Tutorial 17: preparing illustrations. Part 1: use colour
March 3, 2012
In among all the open-access discussion and ostrich-herding, we at SV-POW! Towers do still try to get some actual science done. As we all know all too well, the unit of scientific communication is the published paper, and getting a submission ready involves a lot more than just the research itself. One of the most important aspects is preparing the illustrations — indeed Matt once told me that he thinks one of the best ways to put a paper together is to start with the illustrations, then write the text around them.
[Illustrations are often referred to as "figures". I don't know how the tradition got started, but since that term also means numbers, I will try to avoid it. If I tell you "I am working on the figures for my diversity paper", you don't know if I am accumulating statistics or preparing illustrations.]
Done well, illustrations can be things of beauty as well as scientifically informative.
There are a few things to be said about preparing good illustrations, so we’re kicking off a short series on the subject. This is the first.
But the zeroth was published here a couple of years ago. Since the most important illustrations in many palaeontology papers are those of the specimens, the base you’re working from is your specimen photographs. So you might want to refresh your memory by reading Tutorial 8: how to photograph big bones before we proceed.
There are various steps in getting from a photo to a finished, publishable figure, and we’ll look at those along the way. But somewhere along the line, if you’re publishing in a conventional journal such as the Journal of Vertebrate Paleontology, you’re going to flatten your colour images down to greyscale. Postpone that step till the last possible moment.
That should be too obvious to need saying, but I’ve got it wrong myself. When I was preparing the specimen photographs for the Xenoposeidon paper, destined for Palaeontology, I flattened the images too early in the process, with the result that the greyscale versions of the figures that were included in the paper are the only versions in existence. The upshot is that if you look at the full-resolution illustrations in the unofficial supplementary information, you’ll see that the version of Figure 3 available there is greyscale, just like the one in the paper.
By the time the three of us did our neck-posture paper in Acta Palaeontologica Polonica, we weren’t quite so dumb. So although the illustrations in the published paper are all greyscale, the two that are based on specimen photographs, rather than assembled from previously published greyscale components, were prepared in full colour, then flattened as the very last process before submission. As a result, the full-resolution illustrations in the unofficial supplementary information have figures 1 and 2 in colour:
So we were pretty happy with that. But by the time we came to submit the Brontomerus description a couple of years later, we’d had a rather obvious (in retrospect) thought: just because we can’t have colour in the printed journal, does that mean we can’t have it in the PDF? We asked the good people at Acta Pal. Pol., and they agreed that we could submit colour illustrations, they’d use them in the PDF, and then flatten them to greyscale themselves for the printed edition.
Since about fifty times as many people see the PDF as see the printed journal [yes, I just made than number up out of my head], that solution suited us very well. The outcome was the the PDF has gorgeous figures like this one:
(I’m slightly sorry to be displaying all our own illustrations here, but they do make the point and frankly I like looking at them. Especially that beautiful caudal vertebra.)
Why am I making such a big deal about colour? Because colour is information, and as scientists we love information. When you flatten a colour image to greyscale, you lose information, and that should never be done without regret. It’s perfectly possible that adjacent regions of a fossil will be a different hue but the same brightness: flatten the image and the two colours look the same, but in the original you can see a distinction. That’s valuable.
So in this day and age, The Right Thing is:
- Prepare your figures in colour
- Submit them in colour
- If the journal has a printed edition (and charges extra for colour printing, as most do), tell them to flatten to greyscale.
On the other hand, if you’re submitting to an open-access journal — and you should be, if you want to be widely read — there’s a good chance that it’s online-only (as with PLoS ONE and Palaeontologia Electronica), in which case the use of colour is a complete non-issue. The only reason to prepare monochrome figures then is (as with the Taylor et al. 2011b sauropod-neck bestiary above) when you’re constructing them from pre-existing greyscale images.
Taylor, Michael P., Mathew J. Wedel and Richard L. Cifelli. 2011a. A new sauropod dinosaur from the Lower Cretaceous Cedar Mountain Formation, Utah, USA. Acta Palaeontologica Polonica 56(1):75-98. doi: 10.4202/app.2010.0073
Taylor, Michael P., David W. E. Hone, Mathew J. Wedel and Darren Naish. 2011b. The long necks of sauropods did not evolve primarily through sexual selection. Journal of Zoology 285:150-161. doi: 10.1111/j.1469-7998.2011.00824.x