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I'm working with some hardware that has RGB LEDs to indicate various states. The LEDs are limited to each element being fully on or off, so there are effectively 7 lit states (R, G, B, RG/yellow, RB/magenta, BG/cyan, RGB/white). If I want to consider (red/green) colourblind users, do I need to consider R and G as being the same LED (i.e. R=G=yellow, and magenta=cyan=white)? i.e. only use 3 possible lit states (R, B, RB/magenta)?

I'm only considering colours at this point; flashing is already being considered.

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    But if they all have different functions and (probably) positions, doesn't the distinction happen even without the colors? If I know that the first LED is the on/off state of function A, I can understand that without seeing the true color.
    – Big_Chair
    Feb 22, 2022 at 21:59
  • No, each LED can be one of several colours (R, G, B, RG, RB, GB, RGB), and different colours are being used to communicate different things.
    – askvictor
    Feb 22, 2022 at 23:52
  • If it is a critical function device like power plant control panel most possibly no any colorblind user be admitted to work with it. If it is a kind of home device maybe consider another indicator as 7-level color coding is not friendly. What is your use case?
    – Serg
    Feb 23, 2022 at 15:16
  • Instead of relying solely on color, could you also use some non-color dimension? For example, use different LED blinking patterns to represent different states? Additionally, you're concerned about colorblind users, but what about completely blind users?
    – jamesdlin
    Feb 24, 2022 at 8:58
  • I'm color blind. you can't make these limited LED color scheme work for all color blind people. do us a favor and do something without color.
    – mr guestt
    Jan 22 at 20:05

3 Answers 3

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There are some good articles written about the accessibility of traffic lights written, which I think applies equally well to LED indicators. However, the size of LED indicators and the distance that you might be viewing them from has more of an impact compared to traffic lights.

The same principles apply to physical design as it does with digital design in that you should test the actual colours in the actual environment and conditions that you would expect the users to see them rather than using reference colours.

Also, I think the actual position of the lights already provide an additional cue on which indicator is lit up regardless of the colour, so it is probably not as big an issue as you think it might be.

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    Thanks; but in this case, there are no options to add position - we have 3 LEDs, but each has a different function, not like traffic lights where the three lights are part of a group. The hardware is already locked in, and adding icon/shape to the mix isn't possible with LEDs. How do you test for this kind of thing in the wild? I don't have a ready supply of colour-blind people to ask - are there any apps/filters that provide colour-blind person's view of an IRL scene?
    – askvictor
    Feb 22, 2022 at 5:54
  • @askvictor yes, there are a lot of different tools that can simulate colour-blind vision, but generally these are for digital app rather than hardware devices. The difficult thing is to also simulate the different environmental conditions that may affect the colour in the real world, but you can start with a controlled environment and set a benchmark that you then test under different conditions. Maybe also consult eye specialists to get some specific advice in this area.
    – Michael Lai
    Jan 23 at 23:19
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You can use a online tool like color-blindness.com and upload an image of the LEDs or create a simple website of your own and use the "Emulate vision deficiencies" in chrome. You would just need some basic HTML to insert a picture or a video of the LEDs. This trick also works with any website.

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  • This is really helpful for web development but OP is dealing with hardware LEDs.
    – Laurel
    Feb 22, 2022 at 15:13
  • @Laurel yes but if he would take a picture of the LEDs and insert it in a website he could easily see what the LEDs look like for users with different types of colorblindness. I suggested using a website because it is trivial to create one and also completely free. Feb 22, 2022 at 16:04
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    Taking a photo of LEDs and then simulating color blindness seems to assume a lot about the accuracy of color reproduction.
    – jamesdlin
    Feb 24, 2022 at 8:55
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for Red/Green blindness the pairs: (G and RG/Yellow) (B and RB/Magenta) (BG/Cyan and RGB/White) will look the same. tested on two of those novelty LED plastic ice cubes. in principle we can see reds and greens, however the material difference between them all is similar to the range of grey shades; reds and browns are dark, greens and oranges are mid tones and yellow 'that other thing you call' green are bright. unfortunately, for Yellow/Blue blind folks it's a different set of combinations.

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  • Hi, and welcome to the site! Can you explain (or even link) more information on how you "tested"? And - based on the tests, you say that the combinations G, B, BG are distinguishable, contrary to the OP's assumption of R, B, RB? May 10, 2023 at 19:32

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