Canon was yesterday granted US patent 6,388,709 (filed in 1996) which is titled "Image sensing apparatus with optical modulation elements having transmission characteristics controllable by pixel". This patent goes on to describe an image sensor which can control the colour of the filter in front of each pixel. From looking through the diagrams it appears the idea is to capture two images, each with a shifted RRGGBGG pattern and then combine these two images to produce a full colour image output. This design also allows the control of the amount of light to each pixel, extending dynamic range. - Our thanks to Wilfried Bittner for spotting this.

US Patent 6,388,709

"An image sensing apparatus having a solid-state image sensing device is provided with an optical modulation element, made of electrochromic element for R, G, and B layers, whose spectral transmission characteristics can be independently controlled. By controlling the spectral transmission characteristics of each layer of the optical modulation element, visible light in R, G and B wavelength ranges is controlled so as to incident on a photoelectric converter of the solid-state image sensing device at different times. "

Click here to visit the US Patents Office website

Then click on 'Quick Search' and enter the patent number 6388709

Thanks to Wilfried Bittner for spotting this.

Phil: I'm struggling to see how this would work properly, if you took a shot at 1/20 sec the camera would need to capture two images at 1/40 sec intervals to build up the full R G B image. If anyone else would like to add to this news article please don't hesitate to email me.

UPDATE: Maybe it would be possible to flicker the colour of the filter in front of the pixel at a very high frequency and thus just take one shot.