Colorimetry system for display testing

Abstract

A method for two-dimensional, spatially resolved measurement of tristimulus values of light emitted from a plurality of positions on a sample. In various embodiments, an improved method and system is provided for spatially resolved chromaticity and luminance measurement in a standardized color space for display testing. The method may include directing a first portion of the light to an RGB camera which produces a two-dimensional map of RGB color values; transforming the RGB color values into first tristimulus values to produce a map of tristimulus values; directing a second portion of the light to a colorimeter which produces second tristimulus values; deriving a tristimulus correction by comparing the second tristimulus values with at least a subset of the first tristimulus values; and applying the tristimulus correction to the first tristimulus values to produce a corrected map of tristimulus values. In many embodiments, the imaging colorimeter system is capable of two-dimensional, spatially resolved measurement of tristimulus values of light emitted from a plurality of positions on a sample.

1 . A method for two-dimensional, spatially resolved measurement of tristimulus values of light emitted from a plurality of positions on a sample, comprising the steps of:
 directing a first portion of the light to an RGB camera which produces a two-dimensional map of RGB color values;   transforming the RGB color values into first tristimulus values to produce a map of tristimulus values;   directing a second portion of the light to a colorimeter which produces second tristimulus values;   deriving a tristimulus correction by comparing the second tristimulus values with at least a subset of the first tristimulus values; and   applying the tristimulus correction to the first tristimulus values to is produce a corrected map of tristimulus values.   
     
     
         2 . The method of  claim 1 , wherein the second portion of the light is emitted from a number of positions within a spot on the sample, wherein the colorimeter produces the second tristimulus values without spatial resolution. 
     
     
         3 . The method of  claim 2 , wherein the positions within the spot at least partly overlap with the positions on the sample from which the first portion of the light is emitted. 
     
     
         4 . The method of  claim 1 , wherein the colorimeter is a photoelectric colorimeter comprising a set of at least three color filters and one or more photo sensors. 
     
     
         5 . The method of  claim 1 , wherein the colorimeter is a spectral photometer. 
     
     
         6 . The method of  claim 1 , wherein the transformation for transforming the RGB color values into the first tristimulus values is derived in a prior training step, in which:
 RGB color values and second tristimulus values are produced from a set of three or more training samples, and   a 3×3 transformation matrix which transforms the RGB color values into the first tristimulus values is found such that a deviation of the first tristimulus values from the second tristimulus values is minimized.   
     
     
         7 . The method of  claim 1 , wherein the tristimulus correction is derived by finding a diagonal 3×3 correction matrix which transforms the first tristimulus values of the subset of tristimulus values into corrected tristimulus values such that a deviation of the corrected tristimulus values from the second tristimulus values is minimized. 
     
     
         8 . The method of  claim 1 , wherein the sample is a matrix display. 
     
     
         9 . The method of  claim 1 , further comprising measurement of a temporal variation of a photometric parameter of the sample. 
     
     
         10 . An imaging colorimeter system capable of two-dimensional, spatially resolved measurement of tristimulus values of light emitted from a plurality of positions on a sample, comprising:
 a beam splitter splitting the light emitted from the sample into a first portion and a second portion;   an RGB camera receiving the first portion of the light and producing a two-dimensional map of RGB color values;   a controller transforming the RGB color values into first tristimulus values to produce a map of tristimulus values; and   a colorimeter receiving the second portion of the light and producing second tristimulus values,   wherein the controller is further arranged to:   derive a tristimulus correction by comparing the second tristimulus values with at least a subset of the first tristimulus values; and   apply the tristimulus correction to the first tristimulus values to produce a corrected map of tristimulus values.   
     
     
         11 . The system of  claim 10 , wherein the colorimeter is a photoelectric colorimeter comprising a set of at least three color filters and one or more photo sensors. 
     
     
         12 . The system of  claim 10 , wherein the colorimeter is a spectral photometer. 
     
     
         13 . The method of  claim 3 , wherein the transformation for transforming the RGB color values into the first tristimulus values is derived in a prior training step, in which:
 RGB color values and second tristimulus values are produced from a set of three or more training samples, and   a 3×3 transformation matrix which transforms the RGB color values into the first tristimulus values is found such that a deviation of the first tristimulus values from the second tristimulus values is minimized.   
     
     
         14 . The method of  claim 3 , wherein the tristimulus correction is derived by finding a diagonal 3×3 correction matrix which transforms the first tristimulus values of the subset of tristimulus values into corrected tristimulus values such that a deviation of the corrected tristimulus values from the second tristimulus values is minimized. 
     
     
         15 . The method of  claim 13 , wherein the colorimeter is a photoelectric colorimeter comprising a set of at least three color filters and one or more photo sensors. 
     
     
         16 . The method of  claim 13 , wherein the colorimeter is a spectral photometer. 
     
     
         17 . The method of  claim 14 , wherein the colorimeter is a spectral photometer. 
     
     
         18 . The method of  claim 13 , wherein the sample is a matrix display. 
     
     
         19 . The method of  claim 14 , wherein the sample is a matrix display. 
     
     
         20 . The method of  claim 13 , further comprising measurement of a temporal variation of a photometric parameter of the sample.