Perhaps this should have gone in to the post on image sizes and resolution, but I’ll talk about this separately since it seems to be something folks are curious about.
It’s a tricky thing. Everyone knows that a book is a certain size, so you think that if it’s good enough for the cover, it should work everywhere else, right?
Wrong. Allow me to elaborate.
Every designer dreads the thumbnail. It takes a beautiful image and squishes it down into this tiny thing displayable in a small area, so you don’t get the whole effect the design is supposed to have. It’s used mostly in lists of things (think of search results on Amazon.com or Google images), but could really show up anywhere.
With book covers, the thumbnail is especially challenging. You want the image to still attract attention, but how do you do this when it’s such a small thing? The obvious answer is bright, bold colors, but that doesn’t always work for a cover. Not every image lends itself to neon green or dayglow orange. To be honest, 99% of them don’t. So what do you do?
FONTS! Your title is the most important thing about the book cover. Always. Even when the other visual elements fade away, the text should remain readable. Script style fonts are pretty for sure, but how do they look when they’re small? In general, they’re hard to read. If a potential customer has to take more than five seconds to decipher the title text, you’ve lost them. Thicker, less busy fonts will always shine through on the readability scale. Most covers use these types of fonts. There’s a reason for that.
That’s not to say you should never ever use script fonts for a title. It can be done very successfully. Take this one for example. The contrast is high enough (bright orange on black) and the font is thick enough that it can work at a small size. On the flip side, like this one, the image washes out the effect of the text making it pretty unreadable when it’s little. This also has to do with the variations in lights and darks within the image itself, making it difficult to separate the photo (which is lovely), from the title. (I’d note that the author name, Shakespeare in this case, is in a non-script font, but the chosen color still makes parts of it disappear.) So there’s a few things to think about before you get flowery and swirly with your fonts.
Large versions of images generally don’t have the font problem. What’s more important here is having your resolution high enough that you don’t get weird image artifacts (example here) when you expand the image size. Basically, the computer has to generate pixels to extend the image, resulting in choppy squares of color scattered throughout the picture. The computer doesn’t care what it looks like, just that it has data to fill in spaces where the information is missing. To ensure images scale up properly, I always build them at a minimum of 300 ppi or dpi (pixels or dots per inch). It’s easy to scale down as excess info is ignored, but if you try to scale up a 72 dpi 100×100 image to a 300 dpi 400×400 image, you’re going to have serious problems. In this case, more is always better.
Like I said, whenever I build a new image, I always start at 300 dpi. If you think at some point in the future you’ll want a poster or something of that nature, I’d at least double that to 600 dpi. I create knowing that the image will eventually display as a thumbnail (it’s inevitable on the web), so I zoom way out on everything to make sure the absolute minimum information (that being mostly the title), can still be seen and understood. High contrast is another big factor (drop shadows and outer edge glow can really help you here), as opposites tend to accent each other.
While these things aren’t guarantees that your image will scale successfully, they are the best starting points to build on. Got any other tips? Post them in the comments below!