Dunk,
I think in the real world we always work with images which have been debayered.
The algorithm used can make a big difference to the outcome.
The bilinear method gives a lower resolution when compared with the more sophisticated VNG (variable number of gradients) model.
Dr. Craig Stark summary:
Thus, your 8 megapixel DSLR
has 8 million pixels, but only 4 million green pixels and only 2 million red and 2 million blue pixels.
This has led to the belief that the resolution of such images is far below that of a monochrome camera and that the quality is necessarily much lower as a result of this Bayer matrix and the debayering process.
While encoding the image into a Bayer matrix and reconstructing it does involve interpolation and can be done in ways that are horribly inaccurate, the loss need not be severe.
Full paper is here:
http://www.stark-labs.com/craig/reso...yering_API.pdf