# Cyan on your computer **URL:** \ **Category:** Factual Questions\ **Created:** [February 20, 2006, 2:51am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280 "2006-02-20T02:51:33Z")\ **Posts on this page:** 15\ **Page:** 1
**Author:** ![budaoc](https://avatars.discourse-cdn.com/v4/letter/b/ecccb3/32.png) [@budaoc](https://boards.straightdope.com/u/budaoc)\ **Post date:** [February 20, 2006, 2:51am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/1 "2006-02-20T02:51:33Z")
Dear Cecil, I have recently heard that computers are unable to display the color cyan on their moniters, or eyes aren’t able to see it. Why is this? -Nick Tustin, Suffield CT ---
**Author:** ![Q.E.D](https://avatars.discourse-cdn.com/v4/letter/q/51bf81/32.png) [@Q.E.D](https://boards.straightdope.com/u/Q.E.D)\ **Post date:** [February 20, 2006, 3:03am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/2 "2006-02-20T03:03:46Z")
That’s news to me. I can see it, and my monitor can display it, just [fine](http://en.wikipedia.org/wiki/Cyan). ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [February 20, 2006, 3:28am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/3 "2006-02-20T03:28:29Z")
\*\*budaoc \*\*: Perhaps you can elaborate or provide the source of what you heard. Otherwise Ditto what **Q.E.D.** said. Cyan was one of the basic 16 colors available very early on for computers like the Commodore Superpet and TI-99/4A. It was available is DOS and Basic also. It displayed fine on all early color monitors I saw. Jim ---
**Author:** ![RealityChuck](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/realitychuck/32/195_2.png) [@RealityChuck](https://boards.straightdope.com/u/RealityChuck)\ **Post date:** [February 20, 2006, 3:32am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/4 "2006-02-20T03:32:26Z")
A color close to cyan is known as “non-repro blue”; if you mark up a document in it, photocopies will leave out anything written in that color. Maybe that’s what you’re talking about. ---
**Author:** ![ultrafilter](https://avatars.discourse-cdn.com/v4/letter/u/3d9bf3/32.png) [@ultrafilter](https://boards.straightdope.com/u/ultrafilter)\ **Post date:** [February 20, 2006, 3:33am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/5 "2006-02-20T03:33:03Z")
> [@Q.E.D.](#): > > That’s news to me. I can see it, and my monitor can display it, just [fine](http://en.wikipedia.org/wiki/Cyan). From your link: > [@](#): > > …indeed, CMYK printing technology cannot accurately reproduce pure cyan (100% blue + 100% green) on paper. Perhaps the OP heard this fact after a few rounds of telephone. ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [February 20, 2006, 3:35am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/6 "2006-02-20T03:35:19Z")
By the way, **budaoc** , these message boards are usually used by community members, not Cecil Adams himself. If you actually want to ask Cecil a question, try his email instead: [cecil@chicagoreader.com](mailto:cecil@chicagoreader.com) (taken from [this page](http://www.straightdope.com/index.html#askcecil)) ---
**Author:** ![Reply](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/reply/32/15952_2.png) [@Reply](https://boards.straightdope.com/u/Reply)\ **Post date:** [February 20, 2006, 3:38am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/7 "2006-02-20T03:38:37Z")
> [@ultrafilter](#): > > …indeed, CMYK printing technology cannot accurately reproduce pure cyan (100% blue + 100% green) on paper. But that’s CMYK ink used for printing, not the RGB lights used by monitors. ---
**Author:** ![Omar](https://avatars.discourse-cdn.com/v4/letter/o/f0a364/32.png) [@Omar](https://boards.straightdope.com/u/Omar)\ **Post date:** [February 20, 2006, 7:55am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/8 "2006-02-20T07:55:16Z")
> [@Reply](#): > > But that’s CMYK ink used for printing, not the RGB lights used by monitors. What I think Ultrafilter meant was that once the fact about CMYK ink was discovered, the information was passed around the grapevine (the telephone) until it became the fact of not being reproducable on the monitor. ---
**Author:** ![Scissorjack](https://avatars.discourse-cdn.com/v4/letter/s/c67d28/32.png) [@Scissorjack](https://boards.straightdope.com/u/Scissorjack)\ **Post date:** [February 20, 2006, 9:02am UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/9 "2006-02-20T09:02:02Z")
> [@What Exit?](#): > > Cyan was one of the basic 16 colors available very early on for computers like the Commodore Superpet and TI-99/4A. It was available is DOS and Basic also. It displayed fine on all early color monitors I saw. The old Sinclair Spectrum {Timex Sinclair} also had cyan as one of its 8 colours. ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [February 20, 2006, 12:25pm UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/10 "2006-02-20T12:25:44Z")
> [@What Exit?](#): > > Cyan was one of the basic 16 colors available very early on for computers like the Commodore Superpet and TI-99/4A. It was available is DOS and Basic also. The Commodore SuperPET had a built-in monochrome monitor and was incapable of displaying colour. (Well, technically it could display black and green, but those were the only two.) DOS is an operating system and BASIC is a computer programming language, and as software neither have the ability to produce coloured output except where permitted by the graphics hardware (i.e., the graphics card and monitor, or the printer). ---
**Author:** ![What\_Exit](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/what_exit/32/10652_2.png) [@What\_Exit](https://boards.straightdope.com/u/What_Exit)\ **Post date:** [February 20, 2006, 3:51pm UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/11 "2006-02-20T15:51:10Z")
> [@psychonaut](#): > > The Commodore SuperPET had a built-in monochrome monitor and was incapable of displaying colour. (Well, technically it could display black and green, but those were the only two.) DOS is an operating system and BASIC is a computer programming language, and as software neither have the ability to produce coloured output except where permitted by the graphics hardware (i.e., the graphics card and monitor, or the printer). On the Superpet, I don’t remember the monitor being built in, but I will concede it and assume I was thinking of the 64’s we had in High School Computer lab. I mentioned the software as examples of very early home computer software that had Cyan integrated. Jim ---
**Author:** ![Lumpy](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/lumpy/32/446_2.png) [@Lumpy](https://boards.straightdope.com/u/Lumpy)\ **Post date:** [February 20, 2006, 6:23pm UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/12 "2006-02-20T18:23:35Z")
Back in the days of building custom levels for DOOM, the engine used cyan as the default transparent color for sprites. (cyan=nothing). Maybe this was a widespread convention for FPSs? ---
**Author:** ![Baine](https://avatars.discourse-cdn.com/v4/letter/b/f9ae1b/32.png) [@Baine](https://boards.straightdope.com/u/Baine)\ **Post date:** [February 20, 2006, 6:33pm UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/13 "2006-02-20T18:33:54Z")
This page of optical illusions says that TVs and monitors are incapable of displaying true cyan. Go to about a third down the page to “The Eclipse of Mars”. [link](http://www.skytopia.com/project/illusion/illusion.html) ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [February 20, 2006, 7:01pm UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/14 "2006-02-20T19:01:30Z")
> [@What Exit?](#): > > I mentioned the software as examples of very early home computer software that had Cyan integrated. Yes, but my point is that the software did _not_ have cyan integrated. In DOS and most BASIC dialects, the best you could do was issue some colour-changing command with a numeric argument. The mappings of numbers to colours was handled by the hardware, not the software. Thus a command such as “COLOR 3” on one computer might change the text cyan, but the same command on another computer with a different graphics card might change it to red. As far as I know none of these early programming languages or CLIs (and possibly no present ones either) used actual colour names, such as “COLOR CYAN”. ---
**Author:** ![psychonaut](https://sea3.discourse-cdn.com/straightdope/user_avatar/boards.straightdope.com/psychonaut/32/4655_2.png) [@psychonaut](https://boards.straightdope.com/u/psychonaut)\ **Post date:** [February 20, 2006, 7:07pm UTC](https://boards.straightdope.com/t/cyan-on-your-computer/345280/15 "2006-02-20T19:07:56Z")
> [@Lumpy](#): > > Back in the days of building custom levels for DOOM, the engine used cyan as the default transparent color for sprites. (cyan=nothing). Maybe this was a widespread convention for FPSs? In my experience most games and graphics applications from the 1990s used a bright magenta colour, affectionately named “[magic pink](http://groups.google.com/groups?q=%22magic+pink%22&start=20&hl=en&lr=&safe=off&num=20&c2coff=1&)”, to indicate transparency.