The difference between external and built-in measurements of white level luminance, calculated as a percent of the value reported by the built-in luminance meter, is plotted against BLH for 93 displays used for primary image interpretation. As these displays exceed their backlight warranty (20 000 BLH for model MFGD 3420 and 25 000 BLH for model MDCG 3120-CB) disagreement between the measured and reported values becomes more common and the magnitude of the differences increases.
A Bland-Altman plot of agreement between external and built-in luminance measurements for 66 displays with less than 25 000 BLH. The difference in measurement (ordinate) is plotted against the target luminance (abscissa). The dashed line represents the mean difference in luminance (5.84%), and the solid lines represent ±2 standard deviations (σ = 3.49%). The mean difference was found to be statistically significant based on a two-tailed t-test (p < 0.001).
The luminance measured using the RaySafe Xi meter is plotted against the luminance measured using the Chroma5 meter over a range of driving levels. Each data point is the mean of five independent measurements. These measurements were observed to be highly correlated (r = 0.999) with the solid black line representing a linear fit to the data. The dashed gray line represents the line of identity.
A Bland-Altman plot of agreement between the RaySafe Xi luminance meter and the Chroma5 luminance meter. The difference in measurement (ordinate) is plotted against the mean luminance (abscissa). The dashed line represents the mean difference in luminance (0.37%), and the solid lines represent ±2 standard deviations (σ = 0.61%). The mean difference was found to be statistically significant based on a paired t-test (p = 0.022).
Grayscale maps of luminance for three different displays—Model MDCG 3120-CB with 579 BLH (a), Model MDCG 3120-CB with 39 389 BLH (b), and Model MFGD 3420 with 42 333 BLH (c). The white level luminance was measured at 48 evenly spaced positions across the face of the display. The measured values were normalized by the value in the center of the display; the normalized values were used to generate gray-scale maps of luminance uniformity. The black squares in the lower right corner of each grayscale map represent the approximate position of the built-in luminance meter.
The mean of five independent luminance measurements using RaySafe Xi and Chroma5 luminance meters are listed as well as the standard deviation and COV. Measurements were made using a subset of the TG-18 LN test patterns with luminance values ranging from 0.66 to 528.18 cd/m2. The white level for the display tested was 500 cd/m2. The mean COV was 0.17% and 0.22% for the RaySafe and Chroma5 meters, respectively.
Luminance reported by the built-in meter and measured in the center and four corners using a RaySafe Xi luminance meter is listed for ten displays with less than 800 BLH, six displays with greater than 35 000 BLH for model MDCG 3120-CB, and ten displays with greater than 35 000 BLH for model MFGD 3420. MLD has been calculated for each display and is listed along with its individual BLH. For model MDCG 3120-CB, the mean MLD was 9.5% ± 4.3% and 11.2% ± 6.5% for displays with less than 800 BLH and greater than 35 000 BLH, respectively. This difference was not found to be statistically significant (p = 0.59) based on a two tailed t-test. For model MFGD 3420, the mean MLD for displays with greater than 35 000 BLH was 42.5% ± 9.1%. No displays with less than 800 BLH were available for this model.
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