Inventors:
David L. Alston - Holland PA
Walter Borys - Robbinsville NJ
Mark Jarvis - Burlington NJ
Assignee:
Color and Appearance Technology, Inc. - Princeton NJ
International Classification:
G06K 900
Abstract:
A color and appearance measurement apparatus combines a computer controlled color video camera, controlled illumination conditions, frame grabber to digitize the video signal, and image processing methods to perform non-contact calorimetric measurements of complex patterns of color. Video images of samples placed into the field of view of the camera are digitized and converted from the color camera's red, green, and blue (RGB) color space to the internationally recognized and standardized CIE XYZ color space. A calibration process to set the dynamic range of the camera for the given illumination, correct for spatial non-uniformities in the lighting and responsivity of the detector arrays, correct for temporal variations in the lighting intensity, and determine the necessary coefficients to transform the RGB values to CIE XYZ tristimulus values ensures the measurements are highly repeatable and that measured color and appearance differences are in agreement with visual observations. Visual appearance attributes of the samples such as color, texture, and gloss are measured and evaluated. These measurements provide quantifiable metrics, to which various color and appearance attributes of other samples can be compared, for quality control inspection of complex colored samples that cannot be measured using conventional color measuring instruments.
