Index: mitk/Core/Code/Rendering/mitkImageMapperGL2D.cpp
===================================================================
--- mitk/Core/Code/Rendering/mitkImageMapperGL2D.cpp	(revision 26476)
+++ mitk/Core/Code/Rendering/mitkImageMapperGL2D.cpp	(working copy)
@@ -938,6 +938,7 @@
   rendererInfo.m_TextureInterpolation = textureInterpolation;
 
   mitk::LevelWindow levelWindow;
+  mitk::LevelWindow opacLevelWindow;
 
   bool binary = false;
   this->GetDataNode()->GetBoolProperty( "binary", binary, renderer );
@@ -946,6 +947,7 @@
   {
    
     image->setExtrema(0, 1);
+    image->setOpacityExtrema( 0.0, 255.0 );
     image->setBinary(true);
 
     bool binaryOutline = false;
@@ -977,7 +979,17 @@
       this->GetLevelWindow( levelWindow, renderer );
     }
 
-    image->setExtrema( levelWindow.GetLowerWindowBound(), levelWindow.GetUpperWindowBound() ); 
+    image->setExtrema( levelWindow.GetLowerWindowBound(), levelWindow.GetUpperWindowBound() );
+
+    // obtain opacity level window
+    if( this->GetLevelWindow( opacLevelWindow, renderer, "opaclevelwindow" ) )
+    {
+      image->setOpacityExtrema( opacLevelWindow.GetLowerWindowBound(), opacLevelWindow.GetUpperWindowBound() );
+    }
+    else
+    {
+      image->setOpacityExtrema( 0.0, 255.0 );
+    }
   }
 
   bool useColor = false;
Index: mitk/Utilities/IIL4MITK/picimage.cpp
===================================================================
--- mitk/Utilities/IIL4MITK/picimage.cpp	(revision 26476)
+++ mitk/Utilities/IIL4MITK/picimage.cpp	(working copy)
@@ -72,6 +72,49 @@
 }
 
 void
+    iil4mitkPicImage::setOpacityExtrema (const float minimum, const float maximum)
+{
+  // assert (minimum < maximum);
+
+  _minOpac = minimum;
+  _maxOpac = maximum;
+  invalidateTextures ();
+}
+
+void
+iil4mitkPicImage::setOpacityWindow (const float level, const float window)
+{
+    // assert (window > 0);
+    _minOpac = level - window / 2.0;
+    _maxOpac = _minOpac + window;
+    invalidateTextures ();
+}
+
+float
+iil4mitkPicImage::minimumOpacity () const
+{
+    return _minOpac;
+}
+
+float
+iil4mitkPicImage::maximumOpacity () const
+{
+    return _maxOpac;
+}
+
+float
+iil4mitkPicImage::levelOpacity () const
+{
+    return (_minOpac + _maxOpac) / 2.0;
+}
+
+float
+iil4mitkPicImage::windowOpacity () const
+{
+    return (_maxOpac - _minOpac);
+}
+
+void
 iil4mitkPicImage::setColors (const unsigned char* colors)
 {
     _colors = colors;
@@ -147,6 +190,7 @@
 {
     _pic = NULL;
     _min = _max = 0.0;
+    _minOpac = _maxOpac = 0.0;
     _colors = NULL;
     _binary = false;
     _mask = false; 
@@ -417,6 +461,8 @@
     unsigned int slice = _pic->n[0] * _pic->n[1] * (_pic->bpe / 8);
     float scale = (_max -_min > 0 ? 255.0 / (_max - _min) : 0.0);
     float bias = _min * scale;
+    float scaleOpac = (_maxOpac -_minOpac > 0 ? 255.0 / (_maxOpac - _minOpac) : 0.0);
+    float biasOpac = _minOpac * scaleOpac;
     unsigned char *src = (unsigned char *) _pic->data + (y * _pic->n[0] + x) * (_pic->bpe/8);
     unsigned char *dst = data + (yoffset * width + xoffset) * (bpe () / 8);
     unsigned char *eol = dst + w * (bpe () / 8);
@@ -464,24 +510,30 @@
       unsigned char* dest = dst;
       while (dest < eol) 
       {
-        if(_min!=0 || _max!=255)
+        if(_min!=0 || _max!=255 || _minOpac!=0 || _maxOpac!=255)
         {
+          double rgb[3], alpha, hsi[3];
+
           // level/window mechanism for intensity in HSI space
-          double rgb[3], hsi[3];
           rgb[0] = source[0];
           rgb[1] = source[1];
           rgb[2] = source[2];
+          alpha  = source[3];
           RGBtoHSI<double>(rgb,hsi);
           hsi[2] = hsi[2] * 255.0 * scale - bias;
           hsi[2] = (hsi[2] > 255.0 ? 255 : (hsi[2] < 0.0 ? 0 : hsi[2]));
           hsi[2] /= 255.0;
           HSItoRGB<double>(hsi,rgb);
+
+          // level/window mechanism for opacity
+          alpha = alpha * scaleOpac - biasOpac;
+          alpha = (alpha > 255.0 ? 255 : (alpha < 0.0 ? 0 : alpha));
+
           dest[0] = (unsigned char)rgb[0];
           dest[1] = (unsigned char)rgb[1];
           dest[2] = (unsigned char)rgb[2];
+          dest[3] = (unsigned char)alpha;
 
-          dest[3] = source[3];
-
           source+=4;
           dest+=4;
         }
Index: mitk/Utilities/IIL4MITK/picimage.h
===================================================================
--- mitk/Utilities/IIL4MITK/picimage.h	(revision 26476)
+++ mitk/Utilities/IIL4MITK/picimage.h	(working copy)
@@ -45,7 +45,7 @@
     /*!
     \brief Sets the range of the intensities which will be displayed.
     @param level the level of the window
-    @param window the width of the window 
+    @param window the width of the window
     */
     void setWindow (const float level, const float window);
 
@@ -60,18 +60,54 @@
     float maximum () const;
 
     /*!
-    \brief Gets the level of the window which limits the 
+    \brief Gets the level of the window which limits the
     displayed intensities.
     */
     float level () const;
 
     /*!
-    \brief Gets the width of the window which limits the 
+    \brief Gets the width of the window which limits the
     displayed intensities.
     */
     float window () const;
 
     /*!
+    \brief Sets the range of opacity values which will be displayed.
+    @param minimum the minimal opacity
+    @param maximum the maximal opacity
+    */
+    void setOpacityExtrema (const float minimum, const float maximum);
+
+    /*!
+    \brief Sets the range of the opacities which will be displayed.
+    @param level the level of the window
+    @param window the width of the window
+    */
+    void setOpacityWindow (const float level, const float window);
+
+    /*!
+    \brief Gets the minimal opacity which will be displayed.
+    */
+    float minimumOpacity () const;
+
+    /*!
+    \brief Gets the maximal opacity which will be displayed.
+    */
+    float maximumOpacity () const;
+
+    /*!
+    \brief Gets the level of the window which limits the
+    displayed opacities.
+    */
+    float levelOpacity () const;
+
+    /*!
+    \brief Gets the width of the window which limits the
+    displayed opacities.
+    */
+    float windowOpacity () const;
+
+    /*!
     \brief Sets the color map which assigns each intensity
     a color according to the color model.
     @param colors the array of colors using either the
@@ -153,6 +189,11 @@
     float _min, _max;
 
     /*!
+    \brief The extremal opacity values.
+    */
+    float _minOpac, _maxOpac;
+
+    /*!
     \brief The color map.
     */
     const unsigned char* _colors;