As an arrangement of color filters mounted in a solid-state imaging device, various arrangements have been proposed and used. For example, an imaging apparatus disclosed in Patent Document 1 below uses a color filter arrangement which is called the Bayer arrangement. In the Bayer arrangement, color filters of any one of the three primary colors of R (red), G (green), and B (blue) are arranged in a mosaic pattern in respective pixels on the basis of a predetermined rule. In a red pixel in which a red filter is mounted, for example, green and blue signals therefore cannot be detected. Consequently, an interpolation calculation is performed on signals of pixels which are in the periphery of the red pixel, and in which green and blue filters are respectively mounted, thereby obtaining the green and blue signals at the position of the red pixel.
In an imaging device disclosed in Patent Document 2 below, each two pixels which are adjacent to each other in an oblique direction are paired, and color filters of one of the three primary colors of RGB are arranged in a mosaic pattern in the unit of paired pixels in accordance with a predetermined rule. For example, a G1 color filter and a G2 color filter are mounted on a pair of pixels on each of which a green filter is mounted, respectively.
The relationship between G1 and G2 is set so that the color of G is attained by, for example, adding them to each other. The color filter of G is produced so that the wavelength of 540 nm is set as the center wavelength, and bell-shaped spectral characteristics having a width of about 100 nm in each of the back and front sides are obtained. By contrast, for example, G1 and G2 are separated in two filters so that the G1 filter detects a color having a wavelength of 440 nm to 540 nm, and the G2 filter detects a wavelength of 540 nm to 640 nm. With respect to the colors of R and B, similarly, R1 and R2 filters are mounted on paired pixels, and B1 and B2 filters are mounted on paired pixels.
When, as described above, colors to be separated by color filters are separated more finely than the case of the three colors of R, G, and B, the color reproducibility of an object image can be improved. However, a captured image taken out from pixels on which the R1, G1, and B1 color filters are mounted, and that taken out from pixels on which the R2, G2, and B2 color filters are mounted are different in color tone from each other. When the images are singly viewed, the images are color images having an unnatural color tone. Therefore, adequate image combination processing must be performed so that an object image having high color reproducibility is obtained by image processing.
In an imaging apparatus disclosed in Patent Document 3 below, each pixel is divided into a small-area portion and a large-area portion. In each of pixels on which, for example, a green (G) filter is mounted, moreover, the thickness of a filter mounted on the small-area portion is made larger than that on the large-area portion, or that of an n-region constituting a photodiode is reduced.
As a result, the small-area portion cannot substantially detect incident light of a certain wavelength region, and the large-area portion can detect light of the wavelength region. By using this, the imaging apparatus detects whether light of the wavelength region exists or not, and determines the kind of the light source.