Voxel Intensities

From the user's perspective, each voxel in a NIftI file potentially has two voxel intensities. The first is the raw voxel intensity, which can only take values representable by the underlying file type. For example, unsigned short integers can only represent values from 0 to 65535. The second, optional voxel intensity is a calibrated voxel intensity based on application of a scaling slope and intercept stored in the header. The raw voxel intensity corresponding to the current mouse cursor location is displayed in the lower right hand corner of the main display window. If the cursor is located over a single volume NIfTI file that includes calibration factors, the raw intensity is followed by a colon and then the calibrated voxel intensity, followed by "(cal)". Voxel intensities are not displayed when multiple volumes from a single NIfTI or Analyze file have been loaded into a single MultiTracer display slot. In this case "t_dim>1" will appear in the location where voxel intensities are normally displayed

For Analyze 7.5 files, only the raw voxel intensity is displayed

The raw (uncalibrated) voxel intensity is the value used in the "Unscaled values < __ are black" field of the "Image Intensity" control panel

Modified: August 27, 2012