Peeping Map

Depending upon where you live, autumn presents us with a spectacular tapestry of colour with bright piercing yellows, soft warm oranges, and attention-grabbing reds all situated among still verdant green grasses and calming blue skies. But this technicolour dreamcoat that drapes the landscape disappears after only a few weeks. For those that chase the colour, the leaf peepers, they need to know the best time to travel.

For that we have this interactive timeline/map from It’s pretty simple as far as graphics go. We have a choropleth map coloured by a county’s status from no change to past peak, when the colours begin to dull.

All the colour

The map itself is not interactive, i.e. you cannot mouse over a county and get a label or some additional information. But the time slider at the bottom does allow you to see the progression of colour throughout the autumn.

Normally, as my longtime readers know, I am not a fan of the traffic light colour palette: green to red. Here, however, it makes sense in the context of changing colours of plant leaves. No, not all trees turn red, some stay yellow. Broadly speaking, though, the colours make sense.

And to that end, the designers of the map chose their colours well, because this map avoids the issues we often see—or don’t—when it comes to red-green colour blindness. This being the reason why a default of green-to-red is a poor choice. Their green is distinct from the red, as these two proof colour screenshots show (thanks to Photoshop’s Proof Colour option).


The choice isn’t great, don’t get me wrong. You can see how the green still falls into the shades of red. A blue would be a better choice. (And that’s why I always counsel people to stick to a blue-to-red palette.) Compare, for example, what happens when I add a massive Borg cube of blue to the area of Texas and Oklahoma—not that you have a choice, because resistance is futile.

A bit of blue

Here the blue is very clearly different than the reds. That makes it very distinct, but again, I think in the context of a map about the changing of leaf colours from greens to reds, a green-to-red map is appropriate. But only if, as these designers have, the colours are chosen so that the green can be distinguished from the reds.

As I always say, know the rules—don’t use red-to-green as one—so that you know the few instances when and where it’s appropriate to break them. As this map is.

Credit for the piece goes to the

I’ve Got the Seeing the Reds and Greens as One Blues

Today I want to highlight a print article from the New York Times I received about two weeks ago. It’s been sitting in a pile of print pieces I want to sit down, photograph, and then write up. But as we begin to return to normal, I need my second dining room chair back because at some point I’ll have guests over.

The article in question examined the rates of Covid-19 vaccination across the United States. And on the front page, above the fold no less, we can compare the vaccination rates for Covid-19 to those of the 2019–2020 flu and if you unfold it to its full-length glory we can add in the 2009–2010 H1N1 swine flu outbreak.

Front page graphics

First thing I want to address is the obvious. Look at those colours. Who loves a green-to-red scale on a choropleth? Not this guy. They are a pretty bad choice because of green-to-red colour blindness. (There’s two different types as well as other types of colour blindness, but I’m simplifying here.) But here’s what happen when I pull the photo into Photoshop and test for it. (This is a screenshot, because I’m not aware of a means of exporting a proof image.)

Reds and greens become yellows and greys.

You can still see the difference between the reds and greens. That’s good. And it’s because colour is complicated. In red-green colour blindness, the issue is sensitivity to picking up reds and greens. (Again, oversimplifying for the sake of a blog post.) Between those two colours in the spectrum we have yellow. To the other side of green we have blue.

So if a designer needs to use a red-green colour scheme—and any designer who has worked in data visualisation will have undoubtedly have had a client asking for the map/chart/whatever to be in red and green—there’s a trick to making it work.

I don’t know if this is true, but growing up, I learned that green was the one colour the human eye evolved to distinguish the most. Now for a print piece like this, you are working in what we call CMYK space (cyan, magenta, yellow, and black). Red is a mixture of magenta and yellow. Green a mixture of cyan and yellow. If you remember your school days, it’s similar to—but not the same as—mixing your primary colours. So if you need to make red and green work, what can you do? First, you can subtract a bit of yellow from your green, because that exists between red and green. But then, and this is why CMYK is different from your primary school primary colours, we can adjust the amount of magenta. Magenta is not a “pure” red, instead it’s kind of purplish and that means has some blue in it. Adding a little bit of magenta, while it does add “red” into the green, it’s also adding more blue to the blue present in the cyan. Now you can spend quite a bit of time tweaking these colours, but very quickly I can get these two options.

Reds and greens.

Great, you can still see them as both red and green. Your client is probably happy and probably accepts this greenish-blue as green, because we have that ability to distinguish so many types of green. But what about those with red-green colour blindness? Again, I can’t quite do a straight export, so the best is a screenshot, but we can compare those two options like so.

I can see the differences significantly more clearly here.

You can probably still tweak the green, but by going for that simple tweak, you can make the client happy—even though it’s still just better to avoid the red and green altogether—and still make the graphic work.

There’s a bit more to say about the rest of the article, which has some additional graphics inside. But that’ll have to wait for another day. As will clearing down the pile of print pieces to share, because that keeps on growing.

Credit for the piece goes to Lazaro Gamio and Amy Schoenfield Walker.

I’ve Got the Subtlest of Blues

As I prepared to reconnect and rejoin the world, I spent most of the weekend prior to full vaccination cleaning and clearing out my flat of things from the past 14 months. One thing I meant to do more with was printed pieces I saw in the New York Times. Interesting pages, front pages in particular, have been piling up and before recycling them all, I took some photos of the backlog. I’ll try to publish more of them in the coming weeks and months.

You may recall this time last month I wrote about a piece from the New York Times that examined the politicisation of vaccinations. I meant to get around to the print version, but didn’t, so let’s do it now.

Now in print…

I noted last time the use of ellipses for the title and the lack of value scales on the x-axis. Those did not change from the online version. But look at the y-axis.

For the print piece I noted how the labels were placed inside the chart. I wondered at the time—but didn’t write about—how perhaps that could have been a technical limitation for the web. But here we can see the labels still inside. It was a deliberate design decision.

Keeping with the labelling, I also pointed out Wyoming being outside the plot and it is here too, but I finally noted the lack of a label for zero on the first chart. Here the zero does appear, as I would have placed it. That does make me wonder if the lack of zero online was a technical/development issue.

Finally, something very subtle. At first, I didn’t catch this and it wasn’t until I opened the image above in Photoshop. The web version I noted the use of tints, or lighter shades, for two different blues and two different reds. When I looked at the print, I saw only one red and one blue. But they were in fact different, and it wasn’t until I had zoomed in on the photo I took when I could see the difference.

I’ve got the blues…

The dots do have two different blues. But it’s very subtle. Same with the red.

So all in all the piece is very similar to what we looked at last month, but there were a few interesting differences. I wonder if the designers had an opportunity to test the blues/reds prior to printing. And I wonder if the zero label was an issue for developers.

Credit for the piece goes to Lauren Leatherby and Guilbert Gates.

New True Blue

Today’s post is not about data visualisation per se, but rather an element of it: colour. Two weeks ago, the Times reported on the creation of a new artificially made pigment of the colour blue.

This screenshot from the article doesn’t do it justice. Click through to see the large photo.

You can read the article for the full details, but the new pigment contains yttrium, indium, and manganese. Combine the symbols for those elements, Y, In, and Mn, and you have YInMn Blue. In particular, the colour exhibits permanence and thus does not fade, say when mixed with water.

And it’s non-toxic, because for those who don’t know, some of the most popular paint colours in history have turned out to be toxic. White paint? Made with lead. Some of your bright, rich reds? Turns out cadmium can kill. And with blues we often see cobalt or chromium as part of the mixture and, guess what, they’re both toxic. But not YInMn.

Last summer, the Environmental Protection Agency (EPA) approved the pigment for commercial use. And so we can begin to use it in oils and watercolour paints. (The EPA had approved its use for industrial purposes back in 2017. Check out this article for an image of the blue used to make an electric guitar.)

For data visualisation and design purposes, for web stuff, colours work differently. The blue in the screenshot above from the Times article, that is made by photons emitted by your computer or mobile phone. Whereas, when you view that pile of pigment in person, or a guitar body, or a painting—all in person—what you are seeing is the absorption and reflection of light waves striking the objects. What you see is the portion of the light wave that is reflected, i.e. not absorbed, by the object.

So it’s possible that we could see YInMn Blue as the basis for a paint used in printing and therefore tints of it used to make a choropleth map of freshwater availability. But if your work is strictly digital/web based, this probably won’t make too much of an immediate impact.