CHROMAPLEX
Chromaplex Overview
Chromaplex is a new technique for the processing of digital color images. Based on SRI's research in the multiplexing process of human color vision, Chromaplex represents a full-color image with a single plane of pixel values rather than three overlaping planes. Moreover, this single plane is compatible with monochrome compression schemes based on spatial variation.
Chromaplex Fundamentals
Human vision is trichromatic, which means that to match the appearance of any patch of light, the human eye requires a weighted mixture of at least three color primaries. The physiological evidence related to this fact is that the human retina has three different types of photoreceptors (L, M, and S cones) for daylight performance. The need for three corresponding image planes (R, G, and B) in CRT color imagery arises from this human trichromacy. Accordingly, the standard for digital color images is a set of three arrays of numbers, which represent overlapping RGB values at each point (pixel) of the image.
This latter aspect, however, does not correspond to the retinal organization where the three types of cones are not arranged in three separate tiers, but interspersed in a single tier. Signals from cone cells are not independently processed but interact locally. Moreover, neural processes of chromatic and achromatic changes in the image are not independent. Instead, for each point in the retina, the chromatic and achromatic changes of the light falling upon it are processed in a multiplexed local fashion by neurons associated with that point. Later processes in the visual cortex separate the chromatic from the achromatic information.
Chromaplex is based on two essential characteristics of the visual multiplexing process: (1) a single tier or layer comprising three types of color elements, and (2) decoding (demultiplexing) of chromatic and achromatic information based on interactions within small local regions. In broad terms, this technique reduces, with minimal computation, three RGB planes into a single plane, which can be further compressed by a single-plane process like that of JPEG. After single-plane decompression (JPEG or otherwise), the decompressed plane is decoded into three RGB planes that render a high quality color image comparable to the original.
Applications
The advantages of Chromaplex are readily applicable in the following areas:
- Simplification of processing and compression of digital color images
- Economic conversion of monochrome image capturing systems to full color
- Increase by 4 times the spatial resolution of high-end image capturing systems currently designed for 3-CCD color capture
- Extension of these applications to digital video systems where additional advantages are available
Licensing
SRI has patented the Chromaplex process (US Patent No. 5,398,066) and (US Patent No. 5,541,653) and is currently forming partnerships to commercialize applications using Chromaplex technology.
Any questions? Please call:
Dr. Eugene Martinez-Uriegas
(415) 859-3010 ||| uriegas@sri.com
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