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Generate maximally perceptually-distinct colors

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Generate maximally perceptually-distinct colors

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14 Dec 2010 (Updated )

Choose a set of n colors that can be readily distinguished from each other

Editor's Notes:

This file was selected as MATLAB Central Pick of the Week

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Description

When plotting a set of lines, you may want to distinguish them by color. By default, Matlab chooses a small set of colors and cycles among them, and so if you have more than a few lines there will be confusion about which line is which. To fix this problem, one would want to be able to pick a much larger set of distinct colors, where the number of colors equals or exceeds the number of lines you want to plot. Because our ability to distinguish among colors has limits, one should choose these colors to be "maximally perceptually distinguishable."

This function generates a set of colors which are distinguishable by reference to the "Lab" color space, which more closely matches human color perception than RGB. Given an initial large list of possible colors, it iteratively chooses the entry in the list that is farthest (in Lab space) from all previously-chosen entries.

Acknowledgements

Varycolor and Colorspace Transformations inspired this file.

This file inspired Plot Spread Points (Beeswarm Plot), Feedback Control Of Many Differential Drive Robots With Uniform Control Inputs, Tactics Toolbox, Simulate Control Of Magnetized Tetrahymena Pyriformis Cells, Grouped Bar Plots With Error Bars, Youden's Plot, Explore Experimental Data, Colorize Document Bar, Rgbmap Color Maps, Cubehelix Colormaps, Color Brewer: Attractive And Distinctive Colormaps, and Intuitive Rgb Color Values From Xkcd.

Required Products Image Processing Toolbox
MATLAB release MATLAB 7.10 (R2010a)
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Comments and Ratings (41)
10 Oct 2014 Miguel Lopeta  
02 Oct 2014 M S

Great function. Any plans to add in colorblind-friendly functionality?

20 Sep 2014 Timo W  
17 Jun 2014 Harshavardhan Sundar

Awesome piece of code....this helped me a lot in building intuition in a different problem I am working on..thanks a lot...

12 May 2014 Pierre M├ęgevand  
09 Apr 2014 Jim  
04 Apr 2014 Tom Gottlieb  
27 Mar 2014 Dana Engebretson  
02 Mar 2014 abc

Wonderful!

10 Dec 2013 Felipe G. Nievinski  
06 Dec 2013 Brad Humphreys

Bravo!

02 Oct 2013 Werner  
02 Oct 2013 Tim Holy

See comments from 2010 for a workaround that doesn't require the Image Processing Toolbox.

02 Oct 2013 Thierry Dalon

Requires the image processing toolbox.

29 Jul 2013 Tim Holy

Looks like it's the same idea. Thanks, I didn't know about that work.

29 Jul 2013 Jean-Yves Tinevez

Hi Tim.
How does your submission relate to Glasbey LUT?
http://fiji.sc/Glasbey and
Glasbey, Chris, et al. "Colour displays for categorical images." Color Research & Application 32.4 (2007): 304-309.

26 Jul 2013 Clara  
25 Jul 2013 Abraham Asfaw

Thanks! Learned quite a bit from your code.

23 Apr 2013 Chad Greene

Very cool idea! One cautionary comment: I'm one of the 5 to 10% of scientists who is mildly colorblind, and I cannot distinguish between colors 3 and 6 in the distinguishable_colors image shown above.

28 Mar 2013 Melissa Day

Thanks for this! And thanks to the below commenter who suggested replacing the ~ on line 115.

28 Feb 2013 Raz Shimoni

I love this function! Thank you.

16 Dec 2012 Manel Soria

Well done !

10 Jun 2012 Jonas  
04 Jun 2012 Georg Stillfried  
08 May 2012 Krista Jansen  
27 Dec 2011 John

Thank you for writinig this, it does generate an interesting set of colors that do appear to be contrasting. Would it be possible to generate one, or more, "key" colors that are highly contasted with the rest. I have about 30 lines on a figure, along with the average. While I did make the average wider, it is difficult to determine the color for the "key" line(s) using this routine.

09 Nov 2011 georg

Thanks. Suggestion: Add these lines at the beginning

if nargin < 1
n_colors=size(get(gcf,'colormap'),1);
end

(taken from jet.m) in order to allow something like

colormap distinguishable_colors

27 Oct 2011 Pete

Very neat. The usage in combination with Colorspace Transformations is especially elegant.

Change [~,index] to [tmp,index] on line 115 to work on pre-2010 versions of Matlab.

28 Apr 2011 Tim Holy

@Robert Daly: sorry I didn't see your question earlier. It's an interesting application.

I'm no expert at these matters, but I imagine you could convert to LMS color space and then set one or more of the components to zero. You'd probably then want to convert back to Lab to judge perceptual distinguishability.
http://en.wikipedia.org/wiki/LMS_color_space

Alternatively (and perhaps more guaranteed to be accurate), you could use this lookup table:
http://perso.telecom-paristech.fr/~brettel/colourmaps.html
and then convert the modified RGB values to Lab.

If you implement this, I'd be curious to see what the final result looks like.

27 Apr 2011 Bosheng

good!

31 Mar 2011 Robert Daly

Is there a colour space function that I could use with this function to find colours that are perceptually-distinct to a person with a colour vision deficiency (colour blind)? In the example I have in mind colours that are only different by the amount of red in them such as blue and purple look the same (Protanopia).

07 Feb 2011 Mihail Petrov

I've downloaded the 'colorspace' function from FEX and now it works. Great job!

07 Feb 2011 Mihail Petrov

This is an extremely useful function, but it's unusable for me because I do not have the image processing toolbox :-( Any workaround?

18 Jan 2011 Il

Excellent idea. I have one suggestion. Often times, I want to avoid not just a single background color but a set of them. For example both black and white when I have black text on white background already.

17 Jan 2011 Arthur

Nice!

24 Dec 2010 Brian Katz

This works very well. If you are using an older version of MatLab, you will need to modify line 98
[~,index] = max(mindist2);
as the ~ operator will produce an error. Simply change it to junk for example.

24 Dec 2010 Evgeny Pr  
14 Dec 2010 Tim Holy

Thanks for the feedback and suggestions, everyone. Perhaps even more important than the issue of depending on the Image Processing Toolbox, you helped me realize that there's no particular reason to restrict this to Lab colorspace; one can easily envision scenarios where the user would like to be able to have some control over what is considered "perceptually similar." So I have uploaded a new version that allows the user to supply his/her own function that converts RGB colors into whatever space "similarity" is to be judged in. Of course, one effect is that this will allow you to use the "colorspace" function.

14 Dec 2010 Matteo Niccoli

Even though I do not have image processing toolbox either, I agree this is an excellent idea and well developed code.

We should be able to use the colorspace FEX by replacing this section of code
C = makecform('srgb2lab');
lab = applycform(rgb,C);
bglab = applycform(bg,C);

with this one:
lab=colorspace('RGB->Lab',rgb);
bglab=colorspace('RGB->Lab',bg);

14 Dec 2010 Lars

From the description is seems to be one of the functions that I have been looking for many times, and the excellent rating from Brett only wettens my appetite. Alas, I do not have the image processing toolbox. Would it be possible to instead use this FEX contribution:
<http://www.mathworks.com/matlabcentral/fileexchange/28790-colorspace-transformations>

/Lars

14 Dec 2010 Brett Shoelson

Very nicely done...well written, solid, useful code.

Updates
14 Dec 2010

I have added the option for the user to supply a function handle to any desired colorspace conversion function. One application is to use the file exchange's "colorspace" set of tools. In this case, you no longer need the image processing toolbox.

07 Feb 2011

As suggested by Il, I added the ability to avoid multiple background colors.

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