<title>NIST calibration facility for display colorimeters</title>

Abstract

A calibration facility has been developed at the National Institute of Standards and Technology (NIST) to address the need for high accuracy color measurements of displays. Calibration services are planned for colorimeters and spectroradiometers, tailored to display measurements. A key component of the facility, a reference spectroradiometer, has been developed and its uncertainty for display measurements estimated using a series of computer simulations. The simulations predict that the reference spectroradiometer - corrected for wavelength error and variable bandpass - can measure any color of a cathode ray tube or liquid crystal display with a combined standard uncertainty of approximately 0.001 in chromaticity (x,y) and 1 percent in luminance (Y). In addition a new matrix correction technique has been developed as a means to transfer the calibration from the reference instrument to a test instrument. Using the four-color method, the residual errors with the calibrated instrument for one type of display are reduced to within 0.001 in x,y with respect to the reference instrument. To evaluate the overall performance of the system, commercial instruments - spectroradiometers and tristimulus colorimeter - were calibrated against the reference instrument, measuring both a CRT and an LCD display. The results show that calibrated target instruments can measure various colors of a particular display with a combined standard uncertainty of approximately 0.002 in x,y and 2 percent in Y.