User Reference:BCI2000Viewer

BCI2000Viewer displays brain signal data and state variables contained in BCI2000 data files.

Opening Files

To open a data file, drag-and-drop it into the program's main window. Alternatively, double-click a .dat file in Windows Explorer, and choose BCI2000 FileViewer when prompted for an application program to associate with the .dat extension.

Browsing

User interface elements for browsing are located at the top right, within the tool bar.

• |<< and >>| move to beginning/end of file;
• << and >> move forward/backward by entire pages (i.e., the amount of time displayed in the window);
• < and > move forward/backward by sample blocks;
• the position field displays the current position in hh:mm:ss format, followed by the total length of the file. Entering a value in seconds, or in hh:mm:ss format, will move the center of the display to the specified position.

Tool Bar

The tool bar contains icons for horizontal and vertical zoom, reducing or enlarging the number of channels displayed on a vertical display page. Also, the tool bar allows to enable and disable the display grid, open and close the channel color selector, and switch between light and dark display mode. Further, there are menus for High Pass, Low Pass, and Notch filter options in the tool bar.

For all tool bar options, there are corresponding menu items in the "View" and the context menu (right-click on the display).

Selecting States and Channels for Display

Once a file is opened in BCI2000 Viewer, the area to the right displays a list of state variables and brain signal channels contained in the data file. By default, all channels are selected for display, and none of the states are. To display one or more state, mark the respective checkbox.

State names and values are displayed above the signal; whenever a state changes its value, a vertical line indicates the respective point in time, and the state's new value appears at the top end of that line.

Display Properties

Similar to the signal display in the operator module, display properties may be changed from the View menu (which is reduplicated as a context menu that appears by right-clicking the signal display).

Also, the following keyboard shortcuts are provided:

up/down	back/forward one channel,
page-up/page-down	back/forward one screenful of channels,
'b'/space	same as page-up/page-down ('less'-like shortcuts),
-/+	reduce/enlarge the signal,
,/.	fewer/more channels,
left/right	slow down/speed up the time sweep,
home/end	jump to the first/last screenful of channels,
typing a number and pressing return (or 'g')	jump to the specified channel number.

Unit Display

When the signal's physical unit is displayed, it is represented as a white bar if the dark theme is selected, and as a black bar if the bright theme is selected.

In the example, there are white markers above and below the bar, indicating the range corresponding to the value written in the bar. These markers may be missing; then the range corresponds to the height of the bar itself.

Finally, the physical unit may be displayed with a marker attached to the bar:

This display is used for nonnegative signals. Here, the physical unit corresponds to the distance of the marker to the signal's baseline.

Choosing Signal Colors

Clicking the color wheel in the toolbar, or the Choose Signal Colors... entry from the context menu, will open up a color chooser dialog.

The Channel Color Selector

This dialog contains the elements of a standard color chooser dialog at the top, followed with two preview fields which display the user's color choice in both the dark and light color context which is available as a choice in the user interface.

Further below, there are three buttons that provide the main functionality of the color selector dialog:

• an "Apply to selected channels" button that applies the current color selection to all selected channels,
• an "Apply pattern" button that applies the pattern in the first N channels to all further channels,
• an "Undo all changes" button that allows the user to go back the colors that were in use when the dialog was first opened.

See also

User Reference:BCI2000FileInfo