A Novel Color Filter Array Design

Summary Background

In digital imaging applications, data are typically obtained via a spatial subsampling procedure implemented as a color filter array (CFA). CFA assigns a separate primary color to each pixel by placing a filter of that color over the pixel. The most well known CFA is the Bayer pattern which uses a checkerboard pattern with alternating rows of filters. The Bayer filter has twice as many green pixels as red or blue and takes advantage of the human eye’s tendency to see green luminance as the strongest influence in defining image quality.

Shortcomings of the Bayer Pattern Scheme

Despite its widespread use, the Bayer pattern imposes inherent limitations upon the design of interpolation and denoising methods. In particular, the rectangular subsampling lattice associated with Bayer-patterned data induces spectral copies of the difference signals centered about the set of frequencies. Hence, by reducing allowable bandwidth, the Bayer spectral periodization “penalizes” the very horizontal and vertical features which are most likely to appear in typical “real world” images.


The invention is a new alternative to the Bayer pattern for spatial subsampling in color imaging applications. It arises naturally from a new design paradigm for spatio-spectral sampling. The proposed scheme offers the potential to significantly reduce hardware complexity in a wide variety of applications, while at the same time improving output color image quality.

Patent Status: Pending.

Applications CMOS or CCD image sensor for digital still cameras and digital video cameras; color image processing. For Further Information Please Contact the Director of Business Development Alan Gordon Email: alan_gordon@harvard.edu Telephone: (617) 384-5000

Inventor(s): Wolfe, Patrick J.

Type of Offer: Licensing

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