If you only wish to display a filtered camera image, you can extend the WPICameraExtension SmartDashboard widget and override the processImage() method to apply some filters to the raw image*; you will need to install the
SmartDashboard with Vision extensions.
If you wish to display the filtered camera image side-by-side with the original image, it's a bit more difficult; you'll probably need to copy the WPICameraExtension sources into a new class and modify the paintComponent() method to draw both images to the screen (using "ghetto" Java graphics).
* To be clear--you will need to apply these filters using an image processing library such as JavaCV (WPIJavaCV provides some nice bindings for this). I don't think there's an easy way to access the NIVision libraries in a desktop environment.