Television – Camera – system and detail – With single image scanning device supplying plural color...
Reexamination Certificate
1997-07-03
2002-04-02
Garber, Wendy R. (Department: 2612)
Television
Camera, system and detail
With single image scanning device supplying plural color...
C348S272000
Reexamination Certificate
active
06366319
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates generally to systems for digital color imaging, and, more particularly, relates to apparatus and methods for providing efficient color processing capability for digital video cameras based on focal plane arrays (FPA). The invention can be used in digital camera systems that are designed to replace conventional silver halide film cameras.
Many high speed motion events are filmed with high speed 16 mm film cameras for motion analysis and diagnostics. Typical frame rates for these cameras range from 500 to 1000 frames per second, and the shutter exposure times are usually less than 500 microseconds. Typical high speed events include airborne weapons separation testing, missile tracking, automotive and aerospace crash testing, manufacturing operations analysis, and others.
Silver halide film, however, requires time-consuming wet chemical processing and handling. Consequently, considerable time elapses before the image results are available for analysis. In addition, film processing requires the use of chemicals requiring storage and disposal. This chemically-intensive process adds to the overall cost of film-based systems.
Further, the film must be optically scanned with a film scanner to convert the image sequence to digital form for computer-aided motion analysis. This extra step can be unacceptably time-consuming.
High speed digital video camera systems have been developed to replace conventional silver halide film cameras. These cameras produce images in digital form that can be stored on digital media (e.g. hard disk, magnetic tape, compact disk, etc.) and analyzed on a computer. These systems provide immediate access to image data, thereby circumventing time-consuming film processing steps.
Conventional high speed digital camera systems are based on FPAs, such as charge-coupled devices (CCDs), which sense broadband visible radiation in the 400-730 nanometer wavelength range. Although monochrome performance can be satisfactory for certain applications, color capability is required for several reasons.
For example, although monochrome digital cameras are suitable for high speed motion analysis of targets that exhibit significant luminance contrast, they cannot distinguish different color objects having similar luminance characteristics.
Color sensing capability can also provide the contrast necessary to distinguish key features in an image, even under low illumination conditions. A color camera thus provides important target tracking and identification capabilities.
For example, identification of different components or fragments can be difficult when using monochrome cameras for impact testing or weapon release testing. By color coding the object(s) under test or using existing color differences, color cameras can be used to readily identify the source of fragments or components during the course of the test.
Further, qualitative evaluation of monochrome video sequences by human observers can be difficult because natural color cues are absent. Routine subjective evaluation of images from color cameras can be performed more efficiently because color images provide human observers with a more realistic reproduction of the test scene. Color cameras also enable interpretation of physical phenomena, such as plasma plume temperatures, during weapons deployment.
Accordingly, many tests and applications which can be undertaken with the use of full color images may be difficult or impossible with black and white images.
Nearly all digital color FPA cameras are based on the principle of color pre-filtering. Since FPAs sense radiation throughout the visible spectrum (400-700 nm), optical color filters must be placed in front of the FPA to sense color. There are several methods for accomplishing this: multiple FPA systems, color filter wheels, and color filter array (CFA) single-chip FPAs.
Multiple FPA configurations have been developed for high-end color FPA cameras. Although these cameras produce images with minimal artifacts and low noise, they are costly and bulky compared to cameras based on a single FPA. In addition, multiple FPA cameras generate as much as three times the amount of data produced by a monochrome camera, thus placing excessive data handling demands on the image storage hardware.
Certain single-chip FPA color cameras utilize a rotating color filter wheel. These cameras cannot be shuttered at high frame rates, due to FPA readout and filter wheel rotation rate limitations. Consequently, this method is substantially limited to still frame applications, and is not suitable for high speed camera applications.
A number of conventional FPA video camera systems provide color sensitivity by means of color filter arrays (CFAS) placed in front of, or deposited directly on, a single-chip FPA. “Additive” CFA/FPA combinations, utilizing red, green, and blue (RGB) filter “mosaics,” have been in common use since the mid-1970's. These mosaics attempt to match the wavelength-dependent sensitivity of the human eye by including a larger percentage of green pixels than red and blue pixels.
By way of example, reference is made to the following U.S. and European Patent Office patents and other publications, the teachings of which are incorporated herein by reference:
4,282,547
Morishita
4,403,247
Sone et al.
4,646,139
Takei et al.
4,714,955
Nishimura et al.
4,716,455
Ozawa et al.
4,939,573
Teranishi et al.
5,008,739
D'Luna et al.
5,373,322
Laroche et al.
5,382,976
Hibbard
5,521,640
Prater
4,479,143
Watanabe et al
4,710,804
Ide
5,172,227
Tsai et al
3,971,065
Bayer
4,591,900
Heeb et al
4,125,856
Netravali et al
4,775,885
Sato et al
4,477,832
Takemura
4,513,312
Takemura
5,136,370
Chi
4,450,475
Ishikawa et al.
4,794,448
Takizawa
5,276,508
Boisvert et al.
5,235,412
Boisvert et al.
5,414,465
Kodama et al.
4,774,565
Freeman
4,642,678
Cok
4,176,373
Dillon et al.
5,032,910
Cok
5,065,229
Tsai et al.
5,053,861
Tsai et al.
5,398,086
Martinez-Uriegas et al.
5,541,653
Peters et al.
EP 732859
EP 211320
“Enabling Technologies for a Family of Digital Cameras”, Parulski and Jameson, SPIE Vol. 2654, pp. 156-163, 1996;
“Single-Chip Color Camera Using a Frame-Transfer CCD”, Aschwanden, Gale, Kieffer, Knop;
IEEE Transactions on Electron Devices
, Vol. ED-32, No. 8, August 1985, pp. 1396-1491;
“A New Class of Mosaic Color Encoding Patterns for Single-Chip Cameras”; Knop and Morf;
IEEE Transactions on Electron Devices
, Vol. ED-32, No. 8, August 1985, p. 1390-1395;
“Color Filters and Processing Alternatives for One-Chip Cameras”; Parulski;
IEEE Transactions on Electron Devices
, Vol. ED-32, No. 8, August 1985, pp. 1381-1389;
“Color Image Compression for Single-Chip Cameras”; Tsai;
IEEE Transactions on Electron Devices
, Vol. 38, No. 5, May 1991, pp. 1226-1232;
“Color Imaging System Using a Single CCD Array”; Dillon, Lewis, Kaspar;
IEEE Transactions on Electron Devices
, Vol. ED-25, No. 2, February 1978, pp. 102-107;
Hunt, R. W. G.,
Measuring Colour
, Ellis Horwood Limited, 1995.
In systems using conventional, additive CFA/FPA devices, before the user can view the captured images in color, the image data must be “decoded.” In the decoding process, mathematical interpolations are executed to recreate three full-resolution color “planes” (the red, green and blue (RGB) planes common to conventional, additive CFA systems) from the original image. A number of color decoding schemes have been developed to recreate the full RGB color planes from an RGB CFA plane. These processing methods are employed in some still-frame point-and-shoot color CCD cameras and 35 millimeter digital camera back products.
However, conventional “additive” CFA imaging systems using RGB sampling and processing suffer from significantly reduced light sensitivity, compared to monochrome FPA imaging systems. The sensitivity of a conventional RGB single-chip color FPA camera is significantly less than its monochrome counterpart due to absorption of light in the red, green and blue elements of the CFA. By way of example, the transmission efficiencies of conventional red, green
Cobrin & Gittes
Garber Wendy R.
Moe Aung S.
Photronics Corp.
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