While our creation tools will warn you if an image's resolution isn't high enough to print well, it's impossible for our tools to identify and warn you about issues like grainy or blurry images, jaggies or compression artifacts.
This is where your own eyes come in.
Use the 200% test
Images may look fine from a distance or when viewed on your camera or phone but a close-up look will reveal any flaws. If you have any doubts about your image, use a photo-viewing program to zoom in to your image to 200% and see how the image looks. (If uploading a PDF to Blurb, you can do the same test with the PDF).
This is a useful check for *any* image and you should definitely do the 200% test on any image you converted from another source, like a PDF or Word document, or any image that was scanned.
How to zoom to 200%
- Using a Mac: zoom in with Preview and follow these instructions.
- Using Windows: try these instructions for zooming in on an image.
- If previewing a PDF we recommend using Acrobat Reader.
- If your image looks sharp and not grainy at 200% then it will probably look ok in print. (See sample images below).
Although the 200% test is useful, your printed Blurb book is the ultimate test. (The 200% test won'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 and review a single, Blurb-printed copy first.
What if images look bad at 200%?
If your original images look grainy, blurry, pixelated, jagged or just plain bad at 200%, they will look that way (or worse) in print. If so, there is no ideal way to fix poor quality originals. Attempting to fix the images (by sharpening them in Photoshop, for example) can only do so much and may make things worse if overdone.
How to avoid grain, blur and pixelation
Avoid a high ISO setting on your camera
When taking photographs make sure your camera's ISO setting isn't too high. (Higher ISO = greater chance of grainy images). By keeping your ISO setting as low as lighting allows, you minimize the risk of grainy images.
There's no magic number and every camera handles ISO a bit differently but the higher the ISO, the more likely you'll encounter digital noise and grain in your images.
Avoid using low resolution images
While low resolution images might look fine on your monitor, depending on how big you stretch them for your 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.
If the low-res warning appears, reduce the size of the image on the page until the warning goes away. (Remember, the low-res warning only checks the size of the image. It can't detect blurriness, grain, pixellation, or too-dark images).
One common cause of blurry images is camera shake. You can avoid that issue by stabilizing your camera with a tripod and using the timer setting on your camera or a remote control shutter release (pressing the button can lead to camera shake).
If shooting with a phone, you become the tripod. Steady yourself against something if possible.
Focus, focus, focus
When taking photos, be sure to focus on your subject. Out-of-focus images will not print well. If you're shooting portraits, the general consensus is to make sure your subject's eyes are in focus over anything else.
Here's a screenshot 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 ("soft") and nothing is 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 other example.
Finally, one last example:
And the same image at 200%...notice how it's still sharp?