So, you’ve got your cover, or at least an idea for one, right? No vague clouds in the sky with bold black font for you, you’ve got a COVER, baby! Right? So now what? What’s next? We need to discuss image resolution.
This is often to referred to as dpi (dots per inch) when it comes to printing. Basically, the more dots per inch you have, the larger and more detailed your image is going to be. The less dots per inch you have, the less detailed. Ever seen one of those really badly pixelated vanity press covers?
This is because the person in question knew diddly-squat about image resolution. The big rule of image resolution is this:
What you see on a website is not what you want to print.
Computer monitors and website browsers display at a far lower pixel rate than a lush print of a digital painting. Most of the time, if you examine an image on a website, its image resolution is anywhere from 72 to 100 pixels per inch. The average printer prints at 300 dpi; and it goes up from there for higher quality stuff.
So, if you find a stock picture of some pretty clouds online (which you better not, because that makes for a crappy cover) and try to print it out at 300 dpi, that 72 dpi is all that image has. No more. So the printer will try to fill the holes by giving you blocky pixelation. This also happens with image programs like Photoshop: if you open a new document with 300 dpi and try to stretch those happy clouds to fill the space, you will get blurry blocks. The general rule of thumb is: it can always get smaller, but never bigger. You can shrink things, but not blow them up.
Conversely, if you ever see an image online displayed at 300 dpi, it’s probably four times as big as your monitor. I’ve seen this happen sometimes when people have uploaded their book covers for display; again, because they know nothing about digital imaging.
So, your tips:
1. If your book is getting printed out, your image should be a minimum of 300 dpi. If you’re still miffed about image resolution: Google it. Nobody ever got hurt educating themselves in the Information Age. Most vanity publishers don’t care what crap you send them, but if you’re self-publishing, most packagers will give you image specs on their guidelines. For example, Xlibris says “Each file should be in the TIFF (.tif) or JPEG (.jpg) file formats, in CMYK color mode, with at least 300 dpi resolution.” (CMYK mode is a color mode specifically meant for printing; most of what you see online is meant for computer monitors in the RGB color mode.)
2. If your book is entirely electronic, stick to 72 – 100 dpi. This is the size my cover will be, so that it looks nice and crisp in a zoom, but won’t be so huge that someone on a mobile will never be able to see all of it at once. Now, this is not to say that I don’t have a high resolution image (i.e., something at 300 dpi), because one never knows when I might need it. If I suddenly found myself going to a sci-fi convention, I could make myself some nifty bookmarks or business cards with the cover that would require a high-resolution image. It’s always a good idea to work in a high resolution format, and shrink to low-resolution as needed.
And if you’re getting your book cover put together by somebody else, and they don’t know any of this that I just went over: find another person right now.