The assessment and characterization of the built-in internal photometer of primary diagnostic monitors

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Abstract

The purpose of this work was to perform the initial evaluation of primary diagnostic monitor (PDM) characteristics following the implementation of New York City quality assurance (NYC QA) regulations on January 1, 2016, and compare the results of the QA measurements performed by an external photometer and the PDM manufacturer's built-in photometer. TG-18 and Society of Motion Picture and Television Engineers test patterns were used to evaluate monitor performance. Overall, 79 PDMs were included in the analysis. The verification of grayscale standard display function (GSDF) calibration, using a built-in photometer, showed that only 2 out of 79 PDMs failed calibration. However, the same measurements performed by the external luminance meter showed that 15 out of 79 monitors had failed GSDF calibration. Measurements of the PDMs maximum luminance (Lmax), using an external photometer showed that 10 out of 53 PDMs calibrated for Lmax = 400 cd/m2 and 17 out of 26 PDMs calibrated for Lmax = 500 cd/m2 do not meet the manufacturer's recommended 10% tolerance limit for the target Lmax calibration. Two PDMs did not pass the Lmax ≥ 350 cd/m2 NYC QA regulations with Lmax = 331 cd/m2 and Lmax = 340 cd/m2. All tested PDMs exceeded the minimum luminance ratio (LR) of 250:1 as required by NYC QA regulations. Measurements taken of Lmax and LR performed by a built-in photometer showed that none of the PDMs had failed the NYC QA regulations. All PDMs passed the luminance uniformity test with a maximum nonuniformity of 17% (according to NYC regulations it must be less than 30%). The luminance uniformity test could only be performed using an external photometer. The evaluation of 79 PDMs of various ages and models demonstrated up to 18% disagreement between luminance measurements performed by the manufacturer's built-in photometer when compared with those performed by an externally calibrated luminance meter. These disagreements were larger for older PDMs.

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