Fujifilm files patent for color filter array with different-sized pixels
Fujifilm has filed a patent for an image sensor that uses a novel layout, with green and clear rectangular pixels which are larger in area than their neighboring blue and red pixels. The idea behind it is apparently to reduce luminance noise at the expense of colour noise, on the grounds that the human eye is less sensitive to the latter.
Fujifilm is no stranger to unusual image sensor designs. Where almost all other cameras use a 'Bayer' pattern, with a regular repeating grid of red-, green- and blue-sensitive pixels, its current X-series cameras almost all use the 'X-Trans CMOS' sensor, which uses a less-regular colour filter array that's designed to reduce image artefacts such as aliasing and colour moiré. It also used the 'EXR-CMOS sensor' in some of its recent compacts, which employs neighboring pairs of same-colored pixels, and can be used to increase the overall dynamic of the image.
|Fujifilm's latest sensor patent||Fujifilm's 'EXR' sensor layout|
|The X-Trans CMOS colour filter array used in Fujifilm's X system cameras||The standard 'Bayer' pattern used in the majority of cameras|
The big advantage of the RGBW filter array used in the latest patent, with one 'clear' pixel per repeat block, is that it's overall more sensitive to light, resulting in less-noisy images in low light conditions. The patent also talks about optimising the area of the readout circuit, which also allows larger, more sensitive pixels. So we'd speculate that this invention is likely aimed at small-sensor compact cameras.
This is only a patent of course, and there's no guarantee the design will ever make its way into an actual product. It's likely to be more difficult to manufacture than a conventional image sensor (and therefore more expensive), and require new image processing methods to construct the final image. But it shows that Fujifilm is continuing to think about alternative sensor designs, while other manufacturers generally seem content with the well-proven Bayer layout.
You can read more about the unusual sensor designs Fujifilm has used recently by following these links:
X-Trans CMOS - Fujifilm X-Pro1 review
EXR-CMOS - Fujifilm X-10 review