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Tuesday
Aug202013

Five more things about colour

Last time I shared some colourful games, tools, and curiosities, including the weird chromostereopsis effect (right). Today, I've got links to much, much more 'further reading' on the subject of colour...


The provocation for this miniseries was Robert 'Blue Marble' Simmon's terrific blog series on colour, which he's right in the middle of. Robert is a data visualization pro at NASA Earth Observatory, so we should all listen to him. Here's his collection (updated after the original writing of this post):

Perception is everything! One of Agile's best friends is Matteo Niccoli, a quantitative geophysicist in Norway (for now). And one of his favourite subjects is colour — there are loads of great posts on his blog. He also has a fine collection of perceptual colour bars (left) for most seismic interpretation software. If you're still using Spectrum for maps, you need his help.

Dave Green is a physicist at the University of Cambridge. Like Matteo, he has written about the importance of using colour bars which have a linear increase in perceived brightness. His CUBEHELIX scheme (above) adapts easily to your needs — try out his colour bar creator. And if this level of geekiness gets you going, try David Dalrymple or Gregor Aisch.

ColorBrewer is a legendary web app and add-in for ArcGIS. It's worth playing with the various colour schemes, especially if you need a colour bar that is photocopy friendly, or that can still be used by colour blind people. The equally excellent, perhaps even slightly more excellent, i want hue is also worth playing with (thanks to Robert Simmon for that one). 

In scientific publishing, the Nature family of journals has arguably the finest graphics. Nature Methods carries a column called Points of View, which looks at scientific visualization. This mega-post on their Methagora blog links to them all, and covers everything from colour and 3D graphics to broader issues of design and typography. Wonderful stuff.

Since I don't seem to have exhausted the subject yet, we'll save a couple of practical topics for next time:

  1. A thought experiment: How many attributes can a seismic interpreter show with colour in a single display?
  2. Provoked by a reader via email, we'll think about that age old problem for thickness maps — should the thicks be blue or red?

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Reader Comments (9)

Thicks should be 'hot' colors, always!! (Hopefully that will settle that.)

August 20, 2013 | Unregistered CommenterBrian Romans

@Brian: Ha, I think that's probably all it will take! Sorted.

And just to be clear, assuming there's not some trans-Atlantic counter-convention here (as with seismic), I think most geoscientists use 'hot colours' to mean red & yellow — even though 'colour temperature' is the other way around.

August 20, 2013 | Registered CommenterMatt Hall

Thanks for this Matt - I think I will have to make it required reading for my students before they subject me to any more of their dubious selections of color schemes (I spelled that last bit in 'merican so that Brian would know what we're talking about).

Using "hot" colours for highs and thicks is now so ingrained as a practice that I have a hard time imagining a compelling argument to do otherwise. That, however, merely exposes my cultural bias and does not constitute any form of logical process. Is there any evidence for cultural homogeneity on this issue (i.e.: is this association between "bigness" and "hotness" hardwired into the human brain)? The popularity of certain "gentlemen's" magazines and clubs would seem to suggest so. That raises the next question - is there a gender bias in colour scale selection?

August 20, 2013 | Unregistered CommenterBurns Cheadle

@Burns: I am not sure I know how to follow you into that analysis! But I just did a quick Google image poll (very accurate and reliable data, you know) and found 25 (so-called) isopach maps with reddish thicks, and only 9 with anti-red ones. So at the very least, it seems we should always label things carefully!

Now, don't get me started on 'isopach' vs 'isochore' and 'isochron'...

August 20, 2013 | Registered CommenterMatt Hall

While I prefer 'hot' as thick and think that should be the convention, I hammer into my students to always, always, always provide a legible key/explanation for everything. During my time in industry I was amazed by the number of images I saw without distance and thickness/TWT scales!

August 21, 2013 | Unregistered CommenterBrian Romans

I have previously tried (and mostly failed) to get people to use different colour palettes for thickness (of whatever kind) and depth (of whatever kind) maps. It sometimes provides an extra clue that the hot stuff on your thickness map is not necessarily high.

I am still depressed as to how many of the standard interpretation packages don't include any perceptual palettes. Though happily Matteo is fixing that for us all.

August 21, 2013 | Unregistered CommenterRichie B

@Brian: Yes! Unfortunately it takes constant nagging. But I think software makers could help by putting that stuff right in the display.

@Richie: I've often thought it would be cool if software could 'look' at your data and suggest visualizations that emphasize subtle features. I guess this just means analyzing the histogram, maybe at different scales. But then I remember how annoying automatic wizards and helpers are... Hm.

August 21, 2013 | Registered CommenterMatt Hall

I recently did a presentation to our geoscientists about colour after doing a bunch of researching (and learning). I spent a lot of time on theory and then covered colour usage in one of our interpretation packages. I think the general realization among the audience and myself when I was preparing was that colour is quite a complex topic that few of us understand yet we use it all the time in our work. Thanks for the links to various sources of information. I'm compiling that sort of information to help educate our geoscience communitty further on the topic. It's an important one that is all-too-often overlooked.

August 21, 2013 | Unregistered CommenterScott King

I know this isn't a colour "Bar" thing, rather it is a colour "saturation" thing but it is a very interesting visual and a very different way of visual analysis Mapping Segregation and diversity of population olong racial lines and distribution. Check it out

This Amazing Map Shows Every Person in America

August 26, 2013 | Unregistered CommenterPhil Esslinger

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