EEVblog #224 red green blindness problem - Page 1
Forum section: electronics / general

author: manolis
author_rank: Newbie
timestamp: December 02, 2011, 11:29:21 pm
content: Hi,I just wanted to give some, maybe unexpected, feedback on the 3rd part of the power supply series. It is nearly impossible to distinguish the traces on the oscilloscope, for someone with a red green color blindness. (both lines look like the same yellow greenish color) Am I the only one having this problem? If not I would like to suggest using maybe yellow and blue for future multichannel oscilloscope action.So longManolis

author: EEVblog
author_rank: Unknown
timestamp: December 03, 2011, 01:18:04 am
content: I don't think you can change the colours. They are matched to the front panel and probe colour coding.Dave.

author: ablacon64
author_rank: Frequent Contributor
timestamp: December 03, 2011, 03:50:59 am
content: Maybe this is something the manufacturer should be informed about.

author: IanB
author_rank: Super Contributor
timestamp: December 03, 2011, 06:31:49 am
content: This is an aspect of user interface design that is often overlooked. Typically there should be some other visual cue in addition to colour, such as varying line style or shaped markers/labels on the traces.

author: EEVblog
author_rank: Unknown
timestamp: December 03, 2011, 06:45:58 am
content: Does everyone go colour blind the same way?Stupid question??Sorry, I know absolutely nothing about it.Dave.

author: Chet T16
author_rank: Frequent Contributor
timestamp: December 03, 2011, 07:07:28 am
content: There's a couple of different types, there's an android app that simulates them using the camerahttps://market.android.com/details?id=com.SeewaldSolutions.ColorBlindnessSimulator

author: IanB
author_rank: Super Contributor
timestamp: December 03, 2011, 07:11:33 am
content: http://www.colblindor.com/2010/03/16/red-green-color-blindness/Red-green colour blindness is inherited and present from birth. About 8% of men and 0.5% of women suffer from some kind of red-green vision deficiency.

author: benemorius
author_rank: Regular Contributor
timestamp: December 03, 2011, 08:04:53 am
content: With some 4% of the population being affected, it may indeed be worth taking in to consideration. It's the most common type of color blindness, but I had no idea the rate was so high.The suggestion of using the yellow and blue channels for a 2 channel setup seems ideal since that would also allow the full sampling rate compared cutting it in half while using channels 1 and 2.

author: mobbarley
author_rank: Regular Contributor
timestamp: December 03, 2011, 08:18:33 am
content: 8% is pretty large! I only suffer from what is probably computer screen induced myopia.I hate computers

author: ejeffrey
author_rank: Super Contributor
timestamp: December 03, 2011, 10:05:05 am
content: Red-green color blindness is by far the most common, and I think it would be worthwhile for scope manufacturers to select default colors that would be visible to those people. I don't know how hard this is -- it may be difficult to find 4 colors that are highly distinguishable under a range of lighting and viewing conditions both on the screen and the probes.In any case, I really think there should be a provision to change the on-screen colors for anyone that can't distinguish the defaults easily. If not matching the probes is a problem it is a simple enough matter of using some colored stickers.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 03, 2011, 12:28:46 pm
content: You are no worse off than a person with an analog Oscilloscope,where you can get any colour you like,providing it's green!(or blue on some 'scopes)VK6ZGO

author: saturation
author_rank: Super Contributor
timestamp: December 03, 2011, 01:14:39 pm
content: Most new generation DSO have options to reset the colors, unlike an analog scope. On the Rigol 1052e series for example, one of the 'skins' maybe one you can see better to distinguish multiple traces on a scope. The default colors should be viewable: yellow, blue and purple for ch 1, 2, and math respectively which I estimate can be seen by even the worse variant, the protanope.Normal is upper left, you should see a green tinged 2 in a red-pinkish background of dots.

author: Mechatrommer
author_rank: Super Contributor
timestamp: December 03, 2011, 02:12:38 pm
content: i guess the why yellow-blue mystery has been answered. thanks to OP for highlighting this up.

author: aargee
author_rank: Frequent Contributor
timestamp: December 04, 2011, 07:03:55 am
content: It used to be (still is??) that colour blindness ruled you out of a job in electronics/electrical work.I remember doing this as a basic test with Telecom in the early 80's.- Rob.

author: BravoV
author_rank: Super Contributor
timestamp: December 04, 2011, 07:51:13 am
content: Quote from: aargee on December 04, 2011, 07:03:55 amPretty confident still applies to bomb squad, you know, those cables at the bomb timer ... <snip>... BANG !

author: ejeffrey
author_rank: Super Contributor
timestamp: December 04, 2011, 09:31:21 am
content: Quote from: aargee on December 04, 2011, 07:03:55 amI know several people who work in electronics and are color blind. It isn't that serous of a problem most of the time. I can see it being a bigger issue if you are a field technician for the phone company working on bundles of hundreds of color coded twisted pairs. For your a desk worker doing electronics design and whatnot it is fairly easy to work around.

author: Zero999
author_rank: Super Contributor
timestamp: December 04, 2011, 06:37:54 pm
content: Quote from: IanB on December 03, 2011, 07:11:33 amOne thing that most people miss is there's a huge range of different levels of colour blindness. On the one extreme some people have no cones at all which means they have no colour perception at all and generally poor vision, then there are those who only have one colour cones, say green who have normal visual acuity but no colour vision to those who have a two colour cones and those with slight colour deficiency.I have deuteranomaly which is not red-green colour blindness in the way most people probably perceive it. I have the full complement of red, green and blue cones so can distinguish between different colours quite well most of the time - reading resistor colour codes or distinguishing between different colour wires has never been a problem for me. It's just the peak response of my green colour cells is slightly shifted towards the red end of the spectrum which can make identifying different shades of green, yellow, orange and brown difficult under some lighting conditions. If I look at a rainbow, the green to red part will be appear closer together than it should and the green-violet further apart than the should. This means that although y ability to distinguish between shades in the red-gree may not be so good, I may be better in green-blue end of the spectrum than someone with normal colour vision.

author: slateraptor
author_rank: Frequent Contributor
timestamp: December 04, 2011, 07:55:22 pm
content: Oh, crap. So just went into hypochondriac mode.

author: IanB
author_rank: Super Contributor
timestamp: December 04, 2011, 09:46:32 pm
content: Quote from: slateraptor on December 04, 2011, 07:55:22 pmWhy did you just post a picture of a plain grey card?

author: Wartex
author_rank: Frequent Contributor
timestamp: December 04, 2011, 10:30:56 pm
content: Quote from: ejeffrey on December 04, 2011, 09:31:21 amIANAL but labour laws prohibit colorblind in working in industries where work/products affect safety of others. You wouldn't want a PLC wiring harness made by a colorblind person to be used in a power plant or something.

author: Zero999
author_rank: Super Contributor
timestamp: December 05, 2011, 06:42:59 pm
content: Quote from: Wartex on December 04, 2011, 10:30:56 pmI would have no problem with that whatsoever.If the wireman's colourbliness caused a problem, it's the engineer's fault for designing the panel so cable colours are important for electrical safey.Where I work we use wire and terminal numbers, colours are only used in accordance with the electrical code. Even if the technician is not colourblind, it's bad to rely on colour because the lighting may distort colours anyway; this is especially true in locations lit by mercury or HID lighting.

author: ciccio
author_rank: Frequent Contributor
timestamp: December 05, 2011, 08:35:41 pm
content: With age going up I developed a slight form of colorblindness, that the ophthalmologist declared "futile and of no conseguences" and treated me as a fool because I was passing his (her) tests, so I had measurable problem..My problem is that, if I don't have a strong lightning and sometimes a small magnification, I have problems in reading resistor color codes. Every strip is gray!!! Same problems with ICs that are laser marked: brown on gray is not OK.A simple lighted magnifier et voilà: everything is ok.The experts above can give me some indications?Thanks and best regards

author: IanB
author_rank: Super Contributor
timestamp: December 05, 2011, 09:17:21 pm
content: Quote from: ciccio on December 05, 2011, 08:35:41 pmMake sure you have good quality lighting--incandescent preferably. Fluorescent and LED lighting can be really bad for colour rendition. Switching out incan bulbs for CFLs can easily make you think your eyesight is failing.You might like to get a colour chart like the ones used for monitor or printer calibration and look at it under different lighting sources. Pick the lights that do the best job of making all the colours look different and identifiable.

author: benemorius
author_rank: Regular Contributor
timestamp: December 05, 2011, 10:35:26 pm
content: CRI is what's important with regard to colors and lighting. It's not a perfect rating system, and marketing departments do try to cheat as you'd expect, but it's the best thing you have to go by short of actually trying the lights out. A light source with a higher CRI emits a more complete spectrum of light and allows better color rendition. For a perfect CRI of 100, you do pretty much have to go with incandescent lights. Their CRI is 100 by definition. However, if you hate yellow light as much as I do then that isn't much of an option. Ain't no such thing as a 6500k incandescent light.Fluorescent lighting phosphors have been improving and you can find lights with a CRI in the 90s now, which is very good. You can easily get them with a CRI below 60 if you aren't paying attention though, so it's important to check the specifications. The worst (and often the most common) fluorescent lights out there will actually have gaps in their emission spectrum where they emit no light of a given frequency at all. As IanB pointed out, those can drive even someone with normal vision crazy.Checking the light source yourself with a color chart sounds like an excellent idea when it's that important. You end up collecting the same data that CRI testing was meant to collect, but you're doing it yourself with your own two eyes, and you're checking a much more complete spectrum than the handful of samples dictated by testing procedures.

author: vk6zgo
author_rank: Super Contributor
timestamp: December 06, 2011, 01:09:37 am
content: Quote from: ciccio on December 05, 2011, 08:35:41 pmHave you tried looking at some OLD resistors to see if the problem is as pronounced?What I have noticed is that modern resistors have paint where,brown,orange & red are not very much different.I thought it was my eyes until I looked at some oldies in my junkbox--all the colours were distinctly different.It costs more to use better paint,so the bean counters found a cheap cruddy source & went with it.The first time I saw laser marked ICs,I thought that they had overheated & burnt the white paint!VK6ZGO

author: PetrosA
author_rank: Frequent Contributor
timestamp: December 06, 2011, 03:06:54 am
content: I've never heard of color blind people not being allow to work as electricians here in the US. I have red-green issues like Hero999 and I have to be careful with black and green wires in low light conditions, depending on the manufacturer. For some reason we haven't adopted the green/yellow stripe standard for ground wires in N. America nor is there a "safety" green used for insulation (I would be very much in favor...).I am now on my third LED flashlight, not because the old ones stopped working, but because the CRI keeps getting better and that's important in my work.Edit to add: I have heard that up to 15% of men have some degree of red/green deficiency. It's always been something I've tried to be aware of in any design work I did.

author: ciccio
author_rank: Frequent Contributor
timestamp: December 06, 2011, 12:54:05 pm
content: Quote from: vk6zgo on December 06, 2011, 01:09:37 amWell, the older resistors I have in stock are usually bigger in size (1/2 W against 1/4 W), and the body color is darker.The new ones have less defined color stripes (orange = red, etc), and I believe that the paint thickness is very small, so colors are a little "smeared", but everything goes OK with more lighting and a little magnification..Thank for the suggestions.Best regard

author: robrenz
author_rank: Super Contributor
timestamp: December 06, 2011, 01:21:05 pm
content: Quote from: EEVblog on December 03, 2011, 01:18:04 amUse channel 1 and 3 (yellow-blue) instead of 1 and 2 (yellow-green)

author: Excavatoree
author_rank: Frequent Contributor
timestamp: December 06, 2011, 03:05:51 pm
content: Two random and late thoughts:When I designed harnesses for school busses, we had to specify that the wires be marked with numbers in addition to the color codes. (even in the case where the number wasn't a circuit number, but merely a color indicator - 55 is red, for example.The CAD program PRO-E uses red and green to indicate sides of planes - one of my co-workers had to change his colors, as he couldn't distinguish between the two.

author: saturation
author_rank: Super Contributor
timestamp: December 06, 2011, 03:14:54 pm
content: Its possible to help some variants see better with color shifting lenses:http://www.colormax.org/YMMV, but what have you to lose if you have RG deficiency?

author: baljemmett
author_rank: Unknown
timestamp: December 06, 2011, 03:21:31 pm
content: Quote from: Excavatoree on December 06, 2011, 03:05:51 pmWhen I tried gEDA's schematic capture program a while back, I'd been struggling for ages to get wires connected to symbols properly until I noticed it showed a little red dash at the connection points -- it was practically invisible to me against the black background, so I'd been trying to wire things up to the wrong places!(Now, I would have researched the commands I needed to give it to change the colours to something more compatible with my eyes, except by that point I'd also given up on trying to get useful HP-GL output from it too so just switched packages...)

author: Bored@Work
author_rank: Super Contributor
timestamp: December 06, 2011, 04:37:23 pm
content: Quote from: baljemmett on December 06, 2011, 03:21:31 pmYou are glad you didn't. The gEDA developers made a classic mistake, thinking every user is a programmer ... Colors are changed by changing a script that is executed at startup by gEDA's build-in scripting language interpreter. Located in some non-obvious place.What is even worse, they settled on an obscure scripting language, Scheme. Yes I know, Scheme give long beard CS types and users of a certain editor a hard one. But really, for PCB designers? People who just want to do their PCB, without a master in CS just to change the color of that thing. I am sure you can do wonderful things in the startup script with that scripting language, and it is sooooooooo flexible, but who the f... wants that?

author: Zero999
author_rank: Super Contributor
timestamp: December 06, 2011, 05:48:00 pm
content: Quote from: PetrosA on December 06, 2011, 03:06:54 amMy colour deficiency is nowhere near that bad.By the sounds of it you lack green receptors alltogether or they're reduced in number. I don't have any porblem with colours in real life, it's just I fail some colourblindness tests which I find frustrating because people think I'm worse than I am.

author: baljemmett
author_rank: Unknown
timestamp: December 06, 2011, 10:01:46 pm
content: Quote from: BoredAtWork on December 06, 2011, 04:37:23 pmAye, there was some other setting that I'd changed similarly. When I found out that was the only way to change the colours I couldn't help but think someone had perhaps missed the point of a GUI... Seriously, surely it's obvious that the right way to do this is a nice colour chooser widget of some sort next to a small example section of schematic so you can see how your selection will work out. (Yeah, I know, 'patches welcome', etc.)Quote from: BoredAtWork on December 06, 2011, 04:37:23 pmHeh; as a clean-shaven CS type and user of the other certain editor, I had much the same reaction. I mean, I may be a pervert right enough, but I'm notsick!

author: Bored@Work
author_rank: Super Contributor
timestamp: December 06, 2011, 10:24:46 pm
content: Quote from: baljemmett on December 06, 2011, 10:01:46 pmMy experience with submitting large, non-trivial patches to open source projects is that they are usually not welcome and are rejected. No, I haven't tried to submit a patch to gEDA, so I don't know if they are the exception.If you are lucky an open source project rejects your large patch but kindly allows you to resubmit it after you jumped through all kinds of hoops. Like signing a contributor agreement, porting your code back and forth to development, staging, testing and whatnot branches, all at the same time, and insisting you follow coding rules which, on the other hand, aren't at all taken serious by the regular contributors in the existing code base.QuoteAlso known as the 1TE, the one true editor.

author: Unknown
author_rank: Unknown
timestamp: December 06, 2011, 10:42:59 pm
content: While this sucks from a user experience perspective, I can understand the developer side as well. You start by implementing support for configurable colors. For testing, you just write some scheme by hand. You'll implement the color configuration UI later, except that something more important came up. For most users, a dialog for configuring colors isn't exactly at the top of their wish list. Open-source projects by gEDA have limited resources, both in time and motivation.Quote from: BoredAtWork on December 06, 2011, 10:24:46 pmIf you look at the bigger picture, i.e. that the stability and maintainability of the whole code base is more important than a single feature, they may have a valid point there. Merging random patches without regard for quality or consistent style is not a good long-term strategy. It's very hard to evaluate someone else's work if they just replaced an entire subsystem. Small incremental changes are much easier to verify. Of course in some cases the answer is politically motivated, i.e. "I don't like the idea and hope you go away".

author: baljemmett
author_rank: Unknown
timestamp: December 06, 2011, 11:18:57 pm
content: Quote from: alm on December 06, 2011, 10:42:59 pmOh, indeed; with my professional hat on it's perfectly understandable -- although since I write commercial closed-source stuff I don't have the luxury of leaving UI out of a release because I didn't have an itch to scratch (but unless the UI is going to influence the implementation significantly, it doesn't get written until later.) That's not such a problem in the open-source world where 'release' is a rather more nebulous concept.(I should probably add that I wouldn't have found messing with the config file and playing guess-some-colours-that-will-work to be a hugeproblem, per se, but since I couldn't find a working lash-up of print configuration and filters to get a decent A3 plot out of it I didn't see much point in sticking around -- and it was anyone's guess which package was at fault with that issue.)

author: baljemmett
author_rank: Unknown
timestamp: December 06, 2011, 11:25:36 pm
content: Quote from: BoredAtWork on December 06, 2011, 10:24:46 pmThankfully I think my experience has been with either small, trivial patches or more-receptive projects; mind you, in some cases the patches I sent just stung the relevant maintainers into doing a better job themselves. Either way, mission accomplished! I spent several years watching Wine development though and, well, *shudder*...(Not that I can claim to be much better. I think a project that I allegedly maintain has a couple of patches that have been rotting in the queue for a year or two now; really must do something about that before its tenth anniversary.)QuoteGood man!

author: Zero999
author_rank: Super Contributor
timestamp: December 08, 2011, 08:58:09 am
content: Quote from: BoredAtWork on December 06, 2011, 10:24:46 pmOr you could cut the BS and create your own fork. If it's popular enough, the changes will be eventually be accepted by the project.

author: Excavatoree
author_rank: Frequent Contributor
timestamp: December 08, 2011, 05:01:03 pm
content: Quote from: Hero999 on December 08, 2011, 08:58:09 amYou mean create one's own "forking version?"(sorry, I couldn't resist)