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Generate maximally perceptually-distinct colors

version 1.2 (3.42 KB) by

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

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Editor's Note: This file was selected as MATLAB Central Pick of the Week

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.

Comments and Ratings (75)

Eric Zarahn

Awesome tool. Thanks.

Mendi Barel

nice!

Peng He

Ellen

Ellen (view profile)

Thanks, it works perfectly!

Wally

Wally (view profile)

Clair

Clair (view profile)

Carmine Gno'

R S

R S (view profile)

Thanks, very useful!

Don't have image processing toolbox. Used the alternative MEX colorspace transformation (got it via File Exchange).

Good work!

Gary Mirams

Really handy, and worked first time.

binarybottle

Thank you very much!

I have ported this algorithm to Python and wrote another program to take the distinguishable_colors output and a label adjacency matrix to group colors as part of the mindboggle.info brain image software project:

https://github.com/nipy/mindboggle/blob/master/mindboggle/mio/colors.py

Cheers,
Arno

Arnold Klein

Great! Thanks!

Serge

Serge (view profile)

Whyjay Zheng

Really usefull for making a clear graph!

Whyjay Zheng

Alexei Jolkin

Useless, really, as it requires the image processing toolbox AND/OR few other scripts from file exchange.

nice and easy!!

Barbad Molaei

Barbad Molaei

Very useful

cmo

cmo (view profile)

Luca3n1

Alexander H

Stefan Karlsson

A really, really useful function. Thank you.

Igal

Igal (view profile)

Uses "makecform", which belongs to image processing => usless for those who do not have it. USing the alternative from commens requires some extra effort. Pity.

Hesam

Hesam (view profile)

Awesome function. Very useful.

Eric

Eric (view profile)

Dan

Dan (view profile)

Miguel Lopes

M S

M S (view profile)

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

Timo W

Timo W (view profile)

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

Jim

Jim (view profile)

Tom Gottlieb

abc

abc (view profile)

Wonderful!

Brad Humphreys

Brad Humphreys (view profile)

Bravo!

Werner

Werner (view profile)

Tim Holy

Tim Holy (view profile)

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

Requires the image processing toolbox.

Tim Holy

Tim Holy (view profile)

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

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.

Clara

Clara (view profile)

Abraham Asfaw

Thanks! Learned quite a bit from your code.

Chad Greene

Chad Greene (view profile)

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.

Melissa Day

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

Raz Shimoni

I love this function! Thank you.

Manel Soria

Well done !

Jonas

Jonas (view profile)

Georg Stillfried

John

John (view profile)

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.

georg

georg (view profile)

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

Pete

Pete (view profile)

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.

Tim Holy

Tim Holy (view profile)

@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.

Bosheng

good!

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).

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

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

Il

Il (view profile)

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.

Arthur

Arthur (view profile)

Nice!

Brian Katz

Brian Katz (view profile)

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.

Evgeny Pr

Evgeny Pr (view profile)

Tim Holy

Tim Holy (view profile)

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.

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);

Lars

Lars (view profile)

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

Brett Shoelson

Brett Shoelson (view profile)

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

Updates

1.2

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

1.1

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.

MATLAB Release
MATLAB 7.10 (R2010a)

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