A Pixel Is Not A Little Square

(With apologies to Dr. Alvy Ray Smith and his technical memo of the same name.)

Yesterday I posted about some of my early graphics work and included a couple of images illustrating how differently graphics would be drawn with relatively modest improvements of computer display capabilities. I noted that the images displayed weren’t necessarily true representations of how the original looked because of changes in display technology. While that’s true, it’s an incomplete explanation, as not only does the display type affect the appearance of the image, but there’s the issue of aspect ratio of the pixels that make up the image.

Because of how CRT TVs and monitors like them worked, pixels were never truly square. On the Atari 8-bit computers I was first working on each pixel of the display in the mode used (160×192) was roughly 1.8×1, and later on the 16-bit Atari ST (low-resolution 320×200 pixels) each pixel was roughly .9×1 As such, any graphic drawn to look correct on such a display ends up looking slightly distorted on modern system with truly square pixels. To better illustrate what these graphics looked like back in their day I’ve rescaled them to correct for the aspect ratio and blurred them a bit to give a better sense of how they displayed.