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Based on this question I've been racking my brain trying to find a color scheme for journal publications that is color blind friendly and that I actually like. I've tried color brewer and other sites, and they all seem to give color schemes that are just one pastel collection after another.

I tend to only make simple x-y plots with perhaps 3-5 data series (no major data crunching here). "Old" me would have loaded up a more traditional scheme with black/red/blue/green. "New" me wants something better, but all I can find are color schemes that look so pastel. In my field, traditional is the norm, so I don't want to be too outlandish.

The best I can come up with is using a more traditional color scheme, but with different line types (dashed, solid, etc) and data points (circles, squares, etc.) to distinguish data. Can't recall where I saw this but this is one strategy for making more color blind friendly plots.

Is there a non-pastel or non-wild color scheme I could use?

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    You don't find the single-hue blue and green patterns suitable? I wouldn't say they're "pastel" at all. . . . – aeismail Feb 26 '15 at 15:29
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    Are these too 'pastel' for you too? mrao.cam.ac.uk/~dag/CUBEHELIX There are many parameters you can tweak; if you raise the hue on the generator mrao.cam.ac.uk/~dag/CUBEHELIX/cubetry.html they definitely don't look pastel to me. – Federico Poloni Feb 26 '15 at 15:36
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    What's wrong with using a more traditional color scheme, but with different line types (dashed, solid, etc) and data points (circles, squares, etc.) to distinguish data that you mention in the question already? That's what I've been doing (example here, it does use a colorset that pgfplots calls exotic, though). – gerrit Feb 26 '15 at 16:37
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    @aeismail I haven't tried making a simple line plot with single-hue color combinations, but maybe it's worth an attemp. – che_kid Mar 1 '15 at 1:35
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    On more reflection, I think my aversion to anything Pastel-ish or wild or whatever you call it, is that they remind me too much of Excel. I don't want plots that look like they were made with Excel. Not good. – che_kid Mar 1 '15 at 1:37
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If possible, try to use other visual indicators (line shapes, point markers etc). AFAIK there is no "safe" color scheme for all color-blind; at best, you can address some most common (eg. red=green).

But additionally:

  • displays are of various color quality (especially in projectors!),
  • printers are of various color quality,
  • many people print papers with B&W printers.
  • 8
    +1 for "B&W printers" -- I'm pretty sure a black-and-white-safe diagram is inherently safe for any form of colorblindness. – cpast Feb 26 '15 at 20:11
3

Nice question. Design priorities can help a lot here. Let's say your priorities are (descending order):

  1. Communicate the chart lines clearly
  2. Make it color-blind friendly
  3. Avoid using boring color palettes

Here's how I might design for these priorities (you'll have to pick your own way):

#1: Use solid, bold, colorful lines for the data, fade the axes and titles to highlight the data. Avoid dashed and dotted lines because they break up visual flow (remember, color-blind is a lower priority so let's solve that later).

#2: We decided not to use dashed/dotted lines above, so (a) use markers to distinguish different data series for the color blind. (b) Avoid using legends (this is a pet peeve for me) because they force reader's eye to dart between the legend and the data. Instead, put series names right next to the lines so it's clear. This will also help color-blind reading.

#3: Now that #1 and #2 are satisfied, you can move onto the subjective palette design. There are tons of palettes available, just pick one.

Here is one result of this process, using a contemporary palette that includes the Pantone color of the year:

chart

  • re. putting series names next to the lines, what do you do if two lines end in a proximate value, and their names overlap? – Dvir Adler Mar 3 '15 at 19:36
  • @DvirAdler You can always add a legend that says O is USA, X is Turkey etc. – PixelSnader Mar 23 '16 at 12:19
3

Cynthia Brewer has done a great deal of work in color arrangements, namely for cartography, which can take color blindness into consideration.

She has a website which allows you to select from several parameters, including color blindness, to create a limited set of colors for multiple situations: ColorBrewer. The color selection is put in the context of maps, but the colors work equally as well under other situations.

  • 2
    The question says the OP has already tried ColorBrewer. – AlexC Mar 4 '15 at 17:17
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Here is – at least theoretically – in some sense the most color blind safe 7-color set that is forced to include black and white, in no particular order:

enter image description here

It is pretty much the same as a larger 16-color set I made but modified according to feedback from 7 persons with deuteranomaly and 2 persons with protanomaly. It is the maximum minimum CIEDE2000 color difference (14.8) solution in sRGB for normal vision and for simulated deuteranopia and protanopia, with 25 % white mixed into 75 % color in linear intensity scale to simulate small markers and thin lines on a white background. In HTML notation the colors are:

#000000, #ffffff, #ff1e00, #ffb49d, #22a8be, #36fa0e, #df0095

or as floating point numbers as they were optimized by Differential Evolution:

0, 0, 0,
1, 1, 1,
1.000000, 0.115928, 0.000000, 
1.000000, 0.705698, 0.616256, 
0.132765, 0.657791, 0.743285, 
0.211692, 0.980599, 0.053187, 
0.875940, 0.000000, 0.583689

These are quite usual colors, but for a reason. I do not know how much printing in CMYK deteriorates the set. A number of color blind people commented that there should be a double code, for example with shape, texture, or literal, in addition to color. This would also help people with achromatopsia (total color blindness). I considered making sure that the colors look the same in grayscale, but unless the colors were actually shades of gray it would probably not work for all forms of achromatopsia if the affected people have varying sensitivies for red, green, and blue.

2

I know you said you've used Color Brewer before, but you might also consider downloading Color Oracle. It's a program that was developed by Bernhard Jenny and Nathaniel Vaughn Kelso, both of whom are rockstars in the Cartography world.

The program is designed to show you how a colorblind person would see your plots. So if you determine the best color scheme, you can see it how someone with Deuteranopia, Protanopia, and Tritanopia would see your plots.

Generally for articles, the accepted convention for any kind of graphic or table is black and white.

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