These Are Not Pixels: Revisited
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- เผยแพร่เมื่อ 21 เม.ย. 2018
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When I first made a video on analog color television, the thumbnail I created (and its explanation) caused nearly endless debate. I thought I'd try and clear this up a bit.
Here's the video on how analog television works (you may notice I recycled some footage from it)
• Lines of Light: How An...
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"Theres no regularity in this noise" yt compression: allow me to introduce myself
This needs more up votes
Yeah, I saw the blocks :D :D But imagine seeing this in person. There's no compression in your eye, right? Well, apart from the persistence of vision. Would you see these blocks created by the compression algorithm? Think about that way. There's no vertical separation of the lines. Those blocks you see in this video are result of the post-processing that compresses this video. TH-cam doesn't deal very nicely with snow, confetti or any other noise patterns. Because of the unpredictable pattern, the coder doesn't know how to encode it seamlessly without any noticeable lose of details (that's why it's called lossy compression - it loses details in order to save up some space). TH-cam uses ever so standard H.264 compression scheme (which is mostly used by your digital TV broadcast - the newest upgrade is of course H.265 or HEVC, which is slowly taking over the digital terrestrial broadcast worldwide). Those blocks you see are mere result of the algorithm trying to figure out how to draw the picture with less details without it being noticed. And it fails, so what it does is it just quantizes the image and doesn't care about the visibility of artifacts.
TL;DR: I know this is a joke, but I really had to write a sum up :)
@@CZghost Thats a good explanation of whats happening here, but
Actually our brain does compress (and structurise) what eyes see, because most of what eyes see is useless. Brain cuts out stuff that you're not focused on, seeks for regions of similiar colors, to put it as one big color blob instead of thousands of "pixels" that retina consists of. And, in this noise, as in any random noise, will be regions that darker or brighter, or mostly grey actually, what our brain will compress to: horisontal straight lines, mostly grey, changing fast. And some of the more persistent darker spots, of course.
What do you think?
How do you mean? Is "youtube compression" different than normal mpeg-compession?
@@henryokeeffe5835 upvotes lmfao
Howdy!
Just to make a clarification, the three electron beams inside the tube are all the same--they are not actually colored, Red, Green, and Blue. It's the phosphors at the front of the tube that glow when they are hit with their corresponding beam--it's not like the picture tube is actually projecting three different colors of light. The principle is the same, though. You just need to substitute light for an electron beam for any sort of practical demonstration to be possible.
Hope that makes sense!
Great video!
So what about something like DLP? Don't those use RGB light wheels to project color?
Actually, DLP would make a great new installment of this series! _because 'color wheels' were a very early process of displaying a color image by CBS_
The array of mirrors define the discrete pixels on a DLP.
@MegaTechpc As Ryan explained, the micromirrors on the DLP chip do define discrete, logical pixels. The main difference is that the respsonse time for DLP technology is _ridiculously_ fast, so the pixels can be dithered hundreds of times per frame, thus they produce an RGB image sequentially like the CBS color wheel system from the 1950's.
"In this video I'd like to revisit a concept from my television series"
Many people can have a television series, but there's only one person who can have a series ON televisions
r/ThatsDeep
Now I get it. I thought he meant he had a series (broadcast) on TV, but he actually meant he had a series on (the topic of) TV.
Gorm13 That's interesting. I interpreted it as "a series about televisions", and, until reading this comment, didn't realize that it could be interpreted differently.
Is your pfp an OC?
@@bensoncheung2801 yes, i drew it
The thing that really brings the distinction home for me is that with the closeup of the slot-mask CRT, you can see clearly that the brightness of the image can vary within a single phosphor dot, in a nontrivial way depending on the shape of the image (rather than the color or brightness data at a single spot). That would not be the case if they were truly pixels.
Of course, the issue gets confused somewhat by the way that systems with LCD screens can do "subpixel rendering" by tweaking the color data in a manner that exploits the spatial arrangement of the red, green and blue elements to provide a bit more spatial resolution. But from the physical LCD's perspective, it's just rendering color data as usual.
This is the same point I came to the comments to make.
On a side note though: subpixel rendering is also a cool topic, and the way a text renderer has to be aware of the font shape and its display pixel layout is kind of awesome.
Haha, and don't get me started on PenTile / RGBW displays!
Was thinking the same thing!
That also means that your image is not as sharp and you lose actual detail - cause while you can, if the monitor would be tuned perfectly, get a bit more detail out of the image, at the same time in normal scenarios you lose fidelity.
I wanted to say the exact same thing. Look at his eyebrows at 6:00. That says it all.
Dude! your production value on this is amazing! that editing on the B&W TV was just 😙👌
Agreed, some of the best 'tech' videos on TH-cam. Take note of the 3 color 'tubes' that were used in the demonstration - brilliant work!
very nice idea to use the flashlights. Only my OCD hit me cause one of the flashlight's exteriors was a tad different
I came here to say the same thing. fantastically high quality editing and post production. The 3 CRTs disconnected on the table, but all lit up really messed with me. Amazing job!
Maico Oh I am so with you on that observation, ahhh!
Yup, well done!
TH-cam compression HATED that snow on the CRT
Lmao
If you're a really old school PC gamer, you might remember that early high resolution color CRT monitors used to have the dot pitch heavily touted as one of their key attributes in advertising. Smaller was always better because it meant more phosphors being lit per sweep and thus a sharper image with more detail in areas of rapidly changing pixel values.
John Michaelson This made me feel older than I am 😅
But correct nonetheless :-)
Nah, we're just seasoned veterans! Seeing that Kingdom Hearts demo reminded me of something that I saw back in 1989 when I bought my first gaming rig. It came with a choice of two 640x480 monitors, one had .39mm dot pitch, the other more expensive had .31mm pitch. The better clarity of the latter was startling comparing them both side by side, so much so that it took me a while to grasp what was really happening on the screens and what dot pitch meant compared to the 640x480 part.
...with .28 dot pitch being probably the most popular dpi among them. I remember seeing .28 dpi on just about any monitor I looked at back in the day, with the better branded monitors having models that had smaller dpis, like .27 or (Gasp!) .25
Yes, those pitches came later with 1024x768 monitors especially. I had a cruddy old 14" 1024x768 monitor with .28 pitch in the early 90's that I never actually used at that resolution because it emitted an annoying very high (almost dog hearing level) pitched tone at that resolution, and my video card barely supported it anyway. 1024x768x16-colors isn't very exciting.
This is still a very relevant value, as these days it has to do with the ratio of the screen's physical size to it's native resolution. You can compare a sharp CRT's dot pitch to an LCD's and figure out if you'll be able to make out pixels from across a room, at a desk, etc.. I always buy screens with at least the dot pitch of a good CRT since my vision's too good for my own good.
"for those of us with normal trichromatic color vision anyways"
Goddammit, I almost wanted to write: "*laughs in colorblind*"
Or that one woman that could laugh in tetrachromatic vision. So far the only person proven to have and fully use four color receptors.
@@patrickmccurry1563 ~10% of all woman have tetrachromatic vision. That meme about differences in color perception between man and woman is no joke.
fritt wastaken Yeah but Tetrachromats don’t actually have more perception of color. Men on the other hand can be color blind
@@jerrell1169 they do have more perception depending on how much their 4th type of cone cells differ from other types. Usually it's not much, but rarely zero
@@patrickmccurry1563 Pretty sure there's more than one person proven to have it. But, yeah, it's pretty rare, and I think near impossible for a male to have it.
12:27 "I mean, you can't really blame it. It only has 5 inches to work with."
That's what I keep saying!
The commenters didn't have as much of a field day with that line as I expected, he must have an audience of above the average IQ of the typical TH-cam watcher...
I have something that has 5 inches too 😂😂😂🤣🤣
Reading these responses made my IQ drop 5 inches.
@@byz88 You guys have IQ?
Damn this bro joined 16 yeara ago and is still active, salute
Wow! Nice practical demonstration of a shadow mask, super simple but it gets the point across really well. I’m impressed.
Yeah, I've done this many times for artistic/photographic reasons, but I never made the connection to CRT TVs. I was impressed that this is how he decided to demonstrate it, because it shows that he has a good understanding of what he's talking about and thinks out of the box. Signs of a very smart person.
I'm super impressed.
I have watched this 3 times and I still don't have a clue
I feel like that's a really at-home science experience to do.
And honestly, just looks kindda fun to try.
"It gets the point across." lol. Oddly appropriate for projecting a point of light through a mask.
I learned about how colour TV works when I was 10 (that was 1975), and was quite obsessed with it for a while. I remember explaining it to other kids in my class at school. This is an absolutely perfect educational essay - thank you! Younger people now won't remember the older tech, but if I had to choose something to go into an archive for future generations to understand how things used to work, I'd choose this video. 10/10.
I think the nail in the coffin would have been you sending a BW Kingdom Hearts image to the small CRT TV, showing the (now visible) numbers and letters. Or even sliding the saturation of the signal from BW to color.
Here's the real nail in that coffin. The NTSC colour standard was finalized in 1953. Russell Kirsch invented the pixel in 1957.
Also keep in mind the electron gun in the back of the tube isn't emitting any color. The color comes from the phosphorus panel just behind the face of the screen that get lit up as it's hit by electrons.
Excellent explanation. I've worked with arcade games for 30 years, and have tried to explain to my 9 year old the difference between analog and digital video signals. I finally had her watch your video series on it , because you are much better at explaining it, now she understands. I know it's just semantics to call it a pixel, but no matter how it looks you can't change the mechanics of how a CRT works. Great videos.
Reggie Benes So awesome that you have a 9yo daughter into this stuff 👌🏻
A CRT is like having a fine paintbrush that you can raise or lower as you drag it along the paper. A raster CRT always draws those pictures in a zig-zag pattern. A color raster CRT is like using a mask that changes the color of your paint. An LCD is like using squares of construction paper.
Maybe that'd work better for 9-year-olds
@@SuperSmashDolls also, CRT phosphors can display multiple colors at ONCE. Not across multiple frames. No, a SINGLE phosphor can display MULTIPLE COLORS.... *PER FRAME* . Digital Pixels CANNOT DO THIS!
Sal Nation Uhh, you're mistaken. Digital pixels do not need to alternate between red, green, and blue each frame, and I'm pretty sure your understanding of how phosphors work is also wrong.
@@salnation189 I don't know where you heard that. but it's completely wrong. You should stop spreading misinformation. What you're saying literally doesn't even make any sense if you stop to think about it for more than a nanosecond.
This is great, for the first time I can understand where the huge difference in CRT quality, especially multi-sync monitors comes from. The higher the feed resolution, the finer the shadow mask needs to be in order to avoid pixels of data effectively being lost because whole pixels worth of data are hitting the shadow mask instead of the phosphors.
One detail which I'm sure you sensibly omitted for time: you *can't* reproduce all visible colors with three primaries. You can only produce those inside the gamut of those primaries (a cube-ish shaped subset of all visible colors.)
Some high-purity colors lie outside the gamut. E.g. high saturation cyan can't be reproduced because the green phosphor stimulates the "red" cones somewhat, producing a less saturated color.
These colors are less common in natural images, so it doesn't matter much.
This is why a lot of modern displays have an oversaturated image; they have higher purity color elements, which increase the coverage of the gamut. The most common color standards are based on older tech, so new displays require color correction, which is usually not present because most people don't care if the color is wrong.
Color management is a *real* can of worms. It's actually quite relevant to my job because we tend to buy things like monitors used, and in the 24" class used wide gamut displays are super common while plain sRGB jobs aren't, plus the latter tend to retain their usefulness in plain office environments like ours a lot longer so aren't sold as much. It wouldn't be half as bad if said wide gamut monitors had some usable sRGB emulation, but they tend to be too old for that. (Right now you can get monitors which are barely even 70% sRGB for the sake of efficiency, or sub-60% in laptops, which is getting a bit silly. On the other end of the spectrum you get some super wide gamut coverage. We'd just need 100% sRGB and not too power-hungry.)
Then there are some more snags like low-frequency PWM for LED backlight that tend to rule out other potential candidates. A lot of people may not notice it, but I wouldn't rule out that they aren't negatively affected regardless, and I do not particularly fancy having people use equipment that wouldn't be up to my own standards.
No doubt, it's a huge PITA. One big problem is that most modern "regular gamut" monitors are quite a lot wider than sRGB. So people prepare images on those displays without color management, and they end up looking understatured when you have a properly color-managed workflow, because sRGB is assumed by default (and there's no other reasonable default to assume.)
And if you have a color-managed workflow, the only way to know what your final images look like for most users is to have a second monitor with an "average" gamut and no color-management, then hope for the best.
Can you talk more about the color correction thing? How would I go about that?
While this is correct in theory, in practice a 32-bit color depth of red, green, and blue pixels actually produce *significantly more* colors than what the human eye or brain can actually tell the difference between, in orders of magnitude more. While some colors may still technically not be able to be reproduced, these colors are virtually indistinguishable, again to the human eye and brain, from other very similar colors that _can_ be reproduced.
Sure while adding more colored pixels, like in the ypbpr or cmyk standards, can technically reproduce a higher color resolution, the apparent color resolution is virtually identical.
A really saturated Cyan for instance seeming more pale on RGB screens is not necessarily the fault of RGB itself but is actually a combination of dozens of other factors of the screen (for instance, one uniform backlight which is extremely common in current LCDs, will make most really saturated colors seem a bit paler by comparison to a screen with per-pixel back lighting, as well as not being able to produce a "true" black).
@@Templarfreak more colors than can be told apart within a certain range, yes, but not all colors that human sight can distinguish.
The shirt fits the subjects
LMAOOO!!!!
This is better than anything I've ever watched on TH-cam.. You sir deserve an Oscar for your channel.
Oscar is for acting. So are saying what he is presenting is wrong.
You mean Emmy, right? This is television.
I’m a computer science student and I never understood how color CRTs with their dot masks worked. Thank you sir! That was a wonderful explanation!
I needed you when I was graduating in Computer Engineering. You are 10 times the majority of professors I had.
This is by far the most clear explanation of how the shadow mask works I've seen. The only thing I think you sort of missed out on explaining is that the beams aren't coloured, it's the phosphor dots, but you corrected that in your own comment already.
He clearly explained that the phosphor was colored. Furthermore, Does he seem like a guy that does not understand how Red, Green and Blue Phosphor is controlled with the Electron beam???
I've been working on a faux-CRT shader for Unity, and this video was extremely informative and helpful in figuring out the properties and mechanisms that give it that distinct look.
How did it go ? :) I am currently prototyping a CRT filter, just fooling around in Rust with the pixels library and drawing pixels in a framebuffer (so not a "shader" per say) And I realized that a full HD monitor is just not enough, I really need a very high DPI (retina) to simulate the analog nature of an electron beam.
I just want to say that you are amazing. I've learned so much from you. There are a lot of "good" TH-cam channels, to be sure, but I'd label only a dozen or so as "great." Your videos are, without any reservations, right at the top of that list. You have a really nice way of presenting and it's clear that you aren't just reciting facts. You clearly have a deep intrinsic familiarity with what you talk about and that makes it so easy to learn from you. It would really be a sad day if you ever stopped making these videos. I sincerely just wanted to say thank you!
You do the best video editing of any nostalgia/tech history/education channel I've seen to date. Well done.
I also enjoy your diction, narrative style, clear speaking, and delivery. You explain things well and it just makes watching your videos very enjoyable.
I think you missed a point to help convey your message...
If you pause at 13:58, you can very clearly see that each phosphor dot is actually displaying information from more than one scanline. Sure, some dots are fully lit equally from top to bottom, but many are not -- the top of the dot might be one scanline, and the bottom another. If you look closely enough, you can even see that there are changes in the intensity horizontally within a single dot. The bottom line is that if you were to try to correlate a phosphor dot to a "picture element" the dots are actually displaying multiple elements of the picture simultaneously, and are thus not a single picture element, or "pixel" as we have come to know them.
Similarly, (and you did sort of cover this) any detail in the image which doesn't fall within the area of the corresponding color of phosphor dot just isn't going to be visible. So, in theory, if you had a high resolution image made up entirely of very thin red vertical stripes on a TV with a particularly low dot pitch, it might be possible that you don't see anything at all if those stripes happen to line up in the shadow area of the screen. Also, if you have an RGB stripe TV (like a Trinitron) and a white edge of the picture happens to start on the blue dot and spill over into the red and green dots to its right, it will still appear as white, even though that edge is split across dot groupings. As mentioned, the TV just doesn't care where those dots actually are or how they are arranged -- it just displays what it can where it can and that's good enough.
Yep, as Matt McIrvin brought up, the issue was that this could be confused with the divisions in the color components of the LCD panel. I actually cut this from the script for this reason, but now I'm beginning to regret doing that.
Technology Connections This dude will never understand even though Matt clearly and precisely explained it in this video.
_"any detail in the image which doesn't fall within the area of the corresponding color of phosphor dot just isn't going to be visible."_ The rest of your comment was fine but this point overstates the case. It would be true if the CRT could make a spot on the screen that only lit up one phosphor dot at a time. But It can't. It can't focus the beam anywhere near that tightly.
The beam does not make a phosphor-dot-sized spot of light! Each beam actually excites the dots of its respective color in many triads* at once; it's just brightest in the center of the group. For some details in the desired picture the center of the group corresponds to the location of a dot of the correct color, for others it doesn't. But a blue detail that's supposed to be where the red dot of a triad actually is will still light up blue in the triads around that red dot, and it will still be brightest at the center of all of those triads, just as if the beam's center fell exactly on a triad's blue dot.
As the beam is swept from side to side, both persistence of vision and persistence of the actual phosphorescence help average and blend it all together ,and we see the detail where it's supposed to be. Just as if there was a dot of the correct color right at the middle of the group. The fact that there isn't one doesn't matter much because the CRT is never illuminating just one phosphor dot at a time anyway.
* groups of three phosphor dots. Yes, I know, they're technically only called triads in a shadow mask CRT. But I don't want to type "group of three phosphor dots" over and over when I can type one six-letter word.
it's a pixmaskel not a pixel.
Its fascinating as presumably when displaying a digital image on a CRT you have a situation where one triad will actually be representing more than one pixel, especially on PC monitors where you could be outputting any number of different resolutions to a screen with the same shadow mask. Thus why there is an optimal resolution, because going any higher you run into a situation where a whole pixel could get obscured by the shadow mask itself, made even worse by the fact that the refresh rate gets lower and lower as you increase the resolution, causing a dimmer image.
I never understood this at the time, but it explains why there was effectively a technology war of different shadow mask designs, trying to minimise how much actual mask there was thus allowing a higher resolution to be displayed.
Fantastic video! While I always knew the technology and method behind CRT displays, this video sums things up in a way that is easily digestible.
This is the coolest channel on TH-cam. I've been binging your videos for a while now and I'm loving every. single. one. Thank you for all the effort you put into your top-notch content. It's highly informative and entertaining!
That was an amazing explaination+demonstration! Also, I think you did an excellent job on clarifying this subject in your trinitron video!
Fantastic video
One thing I might add which can really support what you are saying is:
3 CRT color projectors.
Those are just three monochrome displays with a color filter over each of them and they truly demonstrate how there are no subdivisions of any kind in the horizontal lines to define a pixel.
Absolutely love the explanations in these videos, really really considering supporting on Patreon.
James Siggins me too. He would be my first channel I support.
Every single one of your videos are just consistently awesome and interesting. I don't know how you manage to keep up this level of production value across all of your videos. It's quite an accomplishment. Good work.
The attention to detail in these videos is absolutely staggering. There's no other channel that I know of that is as methodical and thorough as this. It's truly a treat 👌 Thank you 🤝
Dude... That tinfoil flashlight thing was seriously amazing!! You rock. Thanks for producing such great content. Just subbed a month ago but this channel is now in my top 5 favorites.
One of the best channels on YT. Keep up the good work Alec!
You really went at it in this video. Showing the mechanism of how the light passes through the mask really helps explaining how CRT screen works.
Really enjoy the level of detail in these, and the example with the torches was a brilliant visualisation. Thanks :)
This episode had some top level editing and creativity in it... So good.
Quite amazing !!! You’re going to great lengths to explain this very thoroughly and yet in a simple-to-understand way. I wonder how many days you spent putting this video together :-)
As usual an excellent presentation. I did a modification to a production unit where i had to convert the display from an analog display to a digital display. Counting pixels played a big part in this.
Keep up the good work, very informative. Well done.
I think squashing/stretching, skewing and otherwise resizing the image on CRT monitors and TVs is a pretty effective way to demonstrate the point you were making about "resolution". The production quality in this vid is sick btw, nice stuff.
Great description, I particularly found the Kingdom Hearts example to be helpful.
For those interested, Retro Game Mechanics Explained has a recent video going deeper into the timing of horizontal/vertical blanking (specifically on the SNES): th-cam.com/video/Q8ph2OVqZeM/w-d-xo.html
Another excellent video, Alec. Clear, presise and easy to understand....and it's ashame that TV only had 5 inches to work with LMAO
Once again, very informative. Thanks for the info.
Great editing, graphics, and cinematography.
(and actual subtitles, which I noticed a lot of creators skip timing. Kudos)
Great description of how this stuff works, taking something fairly complicated like this and explaining it in a way everyone can understand can be tricky but you nailed it. You just got yourself a new subscriber, time to go binge watch some of of your videos!
This video helps everyone remember and appreciate just how far we've come since the 80s with displays. I remember when Active Matrix was a new thing.
And yet, it's hard to reproduce that magic of the CRT with emulators. But using the composite out on an android box on my plasma tv does seem to get you most of the way.
This explained so many of the little holes in my knowledge of CRTs, thank you!
THANK YOU!!! That thumbnail is what drew me to that video and your channel, but I watched it and didn't feel like I got a good explanation. Until now I never understood what you meant, but now it all makes sense!
So glad I subbed.
FANTASTIC production value and dedication to detail. Bravo
Funny biological trivia about the fact that color can be produced by a pure wavelength or a non-spatially resolved mixture in between.
This rules apply to almost all colors (and happens also irl, not only screens), but there is one color that works slighty different and exist only as a mixture. Can you guess which one?
Magenta is the answer. It activates both blue and red cones, so the midway frequency is...green. Which would make the resulting color white. So to obtain the magenta pattern of stimulation you can only use a mixture of blue and red, but pure magenta doesn't exist. This is why in perception we have a color wheel, but if we decompose white light we have a linear rainbow
That actually brings up something I've heard before; the fact that we can never really see a "pure" green, while we sort of can for red and blue. Both red and blue cones have a range of frequencies where they're the only cone that's activated, but green cones are entirely overlapped by the ranges of either red or blue.
Because of that, I've always wondered what we would "see" if the green cones alone were triggered through some sort of direct stimulation, what we would actually perceive from that. Would it look like some kind of super-green or something?
This is a hard question to answer because it plays on some subtle structure of our eyes and of our brain. First, red and green overlap a lot (with a reason actually), while blue is farther away and only partially overlaps with green. Second, this asymmetry is also reflected in structure, as red and green cones make up most of the central, high resolution part of the eye (the fovea), while blue cones and rods fill most of the periphery. During daylight vision, your brain reconstruct high definition black and white images from mini-snapshots received from the fovea while your eyes dart around to cover most of the visual field in HD (this is why the red and green cones are very close, since they also have to act as a b&w high resolution receiver, and optical aberration would mess up the image if the maximum points were too far spread out). Color information is added later, both from parallel green and red channels from the fovea and peripheral blue information, and your brain just plays "fill in the shape". So actually your green and blue cones are never really active from the same point because they are looking at different parts of the visual field, so the effect of pure activation of green might just be corrected out since your brain is already dealing with wonky color information anyway. Also some weird perceptual stuff might play some weird effect, since color information is transformed from 3 separate R/G/B channel in the photoreceptors to two channels, R-G/B-Y, and those get sent to your cortex. So basically I would go for a "no special effect", but I wouldn't bet on it.
However, if you want to see supercolors you might be in luck. We can abuse that weird two-opposing-couples channel scheme to see them. Search google for hyperbolic colors and stygian colors, and also look at the wikipedia page for impossible colors.
Yes, pure magenta does exist. And magenta isn't the only color that "exists only as a mixture". The same goes for greys and white. I know what you mean, but you should have phrased it more precisely: magenta is the only *hue* that is not spectral, i.e. cannot be evoked by light of a single wavelength. Grey and white are colors, but they aren't hues. And spectral colors are very rare in everyday life anyway, most colors you see will be caused by a "mixture" containing several wavelengths.
People should get the notion out of their heads that color and wavelength are the same. They're not. Wavelength is a physical property of light, but color is a subjective perception. Our visual system isn't a spectrometer, it does care about seeing useful differences in the world around us, it does not care about doing a spectral analysis. Most objects are reflective, i.e. they don't emit light of their own. The specifics of the light they reflect does not only depend on the characteristics of the material, but also the light source (and the medium that the light is travelling through). Our visual system has therefore evolved some tricks to try and do the impossible: remove the influence of the light source. This leads to effects such as the checkershadow illusion persci.mit.edu/gallery/checkershadow and this one: www.labofmisfits.com/illusiondemos/Demo%2012.html - where we perceive the same light as different colors, because context matters.
You also wrote "color information is transformed from 3 separate R/G/B channel in the photoreceptors to two channels, R-G/B-Y" - that's not correct either. You are talking about the opponent process, which transforms the three RGB channels of our photoreceptors (disregarding that they aren't actually RGB) to *three* other channels: the two color difference ones you mentioned, plus a brightness one you didn't mention. We actually do something very similar in both analog and digital image/video processing. Look up YUV and YCbCr.
You're right about whites and greys, but I they are way more known from the classical rotating disc/prism experiments.
On the opponent process I was considering only channels that partecipate in color vision, since I nodded already at the brightness channel beforehand. In general I am not going to be anal about terminology and quirks in the youtube comment section, especially since that comment was already too long by itself. I trust people enough to be able to go on google by themselves later if they want more in depth explanation of the visual system. Kind of like Alec glossed over QAM when explaining color television, the one of us that were interested could go look for it by themselves while keeping the information in the video to the point.
"On the opponent process I was considering only channels that partecipate in color vision" - The "brightness channel" does absolutely participate in color vision. You might be thinking of scotopic vision (low-light vision), produced exclusively by the rod cells, which relay no color information. But in photopic vision (daylight), all three channels of the opponent process are needed for the full color information.
It was most interesting for me to see that within one coloured block of a “not a pixel” on the CRT there was actually more light and dark detail. I remember noticing this as a kid looking at my parent’s TV, the picture was more detailed and moved smoothly behind the coloured dots, they weren’t just getting brighter and darker.
Amazing video! The physical demonstrations you do paired with the metaphors behind it make it impossible _not_ to understand the phenomena you're trying to describe!
Anlaog B&W technology without any microprocessor, software and importantly no software bugs! That was amazing. The color tech was later introduced to back backward compatible with B&W sets, like you said they use the same signal with added chroma signal. Again amazing thinking by our predecessors.
Brilliant edit of transitions.
Probably the best physical demonstration of a colour TV I have ever seen.
How many holes (not pixels) did you make in your mask?
456-468
Thanks for counting.
TheHmm43 *IMPRESSIVE.*
Great explanation, I spent pretty much the entire day reading about these stuff, and this video consolidates everything extremely well. Thank you!
Amazing production quality. Brilliant explanation.
i remember back in the day when crt monitors for pc was a thing, you could change resolution and it would be perfect, but now with lcd only native resolution works since there is a fixed pixel amount.
Unfortunately, 960x540 is not recognised as a standard resolution, so 1080p can truly only render 360p video, but that doesn't exist as a standard display resolution either. Technically, 1080p is bad for scaling pixel perfect images from any other recognised screen resolution, but that's what scaling and filtering is here for.
Integer scaling I'm fine with, but fractional scaling and filtering are garbage and totally throw the image quality and intent out the window.
CRT monitors for the PC *are* a thing!
You could do this just fine if you used a much lower resolution on the PC than the LCD's pixels are. Which is basically why it worked on a CRT, because the CRT's dot pitch was much greater than the PC's resolution.
Well, more properly only integer multiples or factors of the resolution work without loss of fidelity further from that of the resolution itself - just as you'd expect
This video is a work of art! Bravo!
Another hilarious and informative video. I am amazed at the collection of electronic devices you have not only accumulated, but can operate effectively and efficiently to demonstrate your points. Your narrative skills and editing are excellent!
Also; my brother and I found that licking our tv screen made the tri-colored dots more visible (through a lens of saliva). Ahh, childhood.
8:20 WOW!! That's a ton of work you put into this. Thank you!
Needs a demo to compare phosphor size: "let's boot up Kingdom Hearts" (of course)
Hey, you passed 100,000 subscribers! Congrats!
Your channel is one of the very best tech documentary sources. Thanks a lot!
As always you did a fantastic job!, Excellent explanation about how CRT TVs work. Keep up the good work, dude. Greetings from Valencia, Spain.
Amazing shadowmask optics illustration.
This is an extremely well done video.
Wow, amazing video! Thank you for producing high quality content like this.
Awesome editing job! Very pro. and i like the subject of your vids. Very interesting. Thank you!
I am super thankful for whatever circumstances brought you to making videos, bro. Your channel is up there with EEVblog and AvE on my list of favorites. You are awesome.
ok, this is three years late, but if you think AvE hitting shit with hammers and cutting boxes with mini chainsaws is anywhere near the level of quality as we see here...I...just don't know what to say. The only reason AvE got popular was because of his clever use of words. He isn't nearly as smart as people seem to think he is.
Nice use of the _Think As A Brick_ album cover - 'I' got it!
Oh my, that was totally unintentional! I didn't even realize the subtext I was creating there. Now that you've pointed it out, I love it!
You have some serious attention to detail man. Great work, I hope you and this channel goes far.
Thanks. Again. A well done series and I can't wait for each new one
Your CRT series is Fantastic!
Tull! Great video dude.
I saw them live when they introduce Thick as a Brick. They were so tight. They must have practiced 20 hours a day. Always love them dudes.
Excellent and very informative video, i have seen all your television videos and sincerely there were some concepts that i have miss. but now i understand better
Already love this channel, watching through some older content and find an LP copy of Thick As A Brick being used for a demo. Now I love it even more.
You are a creator. Congratulations!
PERFECT VIDEO!!!
Honestly the reason why I love this channel is due to the sheer amount of insanely different manners you come up with just to explain this amazing stuff. Keep it up, I love it!
it is always a pleasure to watch your videos; learning is such a delight !
With all the different sources, setups, examples, and macro shots, these videos must take FOREVER to make!
Great video again :) I would like to ask you to make a video about CRT computer monitors, if you could? I ask this because those are talked about by resolution, such as my old Samsung flat screen 17 inch CRT monitors being 1280x1024 resolution, and John Carmack is seen in a photo with a 1920x1080 monitor back in 1995. It might help folks understand what makes a monitor different from a TV. I have to say, I dig every one of your videos like this, being as I am always curious about how things work in technology both new and old. Just recently turned 35, so I have had a chance to see how quickly technology has advanced through the past 3 decades.
That's a great idea, I'd like to see this too. From what I know, CRT monitors worked on the exact same principle as color TVs, they just included more active electronics to control how many lines the tube should draw, and at which speed.
@Carstuff111 you are thinking of $10K Silicon Graphics/Integraph InterView 28hd96 released in 1997(late afair), Carmack used it while working on Quake 3, so picture is from 1998 not 1995. For contrast in 2001 IBM released $20K 3840×2400 LCD, by 2003 it was $8K.
So, let me blow your mind: Your 17" CRT probably could go higher than it's advertised resolution. PC monitors have circuitry to change the frequency of the flyback based on the incoming sync pulses, and thus a range of horizontal and vertical sync frequencies they could be driven at. This is called "multiscan" and is a unique feature of monitors that was implemented to resolve compatibility issues with different PC video cards and resolutions. But it doesn't actually change what the CRT is doing: just painting lines of light onto a surface.
Note how CRTs don't need upscalers! If you reduced your resolution back down to 640x480, you got the exact same output as you would from an identical "640x480" CRT monitor. LCDs need upscalers in order to produce a native image because they *do* have a fixed resolution, because they do have pixels.
@Super Smash Dolls if it could it would be with huge distortions, even highend models like Carmacks 28hd96 werent stellar at the upper side of specs, moire and wonky geometry due to analog channel not keeping up etc.
My Samsung monitors would go a bit higher than 1280x1024, which was their native resolution, however the refresh was painfully slow at native resolution or higher because they could only manage 60Hz or less at that point, which flickered and gave me a headache. I ran them instead at 1024x768 resolution and 85Hz refresh. I was willing to take a hit on over all pixel count in games at the time because I preferred the higher buttery smooth frame rates and no screen flicker. It was a beautiful thing to play a game with 200+FPS with everything cranked and have absolutely no texture tearing like I see on a modern screen anytime the FPS is higher than the refresh rate of the screen.
Bernard Grob's Basic Television and Video was one of my original readings. His first edition was done just as the NTSC was deciding on which color system to implement in TV. I studied Grob's books religiously. I recommend his fifth edition. This is a great video. Great research and well presented. I will say that during my years as an instructor I gave presentations to many technicians all over the U.S. Technicians that had actually studied electronics and the finer details of television and how they worked. They were in the minority. So anyone giving you grief about your presentations may fall into that group and you are doing a fine job teaching. I fully enjoyed the walks down memory lane.
This is the most thorough but also easiest to understand piece of media I've ever seen explain this; thanks to you this concept makes a lot more sense to me now!
That was an unexpected Jethro Tull shout-out.
I now feel the urge to do videos about ... whatever, just for unexpected Jethro Tull shout-outs. Because this is what the world is in bad need for.
"Thick as a Brick" is an awesome album.
was looking for this comment!
Great video! Extremely informative and interesting since I’m fascinated with the technology of CRT’s
This is a fantastic video - one of those explanations where everything just clicks. I was confused about this when I watched the original video but I understand it completely now!
I´am electronic engineer and I love your channel is so great with a good speeches so clear and fluid information, I love it
JETHRO TULL! awesome content!
Thick as a brick!
Great video! Thanks for all the hard work.
Your example with the home-made mask was very useful.
And your explanation of colour resolution on CRTs was interesting.
Well, strictly speaking, the "pixels" on LCD screen aren't pixels either.
The term Pixel existed long before we had LCD screens, and was already in use when computers were hooked up to CRTs. Pixels is a term that comes from computers; and means essentially atomic picture information; it was the smallest square, or rectangle or whatever shape, depending on how the software that wrote the information to the screen was written. It was the information on the screen that could not be subdivided, thus atomic. I don't know who came up with the term, or if anyone in particular even consciously came up with it, and instead the term was just one day used and it stuck.
But as such, a pixel is entirely irrelevant to screen technology in use; the smallest dot that is no longer made up of smaller screen information is a pixel; and that's the case regardless of whether you have a CRT or an LCD, or a Plasma, or a LED screen; if you pixels that are big enough, a resolution low enough, you can see those pixels on a CRT just fine; hence the sentence, "Back when our pixels were as big as cats." Or just "Pixels as big as cats" for short. As well as "pixelated", meaning you make out a certain number of pixels, and have jaggy edges, for which we developed anti-aliasing technologies.
Now, today, given what screen technology became dominant, if your pixels don't perfectly map onto the little screen elements, whatever the proper technical term is, your picture becomes blurry, just pick a non-native resolution in a game on your PC monitor and behold the effect. Thus the term 'pixel' started to do double duty for both the virtual smallest picture information, and the physical dots on a screen, but strictly speaking the physical dots in the screen are not pixels.
And as such, CRTs can show pixels and you can see pixels on a CRT, as long as the source for the picture is digital, and its resolution smaller than the screen is capable of.
I wonder with today's technology what the most high def analog image could be created? could we have a HD image with an extremely dense shadow mask and an extra bright electron gun? hmmm
onedeadsaint There are 1080i CRTs. So it is definitely possible.
11011100DC I did not know this. very cool!
There were a number of HD CRT TVs back in the day that displayed a 1080i image and CRT PC monitors that had resolutions like 2048x1536 and 2304x1440, so at least 4K would probably be possible.
At the end of the CRT monitor era there were some pretty high resolution screens. Sony had some HD CRT TVs as well.
NoToeLong now I want to see an up close look at HD CRTs!
Let’s. *fucking.* GOOOOOOOO!
Listen man. I love you. I love your channel. You’ve taught me so much. Thank you.
If there’s another nerd somewhere on the internet that can make something as mundane as specifying the technicalities of what defines a “pixel” I don’t want them.
You’re amazing, and I appreciate you. Thank you for putting in so much effort for all of us. I’ll be part of this channel for as long as you make it man. ❤️
you did really well to condense such a complicated topic into its most concise form
In the event of the coming apocalypse we need to save this man so that he can rebuild our technologies! SAVE THIS MAN!
Did you predict the virus?
And now the master piece... Explain Plasma TV's;-)
Plasma used fixed pixels in RGB grid (except for a few Samsung models that used one shared sub-pixel color among the grid; some OLED displays had this arrangement too like original galaxy phone).
It flashes different shades of the image hundreds of times a second (typically 600 times or 10 sub-fields per frame at 60 fps) to build a single frame.
Goes to black in between frames (this helped eliminate image persistence that causes motion blur in LCD). The later models were advertised as drawing thousands of sub-fields per second, not sure if that was marketing or if the displays were actually drawing that much faster.
It used emissive pixels so each RGB element was individually lit, no backlights.
It was impulse driven, meaning each sub field was flashed on the screen for fractions of a second, your brain would see a complete image because of the persistence of vision in our eyes; LCD and OLED uses sample and hold which means the whole image is drawn, held and then the next image is drawn immediately.
Goo38
>It flashes different shades of the image hundreds of times a second (typically 600 times or 10 sub-fields per frame at 60 fps) to build a single frame.
The ones sold in Australia also ran at 600Hz, but we use a 50i TV system, so their processors would presumably have had a jumper set to generate 12 sub-fields instead of the 10 for a 60i system.
I love your editing transitions to the different tvs