Imagine viewing concert footage where the foreground vocalist is in the same sharp focus as the background musicians. With the simultaneous, real-time, near and far field focus capabilities offered by the Omni-focus video camera developed by Professor Keigo Iizuka, such a thing may not be too far off. Using a new distance mapping principle, an array of video cameras and some clever software the technique brings objects at varying distances into high resolution sharp focus.

Professor Keigo Iizuka of The Edward S. Rogers Sr. Department of Electrical and Computer Engineering at the University of Toronto developed the novel distance mapping principle after realizing that "the intensity of a point source decays with the inverse square of the distance of propagation." Taking this further, Professor Iizuka found that the "variation with distance has proven to be large enough to provide depth mapping with high resolution. What's more, by using two point sources at different locations, the distance of the object can be determined without the influence of its surface texture."

This, in turn, led to the creation of the Divergence Ratio Axi-Vision Camera or DivCam, which uses the decay rate of illuminating light as a yardstick for three dimensional distance mapping of one or more target objects. The DivCam has an illuminating infrared LED in front of the camera and one behind. The camera snaps one shot using each LED, which are identical except for their optical density. Using a pixel by pixel approach, the difference between the two images is used to calculate distance.

Multiple focus points

Iizuka then integrated the DivCam with an array of video cameras each set to focus at different distances. Each pixel from the scene was mapped using information from the DivCam and then merged with the video camera output with software developed by Dr. David Wilkes of Wilkes Associates. The result was a final "omni-focused" single-video image. Using a two camera array, a distant and near object are brought into simultaneous focus, with the final output being so sharp that the near object fingerprints can be seen.

Dr. Wilkes said of the development: "The Omni-focus Video Camera's unique ability to achieve simultaneous focus of all of the objects in a scene, near or far, multiple or single, without the usual physical movement of the camera's optics, represents a true advancement that is further distinguished in terms of high-resolution, distance mapping, real-time operation, simplicity, compactness, lightweight portability and a projected low manufacturing cost."

Still in the research phase, further refinements could see the technology making its way into broadcast television removing current limitations which restrict focus to either the foreground or background at any one time. Professor Iizuka also sees potential medical applications: "I'd like to apply the principle of the Omni-focus Video Camera to the design of a laparoscope. It would help doctors at the operating table, if they can see the entire view without touching optics of the laparoscope, especially if dealing with a large lesion."

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