Scanning & Images
If you are planning to add photographs or documents to your book, they must first be scanned in order to be converted into a digital file. There are many brands of scanners available on the market. Even the most inexpensive scanner will be able to produce the high-quality image files needed for printing. For best results, photos should be scanned at 300 DPI and saved as a TIFF or JPEG file. If you are planning to print a photograph larger than its original size, we would recommend scanning the photograph at 600 DPI to ensure a high-quality result. Some scanners automatically default to 72 DPI between scans so be careful. Photos scanned and printed at 72 DPI would not be considered acceptable for printing. On the other hand, higher resolution is not necessarily better. A resolution over 300 DPI will increase your file size (sometimes dramatically) and cause your computer to run more slowly. For those who prefer not to scan their own photographs, we offer a complete scanning and page layout service.
Full color images (illustrations, photographs, or scans) require a considerable amount of memory to store as an uncompressed digital file. In order to reduce the file size, an image file can be saved in a variety of formats which allows it to be compressed. Each file format compresses the file differently, resulting in varying degrees of file size. The most common image formats are JPEG and TIFF.
The JPEG file format uses a file compression that permanently removes information from the image it deems as “unneccessary”. This is known as a lossy file format. As a result of information being removed, a JPEG file will require a smaller amount of memory to store the file. The JPEG format is the most popular type of image file.
The TIFF file format uses a compression which results in no loss of information in the image. This is what is referred to as a lossless file format. Instead, information is reorganized and condensed in a more efficient way, resulting in a reduction in the file size. For example, a printed image is made up of fine dots of varying colors. If an image contains 400 dots using the same blue color, an uncompressed file stores the information as “blue dot, blue dot, blue dot”, and so on (400 times in total). When the file is compressed, the information is stored simply as “blue dot x 400”. This is why images containing large areas of the same color will result in yet a smaller file size.
Like everything else in your book, you must own the copyrights to or have permission to use all images. While Internet images can be easily obtained, this does not mean they are free for use. Be sure to check the sources of your images and pay the necessary copyright fees. You may need to contact the artist or relevant institution to obtain permission.