Learning About Book Covers: A Touch of Grey

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From long-time visitor to TPV, Harald, a GoodReads article of an aspect of cover design PG hasn’t seen discussed elsewhere.

From GoodReads:

The Grayscale Test

Some background first. Most humans see the world via three color channels or receptors in the eye’s retina. With the Additive Color System (the one used for projected light as with TVs or LCD/LED screens and monitors), the three primary colors are Red, Green, and Blue (or “RGB”). Colors printed on paper (like paperback books) use the Subtractive Color System, which is different, although the main points below still apply in the image-making process.

[Illustration omitted]

Note that I said “most humans.” Because some have different degrees of color blindness where they have either a red/green or a blue/yellow deficit. But all humans respond instantly to differences in “contrast.” Contrast is the difference or “separateness” between two related things. But that’s a general definition. In regard to book covers, we’re talking about the contrast between the three main cover elements: main title, author’s name, and background image. Yes, there can be other elements, too (subtitle, taglines, quotes, series number, etc.), but let’s ignore those for now. If you want to catch readers’ eyes—which is one of the main functions of a book cover—then you want to increase the contrast of the main elements. And the place to start is in the pairing of the cover’s background with the title and author-name texts.

You have several options in trying to increase contrast between the background and these main text elements. You can make the text REALLY BIG. You can change the text fonts (style, weight, etc.). You can add drop shadows, panels, or outer glows. And you can play with your color selections. The latter is the focus of this post.

. . . .

Every pixel in a digital color (RGB) image—what every online (color) book cover is—can be described by the LAB Color Space model shown above. It’s a bit abstract, but what it means is that every color has three attributes: Hue, Saturation, and Brightness (aka Luminance or Lightness). The Hue is the color (is it red, purple, yellow?), and the Saturation is how “full” the color is—the farther to the outside, the “purer” the color is, the closer into the center, the grayer or weaker it is. Those two attributes are represented in the diagram above with the two “a”/”b” arrows. Don’t worry about that right now because the next part—Brightness or Lightness—is the important thing.

How light and bright is the color? Or, putting it another way, what’s the intensity of the electrons hitting the RGB phosphors on the screen you’re viewing at each point (pixel)? If full strength, it’s white or “100”. If nothing (nothing hitting the screen), it’s black or “0”. That’s the brightness range: 0-100. Every pixel of every RGB image falls somewhere along that range which is represented in the diagram by the vertical pole. That’s the “L” in LAB. And that’s all you see in a monochrome image, and that’s the key to all this.

When you do the Grayscale Test I’m suggesting, you’re stripping away the color information (the a/b stuff) from each pixel or point on the image and are left only with what’s somewhere along the 0-100 L pole. That’s Grayscale.

Why Do Grayscale Testing?

Because our eyes sometimes fool us. And color can actually confuse things. The key to having a book cover design grab someone’s attention is Brightness Contrast. And this Brightness Contrast is more easily seen when color images are turned into grayscale. To prove the point, let’s look at a one-word, large-size title in different colors. And let’s make them saturated “pure” colors. Like you see below with the same word in different standard colors on a realistic photo background.

Above left are the main RGB Primaries in their “pure” forms: Red, Green, Blue (RGB!) plus White and Black. At right are the main “Secondaries” or “Complements”: Yellow, Magenta, Cyan, plus I added an Orange and a Purple to round it out.

Squint your eyes or shrink your browser’s View size and study them. If you have normal color vision, you’ll probably notice that a few stand out (on THIS background image) with reasonably good contrast. For me, that includes the white, blue, black, and maybe the yellow. They have the most contrast with the background. But the others don’t stand out as much; they don’t have as much contrast. I’m looking at you, red, green, magenta, cyan, orange, and maybe purple. Something about those is not quite right. They kinda blend into the background. Sounds like it’s time for the Grayscale Test to see what’s really going on.

Let’s Grayscale It

Grayscale is an old designer’s trick. Like flipping a design horizontally to view it. Or squinting your eyes. But it’s probably one of the best tools for reviewing your covers as they evolve through the creative process, whether DIYing it or using a paid designer.

So this is the trick: To check your initial thoughts or feelings about your text color selections, convert the cover image to Grayscale and take another look. This is easy to do in image-editing programs like Photoshop and lots of others. Usually just a couple of clicks. I typically use the Image > Mode > Grayscale conversion in Photoshop. It does the same thing as creating an adjustment layer for Hue/Saturation and bringing the saturation down to “0.”

And here’s what you get below from the exact same images when converted to grayscale:

Aha! Looking above, isn’t it easier to see now which titles have good contrast with the background and which don’t? That is the beauty of the Grayscale Test. It confirms what you may be feeling already, even if you can’t quite pin the problem down. The Grayscale Test lays it out for you in black and white (pun intended! :).

What you’re seeing in the two cloud images above is very simple. The sky background here is a “midtone,” meaning it’s somewhere in the middle of the 0-100 L pole above. There are variations with the clouds, but the whole background is somewhere in the 40 range on average. So—and this is the imporant part—the title words that will contrast the most with this midtone background are the ones as far away from 40 on the pole, i.e. the very lightest and the very darkest ones. THOSE are your best options for THIS background if you’re looking for the most contrast using only color selection as your tool.

There’s lots more from Harald at GoodReads, including more cover examples.