkOtsuTool3DGUI, "")
 
 QmitkOtsuTool3DGUI::QmitkOtsuTool3DGUI() : QmitkAutoMLSegmentationToolGUIBase()
 {
 }
 
 void QmitkOtsuTool3DGUI::ConnectNewTool(mitk::AutoSegmentationWithPreviewTool* newTool)
 {
   Superclass::ConnectNewTool(newTool);
 
   newTool->IsTimePointChangeAwareOff();
   m_FirstPreviewComputation = true;
 }
 
 void QmitkOtsuTool3DGUI::InitializeUI(QBoxLayout* mainLayout)
 {
   m_Controls.setupUi(this);
   mainLayout->addLayout(m_Controls.verticalLayout);
 
   connect(m_Controls.previewButton, SIGNAL(clicked()), this, SLOT(OnPreviewBtnClicked()));
   connect(m_Controls.m_Spinbox, SIGNAL(valueChanged(int)), this, SLOT(OnRegionSpinboxChanged(int)));
   connect(m_Controls.advancedSettingsButton, SIGNAL(toggled(bool)), this, SLOT(OnAdvancedSettingsButtonToggled(bool)));
 
   this->OnAdvancedSettingsButtonToggled(false);
 
   Superclass::InitializeUI(mainLayout);
 }
 
 void QmitkOtsuTool3DGUI::OnRegionSpinboxChanged(int numberOfRegions)
 {
   // we have to change to minimum number of histogram bins accordingly
   int curBinValue = m_Controls.m_BinsSpinBox->value();
   if (curBinValue < numberOfRegions)
     m_Controls.m_BinsSpinBox->setValue(numberOfRegions);
 }
 
 void QmitkOtsuTool3DGUI::OnAdvancedSettingsButtonToggled(bool toggled)
 {
   m_Controls.m_ValleyCheckbox->setVisible(toggled);
   m_Controls.binLabel->setVisible(toggled);
   m_Controls.m_BinsSpinBox->setVisible(toggled);
 
   auto tool = this->GetConnectedToolAs<mitk::OtsuTool3D>();
   if (toggled && nullptr != tool)
   {
     int max = tool->GetMaxNumberOfBins();
     if (max >= m_Controls.m_BinsSpinBox->minimum())
     {
       m_Controls.m_BinsSpinBox->setMaximum(max);
     }
   }
 }
 
 void QmitkOtsuTool3DGUI::OnPreviewBtnClicked()
 {
   auto tool = this->GetConnectedToolAs<mitk::OtsuTool3D>();
   if (nullptr != tool)
   {
-    if (!m_FirstPreviewComputation ||
+    if (!m_FirstPreviewComputation &&
       (tool->GetNumberOfRegions() == static_cast<unsigned int>(m_Controls.m_Spinbox->value()) &&
       tool->GetUseValley() == m_Controls.m_ValleyCheckbox->isChecked() &&
       tool->GetNumberOfBins() == static_cast<unsigned int>(m_Controls.m_BinsSpinBox->value())))
       return;
 
     m_FirstPreviewComputation = false;
 
     try
     {
       int proceed;
       QMessageBox *messageBox = new QMessageBox(QMessageBox::Question,
                                                 nullptr,
                                                 "The otsu segmentation computation may take several minutes depending "
                                                 "on the number of Regions you selected. Proceed anyway?",
                                                 QMessageBox::Ok | QMessageBox::Cancel);
       if (m_Controls.m_Spinbox->value() >= 5)
       {
         proceed = messageBox->exec();
         if (proceed != QMessageBox::Ok)
           return;
       }
 
       tool->SetNumberOfRegions(static_cast<unsigned int>(m_Controls.m_Spinbox->value()));
       tool->SetUseValley(m_Controls.m_ValleyCheckbox->isChecked());
       tool->SetNumberOfBins(static_cast<unsigned int>(m_Controls.m_BinsSpinBox->value()));
 
       tool->UpdatePreview();
     }
     catch (...)
     {
       this->setCursor(Qt::ArrowCursor);
       QMessageBox *messageBox =
         new QMessageBox(QMessageBox::Critical,
                         nullptr,
                         "itkOtsuFilter error: image dimension must be in {2, 3} and no RGB images can be handled.");
       messageBox->exec();
       delete messageBox;
       return;
     }
 
     this->SetLabelSetPreview(tool->GetMLPreview());
     tool->IsTimePointChangeAwareOn();
   }
 }
 
 void QmitkOtsuTool3DGUI::EnableWidgets(bool enabled)
 {
   Superclass::EnableWidgets(enabled);
   m_Controls.m_ValleyCheckbox->setEnabled(enabled);
   m_Controls.binLabel->setEnabled(enabled);
   m_Controls.m_BinsSpinBox->setEnabled(enabled);
   m_Controls.previewButton->setEnabled(enabled);
 }