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Another question about color computers in the days of CRT televisions!

There is a consensus that pixels should be square, and so they typically are on purpose-designed monitors. However, looking at a close-up of pixels from a CRT TV:

enter image description here

... they definitely do not look square; they look to me about as rectangular as the screen itself, maybe 4:3, which suggests horizontal resolution should be about the same as vertical resolution?

The other thing that jumps out at me is that the columns of pixels are offset half a pixel height, which is the last thing I was expecting on a system that scans by horizontal lines. What's going on with that? Does the electron beam half-light two pixels every other pixel? Does it have anything to do with interlacing?

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That's just one of many phosphor patterns used by electron-beam televisions. – Mark 12 hours ago
up vote 10 down vote accepted

CRT TVs are analog devices, there is no "pixel", but the size of the spot limits the resolution of the image, as the size of silver nitrate crystals limits the resolution of photo films.

Several arrangements of the colour stripes on the CRT tubes have been designed, they are a compromise between resolution, luminosity and the precise alignment of the electron cannons and shadow mask.

Trinitron CRTs, with vertical stripes, made very good computer monitors. For interlaced analog TV signals, the pattern above with staggered pixels is probably better and more mechanically stable than a rectangular array.

At the age of CRT displays, there was no exact alignment of pixels to the phosphors patterns, like it is common nowadays with LCD screens. The analog bandwidth and dispersion of electrons made every pixel a gaussian circle. The coloured mask is overlaid over this circle, phosphors are unevenly lit.

(Of course, you can ask Wikipedia about "Aperture Grille" vs. "Shadow Mask")

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1  
Relevant: A Pixel is Not A Little Square (PDF). – FighterJet 13 hours ago
    
Indeed, the shape of the electron gun's beam is a Gaussian distribution – Nayuki 10 hours ago

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