Change colors on range maps: red-green color-blind user issue

The maps on taxon pages use green and orange colors to distinguish between localities with and without confirmed observations, such as Texas in orange versus New England in green below:

It came to my attention today that viewers with red-green colorblindness (at least one that I know of) may be completely or nearly completely unable to distinguish the green and orange areas on these maps. Could one of these colors be modified accordingly? Thank you so much.

The colour used for Texas here looks like yellow to me, not orange, and seems pretty far removed from red; do red-green colourblind people actually have trouble distinguishing these two colours?

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This page shows an example:


I’m not completely “red-green color-blind”, only have problems with some tones of red and green, but these are completely identical for me, Texas of the same color for me as other states with filling here. Only with high magnification I can see that those pixels are more yellowish in Texas. Before now I was not aware that there are “green” and “orange” types of filling on iN maps, as they look the same for me, lol.


Here’s one simulation (from here).


Same here. Now I’m wondering how many other maps I’ve misread.


The app, Colorblind Pal, has an inspector utility that interprets colors. It’s kind of fascinating.


I am also a colourblind user, albeit not red-green. The option for a few alternate colour palettes designed for accessibility for protanopic, deuteranopic, tritanopic, or otherwise colour-challenged users would be helpful. Having more than one option can help users (even non-colourblind) optimise for what works best for them visually.


Interesting, thanks all for the links and examples. Learnt something new :)


I have deuteranopia and the colour over Texas looks exactly the same as the colour over the states further North. The only thing I can distinguish is the red squares for individual observations.
I have resigned myself to the fact that I’m going to miss stuff like this unless someone points it out.


That’s a nice site, good options in it.

If anyone wants a color blindness simulator that’s free-standing on your computer rather than web-based Color Oracle is a nice little free app that hangs out in your system tray once you open it and lets you quickly see your screen in any of the three main types of color blindness.

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Can we instead of changing colours (as some people have problems with many of them), add thick lines between different colours and maybe some lines inside, as in regular maps?


out of interest: are there also browser apps that convert the colors of websites into a better display for colorblind users?


Zarek: I have resigned myself to the fact that I’m going to miss stuff like this unless someone points it out.

I think I’ve read There are glasses now to correct some color-restricted vision. Or, Perhaps try one of the apps mentioned above?

There are apps that simulate colors to help colorblind eyes interpret differences in color they cannot see naturally? The one I checked out of curiosity is Color Blind Pal ( It’s free, so little risk to try it out:

iOS and Android

Color Blind Pal for iOS and Android helps people who are color blind see the colors around them. It also lets people with normal vision see what it’s like to be color blind.

Want to know what color something is? Now you don’t need to ask a friend - just open the app to get a descriptive name, like “bold brown”.

Want to see all colors more clearly? Use the app to shift colors that are hard to distinguish toward colors you can easily distinguish. It’ll be as easy for you to spot an orange pumpkin in a green field as it is for everyone else. Or, do you have normal color vision and want to know what someone who’s color blind sees? The app can also simulate any type of color blindness.


Haha, wow, I am colorblind and never even knew there were different colors there. They look absolutely identical.


I think adding some kind of lines or pattern might be a good way to make sure it works for people regardless of color. That said, I do think it’d also be good to try shifting the colors to be accessible to more people. If something is inaccessible for 5-10% of the users on the site (going off of colorblind statistics for the general population), that seems worthy of attention.

I also liked the idea of having options for color profiles to use like iisips said.


The problem is colourblindness is not a single spectrum issue. The point was raised by someone who has red/blue issues which is what impacts about 2/3rds of folks with colourblindness.

However, at least one person earlier in the thread has noted they have a different form, and suffer from being unable to differentiate different colours. I too have the same issue, I’m colourblind as well, but not red/blue. I can read this map just fine, but worry about a change being made in the name of accessibility that actually breaks something for other users like me where there is no existing problem.

If the site takes this up, I would encourage them to take extra time to see if they can make it a user configurable sticky option so as to not simply fix one issue and add another.


Yep, I agree that it’s a complex issue that deserves care in whatever implementation is chosen!

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This seems like a problem that is better addressed at the browser or operating system level than the website level, as you need to be able to offer a range of different color options to suit people with different types of color-blindness. There is a Chrome extension called Colorblind – Dalton which is intended to help colorblind people distinguish colors better. It has modes for three different types of colorblindness. In addition, Windows 10 and MacOS both have accessibility modes for different types of colorblindness. I’m curious why folks in this forum who are colorblind don’t use solutions like those. Are they ineffective? @igor117 @williampaulwhite17 @iisips @zarek @cthawley


To add, my proposal is if we can’t make multiple versions that would fit every person, maybe add this patterns that can be seen by everyone who can use those maps.