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Labels, or ROIs, are collections of vertices that can be treated as a group for various applications. In TkSurfer, you can use labels to get average values for overlays or time courses. You can also export label files for use in other FreeSurfer programs, or export a collection of labels as an annotation.
TkSurfer can have multiple labels, each with a different designation. Labels in TkSurfer can be associated with anatomical areas or just be given a color for display purposes. TkSurfer has drawing and filling tools to assist you in creating new lables based on surface data.
Many operations use labels, such as graphing the average of a label in the Time Course. You must select a label for these operations. The currenlty selected label is drawn with a yellow outline in the Display window, and its name is highlighted in the list of labels in the Labels window. To select a label, click on it in the Display window, or click on its name in the Labels window.
Use File->Label->Load Label... item to load an individual label file. A label file is a list of RAS coordinates and associated vertex indices that make up the label
You can also import an annotation file as a series of labels. An annotation file is a binary file that assigns a label index to each vertex in a surface. When the annotation is imported, a label is created for each unique index, and the vertices with those values are added to that label. This can be done with the File->Label->Import Annotation... command.
Label files can be associated with anatomical labels, analogous to a segementation volume in TkMedit. To do this, TkSurfer must load a lookup table to get its list of structures. Each structure is associated with a number and color. Each label assigned an anatomical structure will be drawn in that color. When an annotation is loaded, it uses the numbers in this table to assign structures to the imported labels. TkSurfer loads surface_labels.txt by default, but you can load a new table with the File->Label->Load Color Table... command.
Use File->Label->Save Selected Label... command to save a new label file in a new location. You can select a label by clicking on it in the Display window or by selecting its name in the Labels Window.
The Labels window, accessible through the View->Windows->Labels command, displays all labels and their properties. On the left side is a list of labels. Click on one to select it. You will the label selected in the Display window if it is visible in the current surface orientation.
When you click on a label, you can edit its properties on the right side of the Labels window. The following properties are available:
Name: Enter a new name in the field and press return to set the label name. This only really has an affect on the display in the label list on the left side of the window.
Visible: Uncheck this to hide the label.
Choose a color: A Label can either be a 'free' label or a 'structure' label. If it is free, you can assign to it any color you'd like with this area. You can also do this with the far right button in the main toolbar.
Or a structure: If a label is a structure label, you assign to it a structure and its color is set from the corresponding color in the look up table.
Set Name: Click this button to set the name of the label to the name of the structure you have selected for this label.