Masking
Masks tell the software which pixels to process.
Create a binary mask
From the image menu, select 'Add mask'.
Pixels can be added/removed using the brush/eraser tool. Colored areas are valid pixels.
Use the threshold slider to generate a mask based on the brightness of the background image.
Use the auto-mask feature
From the image menu, select 'Auto-mask'.
The mask is generated by specifying a valid range of values for frequency and an action potential duration (APD50).
Draw a rectangle
From the ROI toolbar, select 'rectangle'.
Click on the image to specify the top left corner, then the bottom right corner.
Draw a polygon
From the ROI toolbar, select 'polygon'.
Click on the image to add points. To close the polygon, click on the first point or select "end" from the right-click menu.
Draw a circle
From the ROI toolbar, select 'circle'.
Click on the image to specify the center location, then set the radius.