How a TV Works in Slow Motion - The Slow Mo Guys

That's not quite true. Only one pixel is being activated at a time but the phosphors continue to emit light for many pixels. In practice you get a handful of lines lit to varying degrees at at time. Maybe 1-2 lines quite brightly lit and then a trail of lines that are fading pretty significantly (but still emitting light). They yes, our persistence of vision fills in the rest to provide the appearance of a fully lit screen. This video has some great slow-mo of CRTs ▶ this video

in “JPEG Compression” · View on HN

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: ▶ this video

in “How does a screen work?” · View on HN

They frequently flicker or are only showing part of an image in video footage or photos, for exactly this reason. They're a right headache to film clearly. (see this youtube video showing one in slow-motion to get an idea: ▶ this video )

in “Blur Busters Open Source Display Initiative – Refresh Cycle Shaders” · View on HN

That's an oversimplification of the physics. CRT televisions have very low persistence phosphors. If you look at high-speed video of a CRT during a raster scan, the line is visible for far less time than the entire frame [1]. This technique relies on persistence of vision [2] to create the illusion of a complete frame. If you want to calculate the response time of a single dot on the phosphor, it is way down into the microseconds. I don't know enough about OLED displays to comment. I do know that LCDs don't even come close to the speed of CRTs at transitioning through high contrast images, the key to producing fast and responsive motion of sprites (which are high contrast against the background by design in most retro games). [1] ▶ this video [2] [link]

in “Checkmate 19" IPS Retro Monitor” · View on HN

If you look at high speed footage of a CRT monitor, you'll see that only a few scan lines are lit at a time. ▶ this video

in “Simple streetlight hack could protect astronomy from urban light pollution” · View on HN

"The video makes it seems that there's no temporal bleeding on CRTs. This sounds unlikely to me..." There is, but I don't remember it being noticeable even on cheap TVs. I still miss the lack of motion blur that CRTs gave by default. I found a forum post where someone lists these values: "Phosphors in current use for CRT-applications: Red: phosphor = Y2O2S:Eu3+. Lifetime (1/e time) = 150 us, single exponential. Green: phosphor = Zn2SiO4:Mn2+. Lifetime (1/e time) = 10-15 ms. Clearly, this is quite long and is the limiting factor in increasing frame-frequency. Note: the emission decay has a highly non-single-exponential decay --> at long times (~1 s) still some emission can be observed by the eye. This can be seen clearly by looking into the green CRT directly after the image was switched off. However, the intensity is too low to cause problems in an active image when the image-frequency is below ~100 Hz. Blue: phosphor = ZnS:Ag,Cl. Lifetime (1/e time) = ~100-200 us. Note: not single-exponential decay, but no emission at long times. (Source: Shionoya & Yen, "Phosphor Handbook", 1998.)" [link] And in this high framerate video of a CRT you can see the different colors decay at different rates. Here the blue seems to decay the fastest. But they're all imperceptibly dark by the time the scan line comes around again. I have no idea if there's any cumulative effect that's perceptible. ▶ this video [link]

in “How Games Used to Look: Why Retro Gaming on a CRT Looks Different [video]” · View on HN