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Has author actually seen a CRT TV image in real life? Because it didn't look like that, you didn't have those clear distinct lines. Color CRT displaying a gam

by 323 4y ago

Has author actually seen a CRT TV image in real life? Because it didn't look like that, you didn't have those clear distinct lines. Color CRT displaying a game, no lines: https://i.imgur.com/eI2yb7Y.jpeg https://i.imgur.com/eI2yb7Y.jpeg Black & white CRT, you can barely make out the lines: https://d23gn3985hkc32.cloudfront.net/wp-content/uploads/2020/12/464876-h1.jpg https://d23gn3985hkc32.cloudfront.net/wp-content/uploads/202...

bjt2n3904 4y ago
Yeah -- it seems that so many of the CRT simulations way overemphasize the scan lines. I think if they added a bit of "bloom" to each pixel, it would make them less obvious?
- jeffbee 4y ago
  They over-emphasize the negative space between the scan lines without getting the details of the raster scan correct. The forward scan lines are not horizontal, they are slightly tilted, because the vertical sweep is continuous. The retrace is also slightly slanted, but less because the retrace is faster. So in the diagram on this site the solid lines should be the ones that slope, and the dashed retrace lines should be the ones that are nearly horizontal.
  - toast0 4y ago
    > The forward scan lines are not horizontal, they are slightly tilted, because the vertical sweep is continuous You can slightly tilt the yoke to make the horizontal lines more horizontal (although then vertical lines will be less vertical, tradeoffs everywhere)
Asooka 4y ago
Some CRTs do have visible scanlines, some do not. Check out this thread https://shmups.system11.org/viewtopic.php?f=6&t=63197 https://shmups.system11.org/viewtopic.php?f=6&t=63197 . Personally I'd like the simulated CRT to have no scanlines, rather what I want is temporal ghosting (previous frame blending in the next one, used for transparency effects in games by blinking two images rapidly); and a filter to make pixels less blocky and implement colour bleed. Given the great number of CRTs out there you probably can't have a single one be the best ever, but perhaps emulating several known ones by twiddling the parameters of the shader and letting people pick would be the best.
- jeroenhd 4y ago
  When I look at CRT emulation, I always feel like I'm going crazy. It's been years since I last saw a CRT image but I don't remember visible scanlines at all. I know the retro space is often specifically emulating old hardware, was thing a thing in the 80s, perhaps? Or were visible scanlines more common in America than in Europe? I know the weird colours and lowered resolution of some (emulated) games are an artifact of differences in NTSC/PAL/etc., could that explain the difference?
  - jerf 4y ago
    They seem obsessed with simulated really bad CRTs. I think you could see such scanlines if you were hooking up your Atari 2600 to a TV that was already a decade old, then sat right on top of it instead of across the living room because the cords were short and you wanted to see your games. I've seen it on some arcade games, for similar reasons. But in general, CRTs didn't have those plainly obvious lines, no, because... the engineers would have engineered them out! And did. They're plainly unsightly and it isn't that hard to remove them, after all. I imagine part of it is the need to have visible differences strongly emphasized so it looks like the filters are doing something. A true CRT filter would be much more subtle and people might not thing anything has happened when you turn it on.
    - orbital-decay 4y ago
      >They seem obsessed with simulated really bad CRTs. ... I imagine part of it is the need to have visible differences strongly emphasized so it looks like the filters are doing something. The main reason for that is that games of the era were targeted at the most common hardware, using very cheap composite circuits and CRTs as medium for artistic expression. In many games, you could easily miss gradients, rainbow effects, transparency, or something else with a high-end CRT.
      - Asooka 4y ago
        That seems pretty far-fetched. Do you have examples of such effects being shown wrong on CRTs without scanlines?
an1sotropy 4y ago
Another way to think about the horizontal scanlines is that within the lines, there is really a continuous analog signal, undergoing various (analog) filters along the way from initial detection up through final display, but between scanlines there is discrete sampling. This can be emulated by digital filters, but even if the final display doesn't show the scanlines, there should be a different point-spread-function in the horizontal versus the vertical direction. There's also the possibility of emulating how the time resolution could be less than the refresh rate (sometimes sluggish phosphors create a kind of motion blur). Really old tv transmissions also had an effects like a high-pass filtering (I think to show better detail within limited dynamic range)[1], and how really bright spots would be surrounded by dark halos [2]. The distinctive "look" of old TV has a lot to do not just with the CRT display, but the characteristics of the analog method of video signal generation, in a video camera tube [3] that had its own cathode raw sweeping across the source image. [1] look at the edges of the desk at around 0:36 in https://www.newsweek.com/wmttv-black-white-color-first-time-tv-news-1695871 https://www.newsweek.com/wmttv-black-white-color-first-time-... [2] https://movies.stackexchange.com/questions/113358/whats-with-dark-shining-in-old-black-and-white-tv https://movies.stackexchange.com/questions/113358/whats-with... [3] https://en.wikipedia.org/wiki/Video_camera_tube https://en.wikipedia.org/wiki/Video_camera_tube
werdnapk 4y ago
I recall as a kid, getting right up close to the screen and looking at the picture on the TV and noticing the lines. Further away from the TV, then yes, the lines were not visible.
mras0 4y ago
Guess it depends. I haven't had a CRT TV for many years, but I have an old multisync CRT monitor and I can clearly see the individual raster lines (close up of 320x200 progressive scan: https://i.imgur.com/Osc4ZMm.jpeg https://i.imgur.com/Osc4ZMm.jpeg). At normal viewing distances it's not noticeable though.
- dm319 4y ago
  Deluxe Paint, ah! fond memories!
- smusamashah 4y ago
  > At normal viewing distances Yes thats what it was all about. The pixelated game graphics were made with that and other CRT properties in mind.
  - mras0 4y ago
    Yeah, and I seem to recall reading an article about some of the good old tricks (think it was about the Aladdin game?), but unfortunately I can't seem to find it now. Doing the dithering (by hand) just right would give a good effect in practice. Things made for real higher resolution monitors looked bad on lowres CRTs though (with very distinct scanline effects) as I recall like the menubar in my screen cap, even at a distance.
- hulitu 4y ago
  > multisync CRT monitor > 320x200 21" by chance ? Why would someone use 320x200 on a monitor when only the very old DOS games need such a mode ?
  - mras0 4y ago
    14" 1994 vintage Microvitec. Very popular monitor for Amiga systems because it supports 15KHz horizontal refresh rate modes (PAL/NTSC TV standard - for games/demos) up to 31KHz+ (VGA) for nice flicker free 640x480 60Hz display ("productivity") modes for serious stuff.
- 4y ago
naikrovek 4y ago
I had a consumer CRT as a child (the family TV in the living room) whose scanlines were apparent even at 6ft away, and it was only a 19" screen. maybe my eyes were better than most, I don't know, but I distinctly remember trying to adjust the settings so the lines would go away, thus reducing the annoyance of my "all I can see is colored lines" brother.
hulitu 4y ago
It seems that he didn't. And he also does not understand how a cathodic tube works (i.e. persistence).
SyneRyder 4y ago
> Color CRT displaying a game, no lines: https://i.imgur.com/eI2yb7Y.jpeg https://i.imgur.com/eI2yb7Y.jpeg Try loading the 4000x3000 version of that image you linked and zooming to full size. Especially on the green character's outfit, you can see the scanlines on that color CRT display.
- 323 4y ago
  If you put your eyeball to the screen, sure, just like you can see the pixels of an LCD screen. But it's not how you're supposed to look at it.
ogurechny 4y ago
Along with different properties of the beam other comments mention, there was also a question of dot pitch, i. e. properties of the phosphor grid. Also, the circuits generating the signals in consumer hardware often did not have that much of the full bandwidth, or the most correct wave forms.
kevin_thibedeau 4y ago
That is a late 90s television with a small tube. You can most definitely see the scanlines on old arcade CRTs. The shadowmask on a color CRT enhances the lines so comparison to B&W isn't meaningful.
wormik 4y ago
Imho electron gun alignment topic - see https://www.javatpoint.com/computer-graphics-color-crt-monitors https://www.javatpoint.com/computer-graphics-color-crt-monit...

by 323 4y ago

bjt2n3904 4y ago

Yeah -- it seems that so many of the CRT simulations way overemphasize the scan lines. I think if they added a bit of "bloom" to each pixel, it would make them less obvious?

jeffbee 4y ago
They over-emphasize the negative space between the scan lines without getting the details of the raster scan correct. The forward scan lines are not horizontal, they are slightly tilted, because the vertical sweep is continuous. The retrace is also slightly slanted, but less because the retrace is faster. So in the diagram on this site the solid lines should be the ones that slope, and the dashed retrace lines should be the ones that are nearly horizontal.
- toast0 4y ago
  > The forward scan lines are not horizontal, they are slightly tilted, because the vertical sweep is continuous You can slightly tilt the yoke to make the horizontal lines more horizontal (although then vertical lines will be less vertical, tradeoffs everywhere)

Asooka 4y ago

Some CRTs do have visible scanlines, some do not. Check out this thread https://shmups.system11.org/viewtopic.php?f=6&t=63197 https://shmups.system11.org/viewtopic.php?f=6&t=63197 . Personally I'd like the simulated CRT to have no scanlines, rather what I want is temporal ghosting (previous frame blending in the next one, used for transparency effects in games by blinking two images rapidly); and a filter to make pixels less blocky and implement colour bleed. Given the great number of CRTs out there you probably can't have a single one be the best ever, but perhaps emulating several known ones by twiddling the parameters of the shader and letting people pick would be the best.

jeroenhd 4y ago
When I look at CRT emulation, I always feel like I'm going crazy. It's been years since I last saw a CRT image but I don't remember visible scanlines at all. I know the retro space is often specifically emulating old hardware, was thing a thing in the 80s, perhaps? Or were visible scanlines more common in America than in Europe? I know the weird colours and lowered resolution of some (emulated) games are an artifact of differences in NTSC/PAL/etc., could that explain the difference?
- jerf 4y ago
  They seem obsessed with simulated really bad CRTs. I think you could see such scanlines if you were hooking up your Atari 2600 to a TV that was already a decade old, then sat right on top of it instead of across the living room because the cords were short and you wanted to see your games. I've seen it on some arcade games, for similar reasons. But in general, CRTs didn't have those plainly obvious lines, no, because... the engineers would have engineered them out! And did. They're plainly unsightly and it isn't that hard to remove them, after all. I imagine part of it is the need to have visible differences strongly emphasized so it looks like the filters are doing something. A true CRT filter would be much more subtle and people might not thing anything has happened when you turn it on.
  - orbital-decay 4y ago
    >They seem obsessed with simulated really bad CRTs. ... I imagine part of it is the need to have visible differences strongly emphasized so it looks like the filters are doing something. The main reason for that is that games of the era were targeted at the most common hardware, using very cheap composite circuits and CRTs as medium for artistic expression. In many games, you could easily miss gradients, rainbow effects, transparency, or something else with a high-end CRT.
    - Asooka 4y ago
      That seems pretty far-fetched. Do you have examples of such effects being shown wrong on CRTs without scanlines?

an1sotropy 4y ago

Another way to think about the horizontal scanlines is that within the lines, there is really a continuous analog signal, undergoing various (analog) filters along the way from initial detection up through final display, but between scanlines there is discrete sampling. This can be emulated by digital filters, but even if the final display doesn't show the scanlines, there should be a different point-spread-function in the horizontal versus the vertical direction. There's also the possibility of emulating how the time resolution could be less than the refresh rate (sometimes sluggish phosphors create a kind of motion blur). Really old tv transmissions also had an effects like a high-pass filtering (I think to show better detail within limited dynamic range)[1], and how really bright spots would be surrounded by dark halos [2]. The distinctive "look" of old TV has a lot to do not just with the CRT display, but the characteristics of the analog method of video signal generation, in a video camera tube [3] that had its own cathode raw sweeping across the source image. [1] look at the edges of the desk at around 0:36 in https://www.newsweek.com/wmttv-black-white-color-first-time-tv-news-1695871 https://www.newsweek.com/wmttv-black-white-color-first-time-... [2] https://movies.stackexchange.com/questions/113358/whats-with-dark-shining-in-old-black-and-white-tv https://movies.stackexchange.com/questions/113358/whats-with... [3] https://en.wikipedia.org/wiki/Video_camera_tube https://en.wikipedia.org/wiki/Video_camera_tube

werdnapk 4y ago

I recall as a kid, getting right up close to the screen and looking at the picture on the TV and noticing the lines. Further away from the TV, then yes, the lines were not visible.

mras0 4y ago

Guess it depends. I haven't had a CRT TV for many years, but I have an old multisync CRT monitor and I can clearly see the individual raster lines (close up of 320x200 progressive scan: https://i.imgur.com/Osc4ZMm.jpeg https://i.imgur.com/Osc4ZMm.jpeg). At normal viewing distances it's not noticeable though.

dm319 4y ago
Deluxe Paint, ah! fond memories!
smusamashah 4y ago
> At normal viewing distances Yes thats what it was all about. The pixelated game graphics were made with that and other CRT properties in mind.
- mras0 4y ago
  Yeah, and I seem to recall reading an article about some of the good old tricks (think it was about the Aladdin game?), but unfortunately I can't seem to find it now. Doing the dithering (by hand) just right would give a good effect in practice. Things made for real higher resolution monitors looked bad on lowres CRTs though (with very distinct scanline effects) as I recall like the menubar in my screen cap, even at a distance.
hulitu 4y ago
> multisync CRT monitor > 320x200 21" by chance ? Why would someone use 320x200 on a monitor when only the very old DOS games need such a mode ?
- mras0 4y ago
  14" 1994 vintage Microvitec. Very popular monitor for Amiga systems because it supports 15KHz horizontal refresh rate modes (PAL/NTSC TV standard - for games/demos) up to 31KHz+ (VGA) for nice flicker free 640x480 60Hz display ("productivity") modes for serious stuff.
4y ago

naikrovek 4y ago

I had a consumer CRT as a child (the family TV in the living room) whose scanlines were apparent even at 6ft away, and it was only a 19" screen. maybe my eyes were better than most, I don't know, but I distinctly remember trying to adjust the settings so the lines would go away, thus reducing the annoyance of my "all I can see is colored lines" brother.

hulitu 4y ago

It seems that he didn't. And he also does not understand how a cathodic tube works (i.e. persistence).

SyneRyder 4y ago

> Color CRT displaying a game, no lines: https://i.imgur.com/eI2yb7Y.jpeg https://i.imgur.com/eI2yb7Y.jpeg Try loading the 4000x3000 version of that image you linked and zooming to full size. Especially on the green character's outfit, you can see the scanlines on that color CRT display.

323 4y ago
If you put your eyeball to the screen, sure, just like you can see the pixels of an LCD screen. But it's not how you're supposed to look at it.

ogurechny 4y ago

Along with different properties of the beam other comments mention, there was also a question of dot pitch, i. e. properties of the phosphor grid. Also, the circuits generating the signals in consumer hardware often did not have that much of the full bandwidth, or the most correct wave forms.

kevin_thibedeau 4y ago

That is a late 90s television with a small tube. You can most definitely see the scanlines on old arcade CRTs. The shadowmask on a color CRT enhances the lines so comparison to B&W isn't meaningful.

wormik 4y ago

Imho electron gun alignment topic - see https://www.javatpoint.com/computer-graphics-color-crt-monitors https://www.javatpoint.com/computer-graphics-color-crt-monit...