Loading the First Image Volume

The first image volume has the following special properties:

• No other images can be displayed until the first image volume has been loaded
• All subsequent image volumes must have the same dimensions as the first image volume and will be discarded if they do not
• Loading a new first image volume will cause any other images to be discarded if they do not match the dimensions of the newly loaded first image volume
• Only the first image volume can be edited or saved

Images must be in Analyze or NIfTI format. MultiTracer is able to automatically detect when the image headers and images need to be byteswapped, so images from different platforms should automatically display correctly.

To load the first volume image:

• From the main MultiTracer window "File" menu, choose "Open First Volume ..."
• In the "Open" dialog box, choose either the 'Analyze File Filter' or the 'NIfTI File Filter' depending on which type of file you want to open (Selecting the NIfTI file filter will also display Analyze format files since the .hdr suffix is allowed for NIfTI files).
• Select the .hdr file or .nii file that you want to open from the "Open" dialog box. If the file is not in the current directory, the popup menu in the upper left of the dialogue box will let you move up the directory tree, or you can double click on a subdirectory icon to move down the directory tree.
• If the file that you have selected is a supported data type, the x-dim, y-dim, z-dim, t-dim x-size, y-size, z-size, bits/pixel and data type fields in the Open dialog will populate with values from the header. If these fields remain blank, the file is not a supported data type and any attempt to load the file will fail.
• If the t-dim of the file is greater than one, the "Load volumes" fields in the Open dialog will be editable, allowing you to specify the range of volumes that you want to load (the default is to load all volumes). Acceptable values for these fields range from one to t-dim, and the value in the first field must be less than or equal to the value in the second field. Editing is not supported when multiple volumes from a single file are loaded into the same slot, so if you want to be able to edit, both fields should specify the same volume number.
• Once the file is selected, click the "Open" button in the dialogue box to load the file.
• Large files may take several seconds to load; a status bar may appear to show your progress.
• Once the file is loaded, the image should appear in the display region. If no prior image has been loaded, MultiTracer will automatically take you to a plane in the middle of the image and will adjust the intensity of the display to a (usually) reasonable value. If the display appears black, this may reflect a problem with the automatic intensity adjustment, and you may need to set the intensity manually.

If you have already loaded a file and choose to load a new first image volume with different dimensions, any tracings of structures will be discarded (you will be given a opportunity to save them first). Nonetheless, it is always a good idea to save your traces before you load a new image.

If you have previously loaded a file and choose to load a new first image volume with the same dimensions, you will be given the option to discard or to retain any existing traces.

Modified: August 27, 2012