My name is Michael Shumate and welcome to Logo Design Theory. Legibility is one of the rock
bottom basics of graphic design, but it’s not as easy as some people think. Let’s talk about it.
Basic Terms Before we launch into a discussion of color and contrast, let’s make sure we are
using the same language. Three terms may be used in describing any given color.
First is hue, how colors distinguish themselves from each other
in the rainbow or in the spectrum. Yellow is different from orange and from red, etc.
It is also how colors are differentiated around a color wheel.
Second is saturation, the relative richness or dullness of a color. All colors
in the spectrum are fully saturated (except at the ends, where they lapse into black). Dusty rose is
less saturated (or more neutral) than pink. Olive is a less saturated version of yellow-green.
The third term is value, which is the inherent lightness or darkness of a color. Going around a
properly constructed color wheel, the lightest color is yellow and the darkest is blue.
We have names for several dozen colors, even if we might not agree on exactly what each color is.
Of the more than two million colors that a normal human eye can discern, each one can be described
using these three terms, the way we could use three axis points to determine the position
of something in three-dimensional space or the size of something using height, width and depth.
Legibility When we can see and read what is written or perceive the elements of a picture,
we call that legibility. Legibility is a function of contrast.
Of the three qualities of color we just defined—hue, saturation and value—the one that
matters most for contrast is value. Saturation and hue hardly make a difference, especially
when distance or small size is involved. To sum up so far: legibility is a function of contrast, and
contrast is a function of value. In graphic design, nothing compensates
for a lack of legibility. No concept. No style or fashion. No coolness factor. I repeat: Nothing
compensates for a lack of legibility. Without it, no one even sees or correctly perceives your work.
This is fundamental. A good tool for accurately
describing values is tint percentage, developed in the printing industry. Halftone tints cover an
area with a small uniform grid of dots on a paper, often smaller than can be seen with the naked eye.
In a 70% halftone tint, 70% of the paper area is covered in ink and only 30% of the paper has no
ink. These halftone tint percentages should be second nature to all graphic designers.
Contrast Differential The amount of contrast between type and
its background can be calculated by subtracting the lesser value percentage from the greater.
This is the Contrast Differential. A good rule of thumb for excellent contrast is 60% difference or
more. Black type on white paper is a 100% difference, the greatest contrast possible,
whereas 35% contrast differential is minimal. Is it physically possible to read below that
threshold? Yes, of course. But is it convenient or comfortable?
No. And what is the function of graphic design? To aid communication, not impede it. Why would any
sane designers try to make their messages anything less than convenient or comfortable to read?
There is no good reason. When to Reverse and When to Surprint
If one accepts the logic of the foregoing, one would naturally think that a designer
would be safe to place black type on a background as dark as 40% or 50%.
The reality is that such type is tiresome, even oppressive, to read.
Why is that? White reflects all available light and
black absorbs it. Therefore, white is a stimulus to our visual system, and black is the absence of
a stimulus. So when we read black type on a 50% background we are seeing a non-stimulus against
a half- stimulus. On the other hand, when we read white type on the same background,
we are seeing a strong stimulus against a half stimulus. That’s why it’s inherently easier and
why reversed type, even at the minimal cutoff, seems to have better contrast.
In practical application, the cutoff for comfortable surprinting versus reversing
isn’t at the 50% mark, but at about 35%. Does that strike you as an odd number?
It might, until you remember the Golden Section, the Fibonacci sequence,
and its modern counterpart, the Rule of Thirds.
The ancient Greeks discovered a particular proportion that kept cropping up in many
different places in nature. They called this the Golden Mean or the Golden Section.
They considered it a divine ratio and sought to use it in some of their buildings and sculptures.
Leonardo Fibonacci, a pre-Renaissance mathematician, discovered a sequence of
numbers where each adjacent pair of numbers gave the Golden Section proportion, more or less.
In modern times, photographers and other students of visual arts are often instructed in the “Law of
Thirds,” which states that compositions will seem most dynamically balanced if
major elements are placed within the picture plane at a location of 1/3 or 2/3.
And so it is with the question of when to surprint and when to reverse. Surprint dark type
over backgrounds up to about 35%. Reverse light type over backgrounds from 35% to 100%.
In practical terms, there are twice as many colors over which a reversal will work compared to those
that will work for surprinting. That’s just a fact of visual reality and essential for good contrast.
I hope you can see that there are real principles we can rely on when it comes to
assuring that we have good contrast in our designs in general and in branding design in particular.
These principles are not just my opinion; they are based in the physics of human eyesight.
They are neither arbitrary nor outmoded. Anyone who ignores these principles in the name of being
more modern or creative is just spitting in the wind. If you break true principles,
all you really accomplish is to break your work. There are lots more principles we’ll discuss in
future videos that will give you a strong foundation to better branding design.
For more information, go to LogoDesignTheory.com. If you found this useful, be sure to like this
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