Single-Sensor Camera Image Processing

In recent years a massive research and development effort has been witnessed in color imaging technologies in both the industry and the ordinary life. Color is commonly used in television, computer displays, cinema motion pictures, print, and photographs. In all these application areas the perception of color is paramount for the correct understanding and dissemination of the visual information. Recent technological advances have reduced the complexity and the cost of color devices, such as monitors, printers, scanners, and copiers, thus allowing their use in the office and home environment. However, it is the extreme and still increasing popularity of the consumer, single-sensor digital cameras which boosts today the research activities in the field of digital color image acquisition, processing, and storage. Single-sensor camera image processing methods are becoming increasingly important due to the development and proliferation of emerging digital camera-based applications and commercial devices, such as imaging enabled mobile phones and personal digital assistants, sensor networks, surveillance, and automotive apparatus. This chapter focuses on single-sensor camera image processing techniques with particular emphasis on image interpolation based solutions. The chapter surveys in a systematic and comprehensive manner demosaicking, demosaicked image postprocessing and camera image zooming solutions which utilize data-adaptive and spectral modelling principles to produce camera images with an enhanced visual quality. The existence of realistic and efficient design procedures and the variety of processing solutions developed through the presented data-adaptive, spectral model-based processing framework make this family of processing methodologies an indispensable tool for single-sensor imaging. 435 The chapter begins with Section 16.2 which briefly discusses the digital camera solutions, emphasizing cost-effective hardware architecture for a consumer-grade camera equipped with a color filter array placed on the top of a single image sensor. The most common color filter array layouts are also introduced and commented upon. The next part of the chapter, Section 16.3, describes the work-flow in the single-sensor cameras. Particular emphasis is placed on the essential camera image processing of the sensor data. The second part of this section presents various image processing paradigms which are taxonomized according to their ability to follow the structural and the spectral characteristics of the acquired image. This section also introduces the so-called generalized camera image processing solution and lists the spatial, structural, and spectral constraints imposed on such a solution in practical applications. This part of the chapter also includes Section 16.4 which focuses on edge-sensing processing mechanism and Section 16.5 …