What black and white forces you to see
I have taken up the habit of switching my layouts to greyscale before handing them in. It takes three seconds, it costs nothing, and it is the only test I have never managed to get around. Because when the colour leaves, it regularly happens that the hierarchy leaves with it. The title you saw first ends up on the same level as everything else, the button that jumped out melts into its background, and you have to admit the layout did not stand on its own.
People say black and white takes something away. It is exactly the opposite. It takes nothing away, it simply prevents compensating, and what appears on the grey screen is not an impoverished version of the layout, it is its structure finally made visible.
An X-ray does not show less than a photo. It shows the bone.
THE TRANSLATION
First received idea to dismantle: converting to grey is not about taking an average. If you simply added the three channels and divided by three, the result would not remotely correspond to what the eye perceives as light or dark.
The formulas used everywhere, the one from the Rec. 709 video standard for instance, give very unequal weights to the three primaries. Green counts for a little over seventy-one percent of perceived luminosity, red for twenty-one, and blue for about seven. In other words, when you look at an image, your impression of brightness comes, for more than two thirds, from a single colour.
The reason is anatomical. The cones of the retina are not distributed evenly; the ones that respond to blue are largely in the minority and they are even absent from the exact centre of the fovea. Our perception of luminosity therefore rests essentially on the cones of the middle of the spectrum. A deep blue can be vivid and remain perceptually dark, a yellow can be discreet and remain perceptually light.
The consequence is brutal and verifiable in three clicks. Two frankly different colours, a red and a green for example, can land on exactly the same grey. On screen they oppose each other, converted they merge.
A colour is not read by its hue. It is read by its weight.
THE DECISION
Which brings me to the part most people do not know: black and white was never a lack of means. It was, for decades, a system of choices.
A photographer working in black and white film carried coloured filters. A yellow, orange or red filter placed in front of the lens darkens the blue sky and brings out the clouds; a green filter lightens foliage. The photographer did not endure the translation of colours into greys, they steered it, colour by colour, before even releasing the shutter.
At the end of the thirties, Ansel Adams and Fred Archer pushed this logic to its conclusion by formalising what they called the Zone System, a method that cuts the scale from absolute black to pure white into about ten zones. The principle holds in one sentence: you decide before the shot which zone each element of the scene will fall into, then you set the exposure and the development so that it happens. What this system reveals is that a successful black and white photograph is not a photograph from which the colours have been removed, it is a photograph whose values have been assigned.
Painting knew this long before. The Japanese have a word for the balance of light and dark masses in a composition, notan, and small-format value studies, reduced to three or four greys, are a classic preparatory exercise. You settle the structure first, you add the colour after.
THE TEST
Back to my grey screen, because this business of values has very concrete consequences that have nothing contemplative about them.
The accessibility rules that today govern more or less everything published online, those of the WCAG, impose minimum contrast ratios between a text and its background, four and a half to one for body text, three to one for large type. The important point is that these ratios are calculated on relative luminance. Not on hue, not on saturation. In other words, the standard that protects the legibility of the entire web is written entirely in black and white.
There is a second, more human reason. According to the generally accepted figures, a colour vision deficiency affects about eight percent of men of northern European descent, against less than one percent of women. Which means that a piece of information carried solely by an opposition of colours, a red against a green typically, purely and simply disappears for a non-negligible share of the people who will look at it. If the same information also holds in values, it holds for everyone.
The grey test is therefore not a studio whim. It is the fastest and cheapest quality control there is.
THE PRICE
So why do so few people do it, and why does this step systematically get skipped when deadlines tighten?
Because colour is the part of the work that gets seen, commented on and approved. It is what a client looks at first, it is what they have an immediate opinion about, and it is also what makes a layout seductive in a meeting. Value, on the other hand, never gets discussed. Nobody has ever asked whether the grey of the subtitle was too close to the grey of the body text.
And yet that is where everything plays out, all the more so because colour is gifted at masking problems. A vivid flat makes an unimportant element look important; a gradient gives the illusion of a depth that does not exist in the composition. Colour does not exactly lie; let us say rather that it consoles.
That is what makes the exercise uncomfortable, and that is precisely why it has to be done.
A green that carries two thirds of an image's brightness, an orange filter screwed in front of a lens to decide the sky, an accessibility standard that speaks only of luminance, a scale of zones drawn at the end of the thirties. All of this describes the same thing from four different angles: structure comes before hue, and it goes on existing when the hue leaves.
So I will keep switching my layouts to grey before handing them in, even when it proves me wrong, especially when it proves me wrong. It is three seconds of work, and it is the only moment when an image can no longer tell me stories.
Black and white is not an image missing its colour. It is what remains when it can no longer hide anything.
To dig further. The luminance coefficients of the Rec. 709 standard, which explain the weight of green. Ansel Adams and Fred Archer for the Zone System, formalised at the end of the thirties. The WCAG recommendations for contrast ratios and how they are calculated. And any painting manual for value studies, where notan is explained better than in design books.
