Fig 1 illustrates the EPViz graphical user interface. The “Select File” button allows the user to load an EDF file containing multi-channel EEG data. The popup window asks the user to select which channels to plot. We have included the standard 10-10, 10-20 and bipolar 10-20 montages as preset selections. The user also has the option to load a custom EEG montage via a separate text file.
The EEG signals appear in the main display pane. Signals from the default montages are color-coded according to hemisphere (red for left, blue for right, and green for the midline). This is in contrast to EDFBrowser, which defaults to plotting all signals in black. Users can change the ordering and number of plotted signals using the “Change Signals” button. Annotations in the EDF files are plotted as “Notes” at the bottom of the display pane. These are particularly relevant for clinical EEG data. Users can vary the time scale of the plot (1, 5, 10, 20, 25, 30, or 45 seconds) using the “Change Window Size” button. Likewise, they can change the intensity scale via the “Change Amplitude” button. Finally, the “Open Zoom” button allows the user to zoom in on a selected region of the plotting window.
EPViz includes basic filtering operations. The high- and low-pass parameters, implemented using the SciPy library, can be set in the “Change Filter” pop-up. To allow for real-time updating, only the region shown on the screen is filtered. These filtering operations mimic those used in epilepsy and BCI applications. More complex preprocessing, such as ICA, should be done offline prior to loading the file into EPViz.
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