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How does a screen work?

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572 points chkhd | 1 comments | 13 Jul 25 14:09 UTC | HN request time: 0.209s | source
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retrac ◴[13 Jul 25 16:39 UTC] No.44551618[source]▶
CRTs are still slightly magical to me. The image doesn't really exist. It's an illusion. If your eyes operated at electronic speeds, you would see a single incredibly bright dot-point drawing the raster pattern over and over. This YouTube video by "The Slow Mo Guys" shows this in action: https://youtu.be/3BJU2drrtCM?t=190
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hinterlands ◴[13 Jul 25 16:59 UTC] No.44551773[source]▶
That slo-mo video is somewhat misleading, though. The phosphor glows for a good while, so there is a reasonable chunk of the image that's visible at any given time.

The problem in that video is that the exact location the beam is hitting is momentarily very bright, so they calibrated the exposure to that and everything else looks really dark.

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1. f1shy ◴[13 Jul 25 18:06 UTC] No.44552235[source]▶
And still it was possible as a side attack, with just looking at the reflected brightness of a screen, to get a perfect image back.