Effect of test patterns on measurement of the luminance of LCD devices by use of a telescopic-type luminance meter

Abstract

Quality assurance of electronic display devices is important for maintaining reliable soft-copy image interpretations. This paper presents effects of test patterns on measurement of the luminance of liquid-crystal display (LCD) devices by use of a telescopic-type luminance meter. The luminance for different types of test patterns having different backgrounds and measurement areas was measured and compared with the results obtained with AAPM task group-18 (TG-18) LN test patterns. The luminance measured for the test patterns with a black background was lower than that measured for TG-18 LN test patterns due to the light emitted from the outside the focused area of the telescopic-type luminance meter. Also, the luminance obtained with smaller measurement areas indicated lower luminance. These tendencies were particularly obvious at low luminance. The luminance of the LCD device by use of a telescopic-type luminance meter should be measured with test patterns that have a black background and a smaller measurement area than that for the TG-18 LN test patterns.

Effects of ambient-light correction in luminance measurements of liquid-crystal display monitors by use of a telescopic-type luminance meter

“…In order further to reduce the influence of the stray light of the telescopic-type luminance meter, it is necessary to use a mask test pattern with a central test region that is slightly greater than the focused area of the telescopic-type luminance meter. However, the reproducibility of the luminance measurement will be decreased [9].…”

“…Test patterns used for the luminance measurement were TG18-BN 01-18, which are alternative test patterns of TG18-LN 01-18, and which are available on the WEB site of the Japan Industries Association of Radiological Systems (JIRA) [11]. These test patterns, which have eighteen digital-driving levels (DDLs) with a black background [9], were used for measurements of the luminance and the contrast response based on the guidelines of the JESRA X-0093 -2005 . A hand-made baffled tube (7 9 7 9 135 cm) with black interior was used for avoiding ambient light.…”

“…A near-range luminance meter may be useful for calibration of the gamma of the LCD monitor because it is not affected by ambient-lighting conditions. On the other hand, for a telescopic-type luminance meter, which is commonly used at present for the measurement of luminance, the influence of ambient light [8] and the light emitted from outside the focused area of the meter [9], namely, the stray light, cannot be ignored. The guidelines of JESRA X-0093 -2005 recommend no-ambient-lighting conditions for luminance measurements if a telescopic-type luminance meter is used.…”

“…However, it is difficult to have no-ambient-lighting conditions at most hospitals or medical centers. So far, publications regarding the luminance measurement of the LCD monitor are scarce [8][9][10].…”

Comparison of viewing angle and observer performances in different types of liquid-crystal display monitors

“…A telescopic-type luminance meter (LS-100, Konica Minolta, Tokyo, Japan) was used for the measurements of luminance of the LCD monitors. The luminance performance of the LCD monitors as a function of viewing angle, i.e., -60°, -50°, -40°, -30°, -20°, -10°, 0°, 10°, 20°, 30°, 40°, 50°, and 60°, was measured using the TG-BN test patterns (modified TG-LN test patterns with a black background [11] and currently available on the WEB) [9] in different directions (horizontal, vertical, and diagonal directions). TG-BN test patterns consist of 18 patterns (TG-BN 1-18) with different central-area brightnesses.…”