Some more offline comments and testing recently have raised a critical issue; the use of Square Pixel Sampling and Non-Square Sample Formats. Before that though, let's talk about validation testing. When we get to this level of detail especially, it is important to validate our processing, tools, and complete process. Correcting Aspect Ratio is certainly no exception. In fact, I think we would all agree that when this level of detail really matters, you must validate. Lots of great resources out there about that topic.

There ARE Non-square samples, and their shape IS NOT dependent on the # of scanning lines. There are also Non-Square picture elements in CCD and CMOS image sensors, but their electrical charge is never converted to digital in an analog CCTV camera.

Back in the day there actually were Non-Square pixel-based displays, but they were only used for special applications and are not found in the wild today.

If you are aware of a standard that defines the shape of 480i (NTSC) or 576i (PAL) non-square samples differently than through the use of the luminance sampling frequencies, please bring that to my attention. Thank you.