Comment by creeble

The 'point' of Alvy's article is that pixels should be treated as point sources when manipulating them, not when displaying them.

Obviously, when a pile of pixels is shown on a screen (or for that matter, collected from a camera's CCD, or blobbed by ink on a piece of paper), it will have some shape: The shape of the LCD matrix, the shape of the physical sensor, the shape of the ink blot. But those aren't pixels, they're the physical shapes of the pixels expressed on some physical medium.

If you're going to manipulate pixels in a computer's memory (like by creating more of them, or fewer), then you'd do best by treating the pixels as sampling points - at this point, the operation is 100% sampling theory, not geometry.

When you're done, and have an XY matrix of pixels again, you'll no doubt have done it so that you can give those pixels _shape_ by displaying them on a screen or sheet of paper or some other medium.