Do you have printed images, antique photos, newspaper clippings, artwork, handwritten or typed letters, or other printed documents you'd like to place in your book?
If so, you can take digital photos of those objects or you can scan them. Scans will often provide the best results, especially when you use the correct settings.
Tips for scanning
Blurb can't scan your old images for you but you can pay someone to do it (google photo scanning service) or you can do it yourself.
You can find lots of valuable tips on scanning images on www.scantips.com. (This is an external site with no association with Blurb--we just find it a useful resource). You'll find best practices for scanning and an overview of digital images in general. You'll also find some very complex explanations for those who are really into such details.
Here are a few of the more relevant pages from the scantips.com site:
Never used a scanner before?
Image file formats
The first fundamental concepts of digital images
Scan as TIFF and export to PNG
JPG/JPEG, PNG, and TIFF files are all different types of image file formats, each with their own advantages. When it comes to scanned content, the format you choose can make a big difference.
If your scanner has the option it’s best to save scans as TIFF files. TIFFs are a “lossless” format and will preserve the greatest amount of detail and data. That matters a lot when scanning things like old letters, photos or newspaper articles, as well as illustrations, graphs, and line art.
If your scanner doesn’t have the option to save as TIFF files and you have to choose between JPG or PNG then always select PNG.
PNGs and TIFFs both use lossless compression while JPGs are a “lossy” format. JPGs are fine for most photos straight from a camera. But they’re not ideal when trying to capture the fine details found in scanned content. Avoid saving or exporting scanned content as JPGs.
TIFF files aren't supported in BookWright, BookSmart, or Blurb’s iOS app but that's OK. When it’s time to place the image into your book, simply open the TIFF file and export/save it as a PNG. You can then use the PNG in your book (and your original TIFF will be preserved).
In short: scan as TIFF, then export to PNG before placing the image in your book.
Scan quality
If you're seeing grain or a thatched/blocky pattern in your scanned images, try the tips here:
http://www.scantips.com/basics06.html
Finally, as with any image you use in your book (a scan or otherwise), if you're unsure about the quality give it the 200% test.
Of course, the ultimate test is the printed Blurb book, so it's always a good idea to order and review a single copy from Blurb before placing a larger order.