Introduced ImageLayer computeMinMax + rescaling methods, and use of rescaleToZeroToOneRange by default.

examples/osgvolume/osgvolume.cpp

@@ -2215,7 +2215,6 @@ int main( int argc, char **argv )
                 }
                 break;
             }
-                break;
         };
 
     }

include/osgVolume/Layer

@@ -124,6 +124,18 @@ class OSGVOLUME_EXPORT ImageLayer : public Layer
         /** Return const image associated with layer. */
         virtual const osg::Image* getImage() const { return _image.get(); }
                 
+        /** Compute the min and max pixel colors.*/
+        bool computeMinMax(osg::Vec4& min, osg::Vec4& max);
+                
+        /** Apply color transformation to pixels using c' = offset + c * scale .*/
+        void offsetAndScaleImage(const osg::Vec4& offset, const osg::Vec4& scale);
+        
+        /** Compute the min max range of the image, and then remap this to a 0 to 1 range.*/
+        void rescaleToZeroToOneRange();
+               
+        /** Compute the min color component of the image and then translate and pixels by this offset to make the new min component 0.*/
+        void translateMinToZero();
+
         virtual void dirty();
         virtual void setModifiedCount(unsigned int value);
         virtual unsigned int getModifiedCount() const;

src/osgPlugins/dicom/ReaderWriterDICOM.cpp

@@ -122,7 +122,8 @@ class ReaderWriterDICOM : public osgDB::ReaderWriter
             osg::ref_ptr<osgVolume::VolumeTile> tile = new osgVolume::VolumeTile;
             tile->setVolume(volume.get());
             
-            osg::ref_ptr<osgVolume::Layer> layer= new osgVolume::ImageLayer(result.getImage());
+            osg::ref_ptr<osgVolume::ImageLayer> layer= new osgVolume::ImageLayer(result.getImage());
+            layer->rescaleToZeroToOneRange();
             
             tile->setLayer(layer.get());
 

src/osgPlugins/osgVolume/ImageLayer.cpp

@@ -12,6 +12,8 @@
 #include <osgDB/Input>
 #include <osgDB/Output>
 #include <osgDB/ParameterOutput>
+#include <osgDB/FileNameUtils>
+#include <osgDB/FileUtils>
 
 #include <osgVolume/VolumeTile>
 
@@ -44,10 +46,31 @@ bool ImageLayer_readLocalData(osg::Object& obj, osgDB::Input &fr)
 
             if (!deferExternalLayerLoading)
             {
-                osg::ref_ptr<osg::Image> image = fr.readImage(filename.c_str());
+
+                osgDB::FileType fileType = osgDB::fileType(filename);
+                if (fileType == osgDB::FILE_NOT_FOUND)
+                {
+                    filename = osgDB::findDataFile(filename);
+                    fileType = osgDB::fileType(filename);
+                }
+
+                osg::ref_ptr<osg::Image> image;
+                if (fileType == osgDB::DIRECTORY)
+                {
+                    image = osgDB::readImageFile(filename+".dicom");
+                    
+                }
+                else if (fileType == osgDB::REGULAR_FILE)
+                {
+                    image = osgDB::readImageFile( filename );
+                }
+
+                osg::notify(osg::NOTICE)<<"image "<<filename<<" pixelFormat "<<std::hex<<image->getPixelFormat()<<" textureFormat "<<image->getInternalTextureFormat()<<" dataType "<<image->getDataType()<<std::endl;
+
                 if (image.valid())
                 {                
                     layer.setImage(image.get());
+                    layer.rescaleToZeroToOneRange();
                 }
             }
         }

src/osgVolume/Layer.cpp

@@ -13,13 +13,14 @@
 
 #include <osgVolume/Layer>
 
+#include <osg/ImageUtils>
 #include <osg/Notify>
 #include <osg/io_utils>
 
 using namespace osgVolume;
 
 Layer::Layer():
-    _minFilter(osg::Texture::LINEAR_MIPMAP_LINEAR),
+    _minFilter(osg::Texture::LINEAR),
     _magFilter(osg::Texture::LINEAR)
 {
 }
@@ -110,7 +111,58 @@ unsigned int ImageLayer::getModifiedCount() const
     else return _image->getModifiedCount();
 }
 
+bool ImageLayer::computeMinMax(osg::Vec4& minValue, osg::Vec4& maxValue)
+{
+    if (_image.valid()) return osg::computeMinMax(_image.get(), minValue, maxValue);
+    else return false;
+}
 
+void ImageLayer::offsetAndScaleImage(const osg::Vec4& offset, const osg::Vec4& scale)
+{
+    if (!_image) return;
+    
+    osg::offsetAndScaleImage(_image.get(), offset, scale);
+}
+
+void ImageLayer::rescaleToZeroToOneRange()
+{
+    osg::Vec4 minValue, maxValue;
+    if (computeMinMax(minValue, maxValue))
+    {
+        float minComponent = minValue[0];
+        minComponent = osg::minimum(minComponent,minValue[1]);
+        minComponent = osg::minimum(minComponent,minValue[2]);
+        minComponent = osg::minimum(minComponent,minValue[3]);
+
+        float maxComponent = maxValue[0];
+        maxComponent = osg::maximum(maxComponent,maxValue[1]);
+        maxComponent = osg::maximum(maxComponent,maxValue[2]);
+        maxComponent = osg::maximum(maxComponent,maxValue[3]);
+        
+        float scale = 0.99f/(maxComponent-minComponent);
+        float offset = -minComponent * scale;
+
+        offsetAndScaleImage(osg::Vec4(offset, offset, offset, offset),
+                            osg::Vec4(scale, scale, scale, scale));
+    }
+}
+
+void ImageLayer::translateMinToZero()
+{
+    osg::Vec4 minValue, maxValue;
+    if (computeMinMax(minValue, maxValue))
+    {
+        float minComponent = minValue[0];
+        minComponent = osg::minimum(minComponent,minValue[1]);
+        minComponent = osg::minimum(minComponent,minValue[2]);
+        minComponent = osg::minimum(minComponent,minValue[3]);
+
+        float offset = -minComponent;
+
+        offsetAndScaleImage(osg::Vec4(offset, offset, offset, offset),
+                            osg::Vec4(1.0f, 1.0f, 1.0f, 1.0f));
+    }
+}
 
 /////////////////////////////////////////////////////////////////////////////
 //