A frame of 1080i video consists of two sequential fields of 1920 horizontal and 1080 vertical pixels.
Most movies come in wide-screen format, however, so you lose some of those 480 vertical pixels to black letterbox bars.
Resolution is given in horizontal by vertical pixels.
The number of vertical pixels is calculated from the horizontal resolution and the selected aspect ratio.
Well, I don't think a movie lover would object to a standard 16:10 screen with some more vertical pixels, actually.
Therefore, the Optacon was designed with 24 vertical pixels instead of 12.
Currently, the chips are able to handle a maximum resolution of 1,024 horizontal by 512 vertical pixels allowing delivery of extremely high resolution still images.
With the pushbroom approach, the focusing slit reduces the image height to the equivalent of one vertical pixel, creating a horizontal line image.
As a result, the vertical pixels are coincident to the spectra produced from the diffraction grating.
Side menus make sense now that most monitors are widescreen, since vertical pixels are much more valuable than horizontal.