Optical color analysis process
First Claim
1. A process for analyzing colors in a viewing region in an object comprising illuminating the viewing region in predetermined light, scanning the viewing region with a video camera so as to produce an electronic video output for the color values at each pixel location representative of the viewing region, converting the video output into digital data for individual components of the colors, reporting and storing the digitized values in a computer memory, analyzing the digital component values to determine the means value of the component values and the extent of variation of component values from the mean value;
- and selecting a predetermined variation from the mean value as a tolerance limit for comparing other colors, the tolerance limit being determined as a function of the deviation of the component values from the mean.
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Abstract
A process for color analysis and comparison among reference and test samples for use in quality control applications or the like comprises illuminating each sample under predetermined lighting conditions, scanning the sample with a color video camera, digitalizing the video signal output to produce a digitized signal representative of the components of the color values, preferably the red-green-blue and brightness values ("RGBW"), for each pixel representative of the viewed signal, and reporting and storing the digitized data for subsequent analysis, comparison, display and printout. For comparison purposes, the pixel color values for the samples are analyzed and compared statistically to determine if the reference and test sample match. In one test, the mean of the pixel color value for each sample is ascertained and the test sample is analyzed to determine if its mean is within a tolerance limit for the reference sample expressed in terms of standard deviation values. Various statistical tests provide useful information.
120 Citations
20 Claims
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1. A process for analyzing colors in a viewing region in an object comprising illuminating the viewing region in predetermined light, scanning the viewing region with a video camera so as to produce an electronic video output for the color values at each pixel location representative of the viewing region, converting the video output into digital data for individual components of the colors, reporting and storing the digitized values in a computer memory, analyzing the digital component values to determine the means value of the component values and the extent of variation of component values from the mean value;
- and selecting a predetermined variation from the mean value as a tolerance limit for comparing other colors, the tolerance limit being determined as a function of the deviation of the component values from the mean.
- 2. A process for analyzing colors in a viewing region in an object comprising illuminating the viewing region in predetermined light, scanning the viewing region with a video camera so as to produce a electronic vide output for the color values at each pixel location representative of the viewing region, converting the video output into digital data for individual red, green and blue ("RGB") components of the colors, reporting and storing the digitized values in a computer memory for subsequent analysis of the pattern of variation of the color values among the pixel locations, for comparison with other colors and for display, the object being viewed on a background in the viewing area and the background alone being scanned with the video camera before viewing the object, the color of the video output for the background being converted to RGB digitized values as background values and stored in the same manner as the output for the object, the background values being compared with the viewing area for the object and cancelled from the digital data for the viewing area containing the object, the resulting values reported being limited to the object and having eliminated therefrom any background values.
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4. A process for comparing colors of different objects comprising analyzing colors in a viewing region in one object by illuminating the viewing region in predetermined light, scanning the viewing region with a video camera so as to produce an electronic video output for the color values at each pixel location representative of the viewing region, converting the video output into digital data for individual components of the colors, reporting and storing the digitized values in a computer memory;
- repeating the foregoing process for another object; and
comparing the digitized color component values of one object with the other object, the color component values for viewing regions on the two objects having been detected and stored separately, the difference between the mean color component values being determined so as to ascertain the degree of difference between the two colors for each of the color components, the difference indicating the amount of change necessary for each component in order to make the overall colors of the objects the same. - View Dependent Claims (5, 6, 7, 8, 9)
- repeating the foregoing process for another object; and
- 10. A process for analyzing the color of a viewing region in a reference object comprising sampling individual color values at each of a large number of discrete locations on the viewing region, separating the color values into one or more component values and converting the values into numeric values, statistically comparing the numeric values of the components for the discreet locations on the viewing region so as to provide a statistical analysis of the variation in the color value in the viewing region, the analysis providing information about the nature and extent of color variation over the viewing region and not just a value reflecting an average color, the color values being sampled with a video camera, the discrete locations being the areas covered by individual pixels of the camera, the video signal being converted into a digitized electronic signal representing the numeric value of each color component for the pixel locations, the digitized values being compared by statistical analysis to determine the extent of variation of color values in the viewing area, the digitized color values being stored electronically for subsequent reference, the digitized color values being analyzed in accordance with statistical principles of standard deviations.
- 12. A process for comparing colors in different viewing regions comprising analyzing the color of a viewing region in a reference object comprising sampling individual color values at each of a large number of discrete locations on the viewing region, separating the color values into one or more component values and converting the values into numeric values, statistically comparing the numeric values of the components for the discreet locations on the viewing region so as to provide a statistical analysis of the variation in the color value in the viewing region, the analysis providing information about the nature and extent of color variation over the view region and not just a value reflecting an average color, the color values being sampled with a video camera, the discrete locations being the areas covered by individual pixels of the camera, the video signal being converted into a digitized electronic signal representing the numeric value of each color component for the pixel locations, the digitized values being compared by statistical analysis to determine the extent of variation of color values in the viewing area, the digitized color values being stored electronically for subsequent reference, the color in the viewing region for the reference object being compared with a color value for a second viewing region for a second object, with the color in the second viewing region being sampled and digitized in the same manner as the color for the reference object, the second viewing region color being compared with the reference object viewing region color by a statistical comparison of the respective color values.
Specification