ABSTRACT
Consumer-level digital cameras were introduced in mid-1990s; in about a decade, the digital camera market has grown rapidly to exceed film camera sales. Today, there are point-and-shoot cameras with more than 8 million pixels; professional digital single lens reflex (SLR) cameras with more than 12 million pixels are available; resolution, light sensitivity, and dynamic range of the sensors have been improved significantly. Image quality of digital cameras has become comparable to that of film cameras. During an image capture process, a digital camera performs a significant amount of processing to
produce a viewable image. This processing includes auto focus, white balance adjustment, color interpolation, color correction, compression, and more. A very important part of the imaging pipeline is color filter array interpolation or demosaicking. To produce a high-quality color image, there should be at least three color samples at each pixel
location. One approach is to use beam-splitters along the optical path to project the image onto three separate sensors as illustrated in Figure 28.1. Using a color filter in front of each sensor, three full-channel color images are obtained. This is a costly approach as it requires three sensors and these sensors should be aligned precisely. A more convenient approach is to put a color filter array (CFA) in front of the sensor to capture one color component at a pixel and then interpolate the missing two color components. Because of the mosaic pattern of the CFA, this interpolation process is known as demosaicking.
