We are all familiar with CMYK for print, and RBG for screen. With digital still images you can isolate the channels, and this does have a practical use with high end color correction.
There is an open source piece of software called Processing. This set is channel shifting. This series is randomized – once the image file is written into the code and you click process – something different happens every time.
Much like CMYK where each plate is separated in commercial offset printing (I can’t believe I used to have to approve ‘separations’ – and be able to read density in color) – in RGB, these three channels are ones that are offset to create the overlay effect. One of the other random effects is the co-ordinates – either left to right or top to bottom, much like an old TV needing to be tuned to lock the signal.
So, even though there might not seen to be an immediate practical use, it can become an art generator producing unexpected and hopefully inspiring results. Certainly a good process to know how to use.