Don’t Forget Stock Illustrations
As with stock photography, the selection and variety of stock illustrations has grown tremendously with the advent of digital delivery. These illustrations, available in both full-color and grayscale (or you can just convert a full-color image to grayscale if necessary), come in many different styles covering a vast selection of themes, concepts, and subject matter. You can alter them to suit your needs, just as you can photographic images.
Like stock photos, you can browse through a CD or through samples online. Look for images to spark ideas for whatever project you’re working on.