Method and system for measuring color difference
First Claim
1. A method for automatically measuring color difference between color distribution of an object and a reference color image of the object in a machine vision system having a memory, the method comprising the steps of:
- storing a template in the memory of the machine vision system, the template representing the reference color image of the object and having a first set of pixels;
generating a sample color image of the object having the color distribution and having a second set of pixels; and
processing the template and the sample color image together on a pixel-by-pixel basis to obtain a total color distance accumulated over matched pixels in the first and second sets of pixels in an area of the object, the total color distance representing a statistically meaningful color measurement between the color distribution and the reference color image of the object in a color system.
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Abstract
A method and system are provided for automatically and quantitatively measuring color difference between a color distribution of an object and a reference color image using "color distance" in a color system. A template representing the reference color image is stored in a memory of a machine vision system. The machine vision system generates a sample color image of the object and processes the template together with the sample color image to obtain a total color distance. Color distance may be measured either in a Euclidean or "City Block" fashion. Preferably, a look-up table stores the template. The color system may be either intensity dependent or independent. The total color distance can either be presented or displayed to an operator of the machine vision system or else can be used in an automatic feedback loop of a controller of a machine or process.
168 Citations
40 Claims
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1. A method for automatically measuring color difference between color distribution of an object and a reference color image of the object in a machine vision system having a memory, the method comprising the steps of:
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storing a template in the memory of the machine vision system, the template representing the reference color image of the object and having a first set of pixels; generating a sample color image of the object having the color distribution and having a second set of pixels; and processing the template and the sample color image together on a pixel-by-pixel basis to obtain a total color distance accumulated over matched pixels in the first and second sets of pixels in an area of the object, the total color distance representing a statistically meaningful color measurement between the color distribution and the reference color image of the object in a color system. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20)
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21. A color measuring system for automatically measuring color difference between a color distribution of an object and a reference color image of the object in a machine vision system, the system comprising:
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a memory for storing a template, the template representing the reference color image of the object and having a first set of pixels; means for generating a sample color image of the object having the color distribution and having a second set of pixels; and a processor for processing the template and the sample color image together on a pixel-by-pixel basis to obtain a total color distance accumulated over matched pixels in the first and second sets of pixels in an area of the object, the total color distance representing a statistically meaningful color measurement between the color distribution and the reference color image of the object in a color system. - View Dependent Claims (22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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Specification