I think there is a slight overload of terminology here. The samples in the source image, and the tiny light sources that vary in intensity and are driven by a

I think there is a slight overload of terminology here. The samples in the source image, and the tiny light sources that vary in intensity and are driven by a voltage after the information in the bits in the source image has traveled through the display pipeline are two different things. The author discusses the best way to think about the source image. It will get really awkward if we want to discuss imaging algorithms and have to define "my pixel is a square... if it's a bunch of weird shapes the transform is this... etc." It's easiest from this point of view to think of the source image as a lattice of point samples and figure out what the sampling function (our physical pixels) do to the image after we have figured out the math on the point sample source.