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.

Abstract: A color measuring system uses fuzzy logic to establish acceptable pass/fail tolerances for production or inventory samples. The tolerances define a super ellipsoid which has six individual tolerance coordinates. Initially, the tolerances are defined by the high/low values of the pass samples in a training set which have been chosen to represent a population of visually rated pass and fail samples. A classifier template uses the super ellipsoid tolerances and ranks every sample in the training set. Any pass/fail ranking that differs from the visual rank is considered an error. All of the error distances are summed and all samples are passed through the fuzzy logic contained in an induction module to determine the changes needed in the super ellipsoid tolerances to minimize the error distance. The new tolerances are then passed to the classifier template for a new ranking of the training samples. The process is repeated until a minimum error distance is achieved.

Abstract: A hand-held combined spectrophotometer and gloss meter quickly and effectively measures the appearance of a color sample. Light generated by a krypton-filled tungsten bulb shines on the sample and is reflected at 45.degree. into twenty-one photodiodes spaced at staggered intervals around the sample stage. A diffuser in the light path reflects a portion of the light back onto a pair of red and blue sensitive reference photodiodes. The output of the red and blue reference diodes compensates for changes in the output of the bulb. An LED produces light which shines on the color sample at an angle of 30.degree.. The reflected light is received by a large-area photodetector which determines the gloss of the sample. A viewing port permits the user to view the sample prior to measurement. When the viewing port door is opened, it automatically actuates the light and illuminates the sample for viewing. The viewing port door is automatically closed by a return spring.