Why blue?
July 12, 2011 8:26 AM Subscribe
Why is the color of no signal to a TV now blue and why that color of blue?
I was listening to Neverwhere last night and I ran into "The sky was the perfect untroubled blue of a television screen, tuned to a dead channel." It's a riff off of Gibson's line "The sky above the port was the color of television, tuned to a dead channel," which describes a gray sky.
I know that tvs started showing a blank blue screen instead of snow a while ago and my guess is the reason is that snow was noisy to listen to when a tv hit it (although that doesn't explain why they didn't just mute when hitting an empty channel). But why blue? And why did all the tv manufacturers choose that color of blue? Why aren't there green screens when the tv is on a blank channel for some models and blue for others?
I was listening to Neverwhere last night and I ran into "The sky was the perfect untroubled blue of a television screen, tuned to a dead channel." It's a riff off of Gibson's line "The sky above the port was the color of television, tuned to a dead channel," which describes a gray sky.
I know that tvs started showing a blank blue screen instead of snow a while ago and my guess is the reason is that snow was noisy to listen to when a tv hit it (although that doesn't explain why they didn't just mute when hitting an empty channel). But why blue? And why did all the tv manufacturers choose that color of blue? Why aren't there green screens when the tv is on a blank channel for some models and blue for others?
Analog snow is caused by random electromagnetism in the atmosphere. When there's no strong station for your analog tuner to pick up, it just amplifies the stuff that's bouncing around from the sun, other stray transmissions, whatever. Random transmissions sent through the image-recreating process of analog TV looks like black & white specks and sounds like white noise.
Digital TV knows the difference between an actual station and random noise, so it doesn't try to create an image unless there's actually something there. The shade of blue is created by lighting all the blue phosphors and none of the red or green. It's handy for the screen to be some kind of color when it's on but not receiving anything, but I'm not sure why it's blue rather than white or green or red or color bars or whatever. Might've just been an aesthetic choice that manufacturers adopted as a de facto standard.
Modern TVs run firmware in the background all the time, so they're free to display a logo or anything at all when they don't detect another signal. Old CRTs didn't have that option.
posted by echo target at 8:36 AM on July 12, 2011 [7 favorites]
Digital TV knows the difference between an actual station and random noise, so it doesn't try to create an image unless there's actually something there. The shade of blue is created by lighting all the blue phosphors and none of the red or green. It's handy for the screen to be some kind of color when it's on but not receiving anything, but I'm not sure why it's blue rather than white or green or red or color bars or whatever. Might've just been an aesthetic choice that manufacturers adopted as a de facto standard.
Modern TVs run firmware in the background all the time, so they're free to display a logo or anything at all when they don't detect another signal. Old CRTs didn't have that option.
posted by echo target at 8:36 AM on July 12, 2011 [7 favorites]
Best answer: Going off echo target's explanation..
Out of the three colors a tv can display, blue is the color we (human beings) associate with calmness and tranquility. Red is very emotional color (passion, anger, etc). And while green is one of those colors that can be calming or energetic, i believe the default green of tv screens isn't the deep green of askme but of the screamingly bright and hard to look at neon green.
Blue is just the defacto color for anything (from commercials to the medical industry) where the presenter wants to you be calm and not freaked out.
posted by royalsong at 8:50 AM on July 12, 2011 [2 favorites]
Out of the three colors a tv can display, blue is the color we (human beings) associate with calmness and tranquility. Red is very emotional color (passion, anger, etc). And while green is one of those colors that can be calming or energetic, i believe the default green of tv screens isn't the deep green of askme but of the screamingly bright and hard to look at neon green.
Blue is just the defacto color for anything (from commercials to the medical industry) where the presenter wants to you be calm and not freaked out.
posted by royalsong at 8:50 AM on July 12, 2011 [2 favorites]
I don't think it has anything to do with digital tv. VCRs used this color of blue too.
posted by smackfu at 8:59 AM on July 12, 2011
posted by smackfu at 8:59 AM on July 12, 2011
In case you're not familiar with the RGB color model, by the way, here it is. Old-style CRTs have phosphors of the approximate shades of red, blue, and green depicted there, and light them at varying intensities so that the eye blends them together and perceives other colours.
I also tend to concur that it was just an aesthetic choice that was grew into a standard. Back in the '80s, my family did own one CRT-output device that used green as a "background" rather than blue, our Tandy Color Computer, one of those old-style computers that plugged into your TV set. Here's a picture of the green-background boot screen.
posted by Johnny Assay at 9:16 AM on July 12, 2011
I also tend to concur that it was just an aesthetic choice that was grew into a standard. Back in the '80s, my family did own one CRT-output device that used green as a "background" rather than blue, our Tandy Color Computer, one of those old-style computers that plugged into your TV set. Here's a picture of the green-background boot screen.
posted by Johnny Assay at 9:16 AM on July 12, 2011
It may not have anything to do with digital tv, but just like digital tv, a VCR knows when there is a signal (play) or not (stop).
I think royalsong has the best guess, though - blue is indeed considered a calming color, and that particular color of blue is probably the same color you get with an RGB value of (0,0,1). It seems like it is standard, because, all TVs are meant to produce the same picture, so, calibration aside, an RGB of (0,0,1) will look more or less the same on all TVs.
On preview: Johnny Assay's RGB chart shows that a full-tilt blue looks like that standard blue you are asking about.
posted by mysterpigg at 9:18 AM on July 12, 2011
I think royalsong has the best guess, though - blue is indeed considered a calming color, and that particular color of blue is probably the same color you get with an RGB value of (0,0,1). It seems like it is standard, because, all TVs are meant to produce the same picture, so, calibration aside, an RGB of (0,0,1) will look more or less the same on all TVs.
On preview: Johnny Assay's RGB chart shows that a full-tilt blue looks like that standard blue you are asking about.
posted by mysterpigg at 9:18 AM on July 12, 2011
Just imagine all those extra commas are oldschool tv static, and not at all a result of bad editing.
posted by mysterpigg at 9:20 AM on July 12, 2011
posted by mysterpigg at 9:20 AM on July 12, 2011
Best answer: Yeah. Primary green is kind of nasty looking, and primary red sends a "DANGER WILL ROBINSON" message, which probably isn't appropriate for a "No signal" condition.
Blue is the lesser of the three evils. If I had to wager a guess, I'd also say that blue phosphors on a CRT emit less heat than the red or green ones (although that's pure speculation). Or, perhaps they're a bit more durable and less susceptible to burn-in.
On an LCD screen, this isn't as much of an issue, as it takes basically the same amount of power/heat to display any color. In an LCD, the gizmos that make the screen bright are almost completely decoupled from the gizmos that make the screen turn colors and produce images. This is somewhat less true for LED-backlit LCDs, where the backlight can be selectively dimmed or turned off entirely in regions of the screen (but not on a pixel-by-pixel level).
The case is somewhat different for actual LED screens (ie. Video walls) and AMOLED displays. In each of these, illumination is indeed controlled on the subpixel level (ie. you've got a 3 tiny little lightbulbs for each pixel, one red, green, and blue) . If you wanted to display a static image on one of these screens, use as little power as possible, and not excessively wear out the device, I'd probably paint the whole screen in primary blue (possibly at a reduced brightness, because significant wear/energy savings can be achieved by reducing LED brightness, as opposed to CRTs, which are notoriously inefficient in this department).
posted by schmod at 9:20 AM on July 12, 2011 [1 favorite]
Blue is the lesser of the three evils. If I had to wager a guess, I'd also say that blue phosphors on a CRT emit less heat than the red or green ones (although that's pure speculation). Or, perhaps they're a bit more durable and less susceptible to burn-in.
On an LCD screen, this isn't as much of an issue, as it takes basically the same amount of power/heat to display any color. In an LCD, the gizmos that make the screen bright are almost completely decoupled from the gizmos that make the screen turn colors and produce images. This is somewhat less true for LED-backlit LCDs, where the backlight can be selectively dimmed or turned off entirely in regions of the screen (but not on a pixel-by-pixel level).
The case is somewhat different for actual LED screens (ie. Video walls) and AMOLED displays. In each of these, illumination is indeed controlled on the subpixel level (ie. you've got a 3 tiny little lightbulbs for each pixel, one red, green, and blue) . If you wanted to display a static image on one of these screens, use as little power as possible, and not excessively wear out the device, I'd probably paint the whole screen in primary blue (possibly at a reduced brightness, because significant wear/energy savings can be achieved by reducing LED brightness, as opposed to CRTs, which are notoriously inefficient in this department).
posted by schmod at 9:20 AM on July 12, 2011 [1 favorite]
Best answer: Yeah, I assume it's because it's calm "cool" color. The human eye can detect blue, but we're less sensitive to wavelengths in that range so it doesn't seem as bright. German Wikipedia has a chart (the title means "relative sensitivity").
posted by nangar at 9:35 AM on July 12, 2011
posted by nangar at 9:35 AM on July 12, 2011
Our projectors at work do this too; same color of blue. Although, IIRC, I think there's an option to upload a bitmap to display instead.
posted by sbutler at 9:52 AM on July 12, 2011
posted by sbutler at 9:52 AM on July 12, 2011
Best answer: I suspect as others that blue as choosen because it was the best choice out of Red, Blue and Green but colors do have different cultural connotations. Do these screens look differently in other parts of the world?
posted by mmascolino at 10:55 AM on July 12, 2011
posted by mmascolino at 10:55 AM on July 12, 2011
Best answer: Televisions are manufactured from components built in various factories worldwide, and those parts don't get changed out depending on where they're being shipped. As mentioned previously, television sets create images from RGB, and so it is easiest (read: cheapest) to make a television that lights up one of those three colors when static appears. Since red is a negative color in western societies (generally) and green is a negative color in eastern societies (generally), that leaves blue as a neutral color.
posted by davejay at 11:04 AM on July 12, 2011
posted by davejay at 11:04 AM on July 12, 2011
I have a Samsung that goes black with an info message about a weak or scrambled signal. So, as mentioned above, the blue screen isn't universal.
posted by hwyengr at 11:09 AM on July 12, 2011
posted by hwyengr at 11:09 AM on July 12, 2011
This is called "video muting" if you want something else to search on.
posted by smackfu at 11:43 AM on July 12, 2011 [1 favorite]
posted by smackfu at 11:43 AM on July 12, 2011 [1 favorite]
Is the same blue used as a key color for effects? ("blue screen")
[ If so then I guess the default blue screen signal can be used as an input to the effects system, or that hypothetical idea may have simply influenced the engineers' decision to choose blue as the "null" or "default" color. (Logic like that often is part of otherwise seemingly arbitrary engineering decisions, in my experience... "why not just use the same choice as some other guys have, maybe being the same will somehow be helpful to the end user"]
posted by thefool at 11:58 AM on July 12, 2011
[ If so then I guess the default blue screen signal can be used as an input to the effects system, or that hypothetical idea may have simply influenced the engineers' decision to choose blue as the "null" or "default" color. (Logic like that often is part of otherwise seemingly arbitrary engineering decisions, in my experience... "why not just use the same choice as some other guys have, maybe being the same will somehow be helpful to the end user"]
posted by thefool at 11:58 AM on July 12, 2011
The crummy graphics board on your standard VCR is probably capable of 8 colours, or 1 bit each of RGB: black, blue, green, cyan, red, violet, yellow, white.
The blue is just all blue, no red, no green. In HTML parlance it's #0000ff. Why blue? It's probably the easiest colour to look at out of the 8.
posted by Pruitt-Igoe at 12:27 PM on July 12, 2011
The blue is just all blue, no red, no green. In HTML parlance it's #0000ff. Why blue? It's probably the easiest colour to look at out of the 8.
posted by Pruitt-Igoe at 12:27 PM on July 12, 2011
thefool: blue screens can been green, pink, etc. Whatever color is least likely to be worn by the actors. It's more a vessel to separate the actor then the color importance. Color bleeding is something to be considered, but video/image technology is getting to the point where it can even manage that effectively.
posted by royalsong at 12:52 PM on July 12, 2011
posted by royalsong at 12:52 PM on July 12, 2011
Yeah, it's not digital (or even VCR) specific - it started with the first sets that used digital signal processing (reducing flickering by frame-doubling & associated scan rate increase was one of the first applications in TVs). Since the signal was being digitally processed anyway, it was simple enough to add 'extra' features like this to differentiate high-end from low-end. High-end analogue TVs have been behaving like this since at least the mid-late 90's, and it soon trickled down into cheaper sets.
It's just a combination of aesthetics, what's easy to do, and what looks best. Somewhere along the line (see above) it was decided that it was more pleasing to blank the screen on no-signal rather than display noise; blanking the whole thing (i.e. black) made it look like the screen was off, so they decided to use a colour instead; driving a combination of the 3 colour 'guns' to produce any possible colour is more complicated than driving just one; red and green both have 'angry' or negative connotations, so they went with blue (incidentally, I have seen at least one manufacturer use green on some sets - Teac?); and it's easiest to drive a colour to full-on (which results in that particular shade of blue).
posted by Pinback at 5:45 PM on July 12, 2011
It's just a combination of aesthetics, what's easy to do, and what looks best. Somewhere along the line (see above) it was decided that it was more pleasing to blank the screen on no-signal rather than display noise; blanking the whole thing (i.e. black) made it look like the screen was off, so they decided to use a colour instead; driving a combination of the 3 colour 'guns' to produce any possible colour is more complicated than driving just one; red and green both have 'angry' or negative connotations, so they went with blue (incidentally, I have seen at least one manufacturer use green on some sets - Teac?); and it's easiest to drive a colour to full-on (which results in that particular shade of blue).
posted by Pinback at 5:45 PM on July 12, 2011
I always thought it had something to do with Derek Jarman.
posted by Sys Rq at 6:48 PM on July 12, 2011 [1 favorite]
posted by Sys Rq at 6:48 PM on July 12, 2011 [1 favorite]
Another shot in the dark is that static = "malfunction", whereas blue merely means "I'm afraid I can't do that, Dave."
posted by gjc at 7:07 PM on July 12, 2011
posted by gjc at 7:07 PM on July 12, 2011
This thread is closed to new comments.
posted by EndsOfInvention at 8:29 AM on July 12, 2011