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<title>CCD camera as a tool for color measurement</title>

1992; SPIE; Volume: 1670; Linguagem: Inglês

10.1117/12.59718

1996-756X

Alex M. Mumzhiu, Christopher D. Bunting,

CCD and CMOS Imaging Sensors

The use of video cameras based on charge-coupled devices (CCD's) for color measurement is a new and growing field which does not fit into any established category of image processing. Just as silicon photodiodes replaced photomultiplier tubes in colorimeters twenty years ago, the CCD array is beginning to replace the silicon diode today. A good colorimeter has a measurement repeatability of the order of 1 part in 10,000, or 0.01 in XYZ or L*a*b*. By contrast, most video frame grabbers are limited to a resolution of 1 part in 256. However, because a color camera can produce in excess of 23 million 8-bit numbers per second, appropriate image processing may be used to improve repeatability and reproducibility dramatically. In this paper, the CCD camera is evaluated from the standpoint of conventional colorimetry. The following points are addressed: requirements of a camera to be used for color measurement; possible physical configurations; sources of noise and repeatability of color measurements; image processing algorithms for colorimetry; RGB-to- XYZ transformation; and requirements for an image processor to be used with a camera-based colorimeter.© (1992) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.