Images on your monitor typically have lots of bright light shining through them. That can make your images seem brighter than they really are. When your book or Wall Art is printed those images might look darker than expected.
Luckily, there's an easy way to check and adjust the brightness of your images. You can use an image editing program such as Photoshop, iPhoto, Photos, Preview, or whatever you have available. Look for a feature in those programs called levels or the histogram.
This photo might look OK on screen, especially if your monitor brightness is turned up high...
...but using the Levels tool in Photoshop (below) reveals it's actually pretty dark. There's very little pure white in the image. Those white rabbits would probably look a bit grey in the printed book or Wall Art if printed as-is.
How do we know this? See the graph below that looks like a mountain range? That's the histogram.
The left side of the histogram shows the levels of black. The right side of the histogram shows the levels of white in the photo.
Most images should have a full range, meaning the histogram data should go all the way across from left to right. But here it doesn't go all the way to the right because there's very little true white in the image. (The "white" rabbits are more grey).
You can adjust the black or white levels in the image using the arrows under the histogram. (See screenshot below). This will help bring out the white.
The left arrow adjusts the black levels while the right arrow adjusts the white levels, making whites, well, whiter. (The middle arrow adjusts the midtones, which we'll ignore for now).
To increase the amount of white (and brighten the white areas) slide the right arrow left. There's no exact formula as to how much since every image is different. But aiming for the right edge of the histogram, or just a bit past it, is a good start.
Below, notice where the right arrow is now, and how the rabbit is no longer grey. This white rabbit would now actually look white in print.
For comparison, here's the original photo. See the difference now?
Don't overdo it, though. If you brighten an image too much, things may look washed out on screen and you'll lose detail. Below, I've dragged the right arrow too far the left. The image is now washed out.
With this simple tool and some (minor) adjustments you can get better results in your printed book or Wall Art. If you'd like to learn more, the folks over at Cambridge in Colour have a great article on the levels tool and the histogram.
A few final reminders
- While this article gives some general tips, every image is different and your results may vary.
- The printed image will most always look a bit darker than what you see on your monitor. Most images will benefit from a bit of brightening.
- Ultimately you, the author, are responsible for the content of your book, including the brightness of your images.
- You should always order and review a single, Blurb-printed proof copy before you place a larger order or when working on an important project. That lets you review the book and make revisions before placing the final order. It's also good to order and review a single copy before making your book available for others to buy.
Have questions about your printed book or wall art? Please contact customer support.