1. Field of the Invention
The present invention relates to an apparatus and a system for processing an image signal output from a solid state imaging device such as a CCD or a CMOS.
2. Description of the Background Art
A typical digital camera is equipped with a solid state imaging device (which will hereinafter be abbreviated to an “imaging device”) such as a CCD or a CMOS. Conventionally, digital cameras of a type which is equipped with a single imaging device (which will hereinafter be referred to as a “single chip digital camera”), as well as digital cameras of a type which is equipped with three imaging devices designed to provide R (red), G (green) and B (blue), respectively, (which will hereinafter be referred to as a “3-chip digital camera”), have been widely used. In a single chip digital camera, a R, G or B color filter is provided on each pixel of a light receiving part of an imaging device. The color filters are arranged in a well-known Bayer pattern or the like. In the single chip digital camera, the imaging device captures an image to produce an image signal, and pixel interpolation is performed on the produced image signal so that each pixel has plural color components for R, G and B. However, the pixel interpolation causes problems of reduction in resolution, generation of false color and the like, as is known.
As for a 3-chip digital camera, there is a need of processing image signals output in parallel from three imaging devices. This complicates circuit arrangement for image processing, to easily invite increase of manufacturing cost. Additionally, details of image processing performed by a 3-chip digital camera can be found in Japanese Patent Application Laid-Open No. 10-308901, for example.
In the meantime, in recent years, a single full-color imaging device such as “Foveon X3 direct image sensor” in which each pixel is provided with three layers of light receiving parts for R, G and B, respectively, has been developed. In this type of imaging device, an incident light is detected by each of the three layers of light receiving parts for R, G and B. As a result, component signals for three colors of R, G and B are output in parallel from a single chip, and pixel interpolation is unnecessary. As such, the single full-color imaging device is advantageous in that the above-noted problems of reduction in resolution, generation of false color and the like are not likely to occur. Additionally, details of the single full-color imaging device can be retrieved from internet http://www.foveon.com/X3_better.html, for example.
As the foregoing type of imaging device, i.e., a single full-color imaging device, becomes more widely available, a demand for a low-cost and small-scale image processing chip which has low power consumption and can be adapted to a digital camera equipped with a single full-color imaging device, as well as to the conventional single digital camera, increases.