Color image acquisition

Abstract

Color images of scenes and objects can be captured on photographic film by conventional cameras, on video tape by video cameras, and on magnetic disk or solid-state memory card by digital cameras. Digital color images can be digitized from film or paper by scanners. In this chapter, we will cover these major color image acquisition devices. Photographic film has the longest history and still offers a convenient, low-cost, high-quality means for capturing color images. For this reason, it is very useful to understand the photographic processes, photographic film and photographic paper, because they are often the sources of many color images that we will encounter. They have some unique properties that influence how film-originated digital color images should be processed by computers. The next in importance is the solid state sensors, of which charge-coupled devices (CCDs) are the most widely used so far, with others (such as complementary metal-oxide–semiconductor (CMOS) sensors) gaining in popularity. Scanners are devices that are used to digitize images from film and paper. They are the main devices for generating high-quality digital color images. Most scanners use CCD sensors, except some high-end graphic arts scanners that use photomultiplier tubes. Digital cameras are becoming more and more competitive with photographic films in terms of image quality and convenience. Most digital cameras today also use CCD sensors. Each of these devices has different characteristics and unique image processing problems. They are discussed separately. General considerations for system design and evaluation Color image acquisition systems are designed under a lot of practical constraints. Many system components are designed and manufactured separately.