Our bookmaking tools will warn you if your image resolution isn't high enough to print well. However. it's impossible for our tools to identify and warn you about issues like grainy or blurry images, jaggies or compression artifacts. That takes a human eye. The tips below will help you catch such problems.
Remember, Blurb doesn't review your book or its content before it goes to print so make sure things look the way you want them to before you upload and order your book.
Use the 200% test
Images may look fine from a distance or when viewed on a camera or phone but only a close-up view can reveal some flaws. If you have any doubts use a photo-viewing program to zoom in on your image to 200% and see how it looks. (If you’re uploading a PDF to Blurb, you can also zoom in on the PDF).
This is a useful check for any image, but we especially recommend that you perform this 200% test on any images you convert from other sources, like a PDF or Word document or any scanned images.
How to zoom to 200%
On Windows: using the Windows Photo app or Photo Viewer, follow the steps below to zoom in on an image.
- To change the magnification level gradually, in Filmstrip or Single view, use the Zoom slider
- To view a picture at a specific percentage, in Filmstrip or Single view, click the arrow next to the Zoom box on the Standard toolbar, and select the setting you want
If you’re previewing a PDF we recommend using Acrobat Reader.
Although the 200% test is useful for detecting grain and blurry images, your printed Blurb book is the ultimate test. The 200% test can't tell you if your image is too dark to print well, for example. If you plan to order multiple copies, you should always order a single Blurb-printed proof copy first.
What if images look bad at 200%?
If your original images look grainy, blurry, pixelated, or jagged at 200%, they will look that way (or worse) in print. There is no ideal way to fix poor-quality original images. Attempting to fix the images (by sharpening them in Photoshop, for example) can only do so much and may actually make things worse if overdone.
The best solution is to ensure that your original images are as sharp and clear as possible.
How to avoid grainy, blurry, or pixelated images
1. Avoid a high ISO setting on your camera
(This only applies if you're shooting on a DSLR or other camera that lets you manually adjust the ISO setting. If you're shooting with a phone you likely won't have a choice).
When taking photographs make sure your camera's ISO setting is as low as lighting allows. The higher the ISO, the more likely you'll encounter digital noise and grain in your images. Anything 800 or over is generally considered high though every camera handles ISO a bit differently.
2. Avoid using low resolution images
While low resolution images might look fine on your monitor, depending on how large you make them in the printed book they may not print well. Our book-making programs will alert you when the image you're trying to use has a low resolution relative to its size in the image container. If the low-res warning appears, reduce the size of the image until the warning goes away.
Remember, the low-res warning only checks the size of the image relative to the image container. It can't detect blurriness, grain or pixelation that's part of the original image and it can't tell if your images is too dark to print well.
3. Steady the camera
One common cause of blurry images is camera shake. You can avoid that issue by stabilizing your camera with a tripod. Additionally, using the timer setting on your camera or a remote-control shutter release can help to eliminate camera shake.
If you’re shooting with a phone, you become the tripod! Steady yourself against a wall or another surface if possible.
4. Focus, focus, focus
When taking photos, be sure to focus on your subject. Out-of-focus images won’t print well. If you're shooting portraits, the general consensus is to make sure your subject's eyes are in focus.
Here's part of an image viewed at 100%. It doesn't look so bad at first glance...
...but here's the same image zoomed to 200%. Notice how it's actually blurry and nothing's really in focus. It will look just as blurry in print.
Here's another (and sharper) image at 100%.
Here's the same image zoomed in on the hat. Notice it's still relatively sharp, with sharp lines and no strong grain, unlike the previous example.