You all know better than me. I added that comment a while ago in response to something, but I don't remember why any more and haven't used that member since.- in DensityHeader there is a confusing comment: ... float Objectpixelsize; //this is the actual pixelsize float Microscope; //Microscope + //! Use this to set the size of the voxel float Pixelsize; //Pixelsize - used for the microscope CCD camera ... the comment should probably apply to Objectpixelsize.