Anytime you want to turn a photographic print, slide or flat artwork into a digital image, use a full-color scanner and scanning software. The scanner builds a digital representation of the photograph and creates a corresponding image file. Scanning software can typically store images in PICT (Apple Macintosh) or PCX (PC Paintbrush) formats. Scanners can produce a far higher image resolution than most cameras. The best scanners digitize at least 300 dots per inch resolution with various color depths per pixel (1 to 24 bits per pixel).
Scanners come in two basic varieties: flat-bed scanners and slide scanners. Flat-bed scanners are used to scan printed materials and photographic prints. Slide scanners are used to scan photographic slides. Use a flat-bed scanner if the bulk of your images are flat art or prints. If most of your images are slides, use a slide scanner for quality reproductions.
Many different types of scanner hardware and software are available. If possible, use a scanner that can capture at 24 bits per pixel and at least 300 dots per inch resolution. You'll probably want to edit and archive your scanned images in the original 24 bit format, and then reduce the images to either 8-bit or 4-bit for the actual application. This lets you work with the highest quality image until satisfied it's ready for conversion to the lower resolution.