diff --git a/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.cpp b/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.cpp
index e4d6db1064..3ad4067cf2 100644
--- a/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.cpp
+++ b/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.cpp
@@ -1,165 +1,173 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 #include "QmitkOtsuTool3DGUI.h"
 #include "QmitkConfirmSegmentationDialog.h"
 
 #include <qlabel.h>
 #include <qspinbox.h>
 #include <qpushbutton.h>
 #include <qlayout.h>
 #include <qlistwidget.h>
 #include <QMessageBox>
 
 MITK_TOOL_GUI_MACRO(MitkSegmentationUI_EXPORT, QmitkOtsuTool3DGUI, "")
 
 QmitkOtsuTool3DGUI::QmitkOtsuTool3DGUI()
 :QmitkToolGUI(),
 m_NumberOfRegions(0)
 {
   m_Controls.setupUi(this);
 
   connect( m_Controls.previewButton, SIGNAL(clicked()), this, SLOT(OnSpinboxValueAccept()));
   connect(m_Controls.m_selectionListWidget, SIGNAL(itemSelectionChanged()),
-          this, SLOT(OnItemSelectionChanged()));
+          this, SLOT(OnRegionSelectionChanged()));
+  connect( m_Controls.m_Spinbox, SIGNAL(valueChanged(int)), this, SLOT(OnRegionSpinboxChanged(int)) );
   connect( m_Controls.m_ConfSegButton, SIGNAL(clicked()), this, SLOT(OnSegmentationRegionAccept()));
   connect( this, SIGNAL(NewToolAssociated(mitk::Tool*)), this, SLOT(OnNewToolAssociated(mitk::Tool*)) );
   connect(m_Controls.advancedSettingsButton, SIGNAL(toggled(bool)), this, SLOT(OnAdvancedSettingsButtonToggled(bool)));
 
   this->OnAdvancedSettingsButtonToggled(false);
 }
 
 QmitkOtsuTool3DGUI::~QmitkOtsuTool3DGUI()
 {
 
 }
 
-void QmitkOtsuTool3DGUI::OnItemSelectionChanged()
+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::OnRegionSelectionChanged()
 {
   m_SelectedItems = m_Controls.m_selectionListWidget->selectedItems();
 
   if (m_SelectedItems.size() == 0)
   {
     m_Controls.m_ConfSegButton->setEnabled( false );
     m_OtsuTool3DTool->ShowMultiLabelResultNode(true);
     return;
   }
 
   if (m_OtsuTool3DTool.IsNotNull())
   {
     // update preview of region
     QList<QListWidgetItem *>::Iterator it;
     std::vector<int> regionIDs;
     for (it = m_SelectedItems.begin(); it != m_SelectedItems.end(); ++it)
       regionIDs.push_back((*it)->text().toInt());
     m_OtsuTool3DTool->UpdateBinaryPreview(regionIDs);
     m_Controls.m_ConfSegButton->setEnabled( true );
   }
 }
 
 void QmitkOtsuTool3DGUI::OnAdvancedSettingsButtonToggled(bool toggled)
 {
   m_Controls.m_ValleyCheckbox->setVisible(toggled);
   m_Controls.binLabel->setVisible(toggled);
   m_Controls.m_BinsSpinBox->setVisible(toggled);
 }
 
 void QmitkOtsuTool3DGUI::OnNewToolAssociated(mitk::Tool* tool)
 {
   m_OtsuTool3DTool = dynamic_cast<mitk::OtsuTool3D*>( tool );
 }
 
 void QmitkOtsuTool3DGUI::OnSegmentationRegionAccept()
 {
   QmitkConfirmSegmentationDialog dialog;
   QString segName = QString::fromStdString(m_OtsuTool3DTool->GetCurrentSegmentationName());
 
   dialog.SetSegmentationName(segName);
   int result = dialog.exec();
 
   switch(result)
   {
   case QmitkConfirmSegmentationDialog::CREATE_NEW_SEGMENTATION:
     m_OtsuTool3DTool->SetOverwriteExistingSegmentation(false);
     break;
   case QmitkConfirmSegmentationDialog::OVERWRITE_SEGMENTATION:
     m_OtsuTool3DTool->SetOverwriteExistingSegmentation(true);
     break;
   case QmitkConfirmSegmentationDialog::CANCEL_SEGMENTATION:
     return;
   }
 
   if (m_OtsuTool3DTool.IsNotNull() && m_Controls.m_selectionListWidget->currentItem() != NULL)
   {
     m_OtsuTool3DTool->ConfirmSegmentation();
   }
 }
 
 void QmitkOtsuTool3DGUI::OnSpinboxValueAccept()
 {
   if( m_NumberOfRegions == m_Controls.m_Spinbox->value() &&
     m_UseValleyEmphasis == m_Controls.m_ValleyCheckbox->isChecked() &&
     m_NumberOfBins == m_Controls.m_BinsSpinBox->value() )
     return;
 
   if (m_OtsuTool3DTool.IsNotNull())
   {
     try
     {
       m_NumberOfRegions = m_Controls.m_Spinbox->value();
       m_UseValleyEmphasis = m_Controls.m_ValleyCheckbox->isChecked();
       m_NumberOfBins = m_Controls.m_BinsSpinBox->value();
       int proceed;
 
       QMessageBox* messageBox = new QMessageBox(QMessageBox::Question, NULL, "The otsu segmentation computation may take several minutes depending on the number of Regions you selected. Proceed anyway?", QMessageBox::Ok | QMessageBox::Cancel);
       if (m_NumberOfRegions >= 5)
       {
         proceed = messageBox->exec();
         if (proceed != QMessageBox::Ok) return;
       }
       this->setCursor(Qt::WaitCursor);
       m_OtsuTool3DTool->RunSegmentation( m_NumberOfRegions, m_UseValleyEmphasis, m_NumberOfBins );
       this->setCursor(Qt::ArrowCursor);
     }
     catch( ... )
     {
       this->setCursor(Qt::ArrowCursor);
       QMessageBox* messageBox = new QMessageBox(QMessageBox::Critical, NULL, "itkOtsuFilter error: image dimension must be in {2, 3} and no RGB images can be handled.");
       messageBox->exec();
       delete messageBox;
       return;
     }
     //insert regions into widget
     QString itemName;
     QListWidgetItem* item;
     m_Controls.m_selectionListWidget->clear();
     for(int i=0; i<m_Controls.m_Spinbox->value(); ++i)
     {
       itemName = QString::number(i);
       item = new QListWidgetItem(itemName);
       m_Controls.m_selectionListWidget->addItem(item);
     }
     //deactivate 'confirm segmentation'-button
     m_Controls.m_ConfSegButton->setEnabled(false);
   }
 }
 
 void QmitkOtsuTool3DGUI::OnVolumePreviewChecked(int state)
 {
   if (state == 1)
   {
   }
 }
diff --git a/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.h b/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.h
index c855b7dd7f..c6126cd698 100644
--- a/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.h
+++ b/Modules/SegmentationUI/Qmitk/QmitkOtsuTool3DGUI.h
@@ -1,86 +1,88 @@
 /*===================================================================
 
 The Medical Imaging Interaction Toolkit (MITK)
 
 Copyright (c) German Cancer Research Center,
 Division of Medical and Biological Informatics.
 All rights reserved.
 
 This software is distributed WITHOUT ANY WARRANTY; without
 even the implied warranty of MERCHANTABILITY or FITNESS FOR
 A PARTICULAR PURPOSE.
 
 See LICENSE.txt or http://www.mitk.org for details.
 
 ===================================================================*/
 
 #ifndef QmitkOtsuTool3DGUI_h_Included
 #define QmitkOtsuTool3DGUI_h_Included
 
 #include "QmitkToolGUI.h"
 #include <MitkSegmentationUIExports.h>
 #include "mitkOtsuTool3D.h"
 #include <QListWidget>
 #include <QPushButton>
 #include "ui_QmitkOtsuToolWidgetControls.h"
 
 class QSpinBox;
 class QLabel;
 
 /**
   \ingroup org_mitk_gui_qt_interactivesegmentation_internal
   \brief GUI for mitk::.
   \sa mitk::
 
   This GUI shows ...
 
   Last contributor: $Author$
 */
 class MitkSegmentationUI_EXPORT QmitkOtsuTool3DGUI : public QmitkToolGUI
 {
   Q_OBJECT
 
   public:
     mitkClassMacro(QmitkOtsuTool3DGUI, QmitkToolGUI);
     itkFactorylessNewMacro(Self)
     itkCloneMacro(Self)
 
   signals:
 
   public slots:
 
   protected slots:
 
     void OnNewToolAssociated(mitk::Tool*);
 
     void OnSpinboxValueAccept();
 
     void OnSegmentationRegionAccept();
 
-    void OnItemSelectionChanged();
+    void OnRegionSelectionChanged();
+
+    void OnRegionSpinboxChanged(int);
 
     void OnVolumePreviewChecked(int);
 
   private slots:
 
     void OnAdvancedSettingsButtonToggled(bool toggled);
 
   protected:
 
     QmitkOtsuTool3DGUI();
     virtual ~QmitkOtsuTool3DGUI();
 
     mitk::OtsuTool3D::Pointer m_OtsuTool3DTool;
 
     Ui_QmitkOtsuToolWidgetControls m_Controls;
 
     int m_NumberOfRegions;
 
     bool m_UseValleyEmphasis;
 
     int m_NumberOfBins;
 
     QList<QListWidgetItem *> m_SelectedItems;
 };
 
 #endif