While rarely mentioned over the decades, vertical filtering, which removes horizontal detail in your image, has been around as long as CRT has and is still used to this day in displays and source scaling. Even with the arrival of DTV in 1998, vertical filtering was commonly used in the video circuits of consumer 1080i HDTV CRT displays. For this article we are looking at vertical or horizontal filtering related to luminance response.

The first step with horizontal and vertical filtering is...

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