This image shows a particular optical illusion that confronts us every day. Notice the difference between the black text on a white background and the reverse. With reversed type — light text on a darker background — the strokes seem bolder.
Black text on white is very familiar, so we can be forgiven for thinking it correctly proportioned. For familiarity’s sake we can say it is, but there are two effects happening here: The white background bleeds over the black, making the strokes seem thinner. With reversed type the opposite is true: The white strokes bleed over the black, making it seem bolder.
Punched, backlit letters on a sign outside the Nu Hotel, Brooklyn.
One of the most obvious examples of this is with signs where the letters are punched into the surround then lit from inside. In his article, Designing the ultimate wayfinding typeface, Ralph Herrmann used his own Legibility Text Tool to simulate this effect for road and navigational signs.
One might say that characters are only correctly proportioned with low-contrast. Although objective reality hails that as true, it isn’t a good reason to always set type with low contrast. Type designers have invariably designed around optical illusions and the constraints of different media for us. Low-contrast text can also create legibility and accessibility problems. Fortunately, kind folks like Gez Lemon have provided us with simple tools to check.
As fascinating as optical illusions are — the disturbing, impossible art of Escher comes to mind — we can design around reversed body type. On the Web, increasing tracking and leading are as simple as increasing the mis-named
line-height in CSS. However, decreasing font weight is a thornier problem. Yes, we will be able to use @font-face to select a variant with a lighter weight, but the core web fonts offer us no options, and there are only a few limited choices with system fonts like Helvetica Neue.
Reversing a logotype
For logotype there are plenty of options, but it makes me slightly uncomfortable to consider switching to a lighter font for reversed type logos. The typeface itself is not the logotype; the variant is, so switching font could be tricky. Ironically, I’d have to be very sure that that was no perceivable difference using a lighter weight font. Also, with display faces, there’s often not a lighter weight available — a problem I came across designing the Analog logo.
The logotype worked well when testing it in black on white. However, I wanted a reversed version, too. That’s when I noticed the impact of the optical illusion:
(Reversed without any adjustment.)
It looked bloated! Objective reality be damned; it simply wouldn’t do. After a few minutes contemplating the carnage of adjusting every control point by hand, I remembered something; eureka!
(Reversed then punched.)
Punching the paths through a background image in Fireworks CS4 removed the illusion. (Select both the path and the background then using Modify > Combine Paths > Punch.) Is this a bug? I don’t know, but if it is, it’s a useful one for a change!
Modify > Combine Paths > Punch in Fireworks CS4.
N.B. I confess I haven’t tested this in any other Adobe products, but perhaps you will be so bold? (’scuse the pun. :)
I grinned. I was happy. All was well with the world again. Lovely! Now I could go right ahead and think about colour and I wouldn’t be far from done. This is how it emerged:
A final note on logotype design & illusions
Before we even got to actual type for the Analog logo, we first had to distill what it would convey. In our case, Alan took us through a process to define the brand values and vision. What emerged were keywords and concepts that fed into the final design. The choice of type, colour, and setting were children of that process. Style is the offspring of meaning.
I always work in greyscale for the first iterations of a new logo for a few simple reasons:
- The form has to work independently of colour — think printing in greyscale or having the logo viewed by people with a colour-impairment.
- It allows for quick testing of various sizes — small, high contrast versions will emphasise rendering and legibility issues at screen resolutions, especially along curves.
- I like black and white. :)
I realise that in this day and age the vast majority of logos need to perform primarily on the Web. However, call me old-fashioned, but I still think that they should work in black and white, too.
Brands and display faces emerged with consumer culture during the 19th Century. Logotypes were displayed prominently in high streets, advertising hoardings, and on sign boards. In many instances the message would be in black and white. They were designed to be legible from a distance, at a glance, and to be instantly recognisable. Even with colour, contrast was important.
The same is true for the Web today; only the context has changed, and the popularity of logomarks and icons. We should always test any logo at low resolutions and sizes, and the brand must still have good contrast (regardless of WCAG 2.0) to be optimal. A combination of colour and form works wonders, but in a world of a million colours where only a handful are named in common parlance, having the right form still seems a smarter choice than trying to own a palette or colour.
A final word
This article was prompted by a happy accident followed by a bit of reading. There are many references to optical illusions in design and typography books. The example image at the start of this article was inspired by one found in the excellent Stop Stealing Sheep and Find Out How Type Works by Erik Spiekermann and E.M. Ginger. There’s also plenty of online material about optical or visual illusions you can dive into. There’s also more on how the eye processes light. Oh, and don’t forget the work of M. C. Escher!
Human eyes are amazing. In two sets of watery bags we get a wide-angle lens with incredibly sharp focus and ridiculous depth of field. Apparently our brain is even clever enough to compensate for the lag in the signal getting from retina to cortex. I know next to nothing about ocular science. Spending a morning reading and thinking about optical illusions, and contemplating my own view here in the garden office is pretty awe-inspiring. If only my photographs were as good as my eyes, illusions or no.