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

Shiiba, Takuro; Tanoue, Naofumi; Tateoka, Shinji; Maeda, Masaji; Fukai, Tomoki; Morishita, Junji

doi:10.1007/s12194-009-0078-x

Cited by 4 publications

(3 citation statements)

References 3 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…The Minolta LS‐100 has a circular measurement area covering a 1° viewing angle while the viewfinder covers 9°. The influence of light from the viewfinder outside the measurement area is normally small but can be substantial when measuring a small dark area surrounded by bright regions 23 . The normal closest focusing distance of the luminance meter is 1 m, but due to the head‐simulating position closer to the screen, a close‐up lens (lens 135) had to be used.…”

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

“…The influence of light from the viewfinder outside the measurement area is normally small but can be substantial when measuring a small dark area surrounded by bright regions. 23 The normal closest focusing distance of the luminance meter is 1 m,but due to the head-simulating position closer to the screen, a close-up lens (lens 135) had to be used.Due to light attenuation in the lens, all measured values were multiplied with 1.05, as specified by the Minolta user manual. Using this lens had another positive effect-the entire viewfinder field of vision was within the boundaries given by the center homogenous area of the test image, thereby reducing the effect of bright light from outside the measurement area.…”

Section: Luminance Measurements and Test Pattern Generationmentioning

confidence: 99%

See 2 more Smart Citations

Perceived contrast on displays with different luminance ranges

Sund

2022

Medical Physics

View full text Add to dashboard Cite

Medical displays are fundamental in today's healthcare since they provide the link between digitally stored data and the human clinician, and it is thus important that the transfer of information is as effective and reliable as possible. Contrast perception in viewed images is complex due to the nature of the human visual system, and the luminance distribution in the viewed scene plays a major role. Standards and guidelines concerning medical displays are important as they set a baseline image quality. However, as the number of imaging applications as well as display technology has evolved rapidly during the past decades, there may be possible uses not foreseen in the current guidelines. Bright screens may perform as good in bright rooms as less bright displays do in dark rooms, but current guidelines are likely to favor dark rooms due to historical reasons. The purpose of this study was to determine the limits of contrast perception in three very different lighting conditions and relate the outcome to guideline recommendations. Methods: Three different display luminance settings were studied, 1-250, 6-500, and 12-750 cd/m 2 with luminance ratios of 250, 85, and 62, respectively. Although the luminance ratios, black levels, and white levels were different, they all covered the same number of just noticeable differences (JNDs). By using a two-alternative forced-choice method, contrast thresholds were determined at dark, mid-gray, and bright pixel values for all luminance settings using bar patterns with two different spatial frequencies. In total, 18 contrast thresholds were determined by each of the 10 observers. Results: The contrast thresholds for the low-frequency patterns were close to 0.5 JNDs and there were no systematic differences between the three luminance conditions at any of the pixel values. The high-frequency patterns required almost 10 times higher contrast where the highest contrast threshold (worst visibility) was obtained for the luminance setting 1-250 cd/m 2 at the dark pixel value. Conclusions: The differences between the three luminance conditions were mostly minor, which indicate that display settings with low luminance ratios and high minimum luminance levels can be used without compromising displayed image contrast. The number of JNDs enclosed by the luminance range of a display is a reliable metric for global perceived contrast. Luminance ratios are limited regarding the ability to detect low contrast objects when there are large differences in luminance, although they can still be used within a relatively smallThis is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

show abstract

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Luminance Measurements and Test Pattern Generationmentioning

confidence: 99%

See 1 more Smart Citation

Perceived contrast on displays with different luminance ranges

Sund

2022

Medical Physics

View full text Add to dashboard Cite

show abstract

A preliminary study for exploring the luminance ratio of liquid-crystal displays required for display of radiographs

Takarabe

Morishita

Yabuuchi

et al. 2013

Radiol Phys Technol

View full text Add to dashboard Cite

Medical-grade liquid-crystal displays (LCDs) with high contrast ratio (CR) values have recently been developed and become available for soft-copy reading. When the LCD is used under ambient light conditions, the luminance ratio (LR) is a more appropriate indicator than the CR. Our aim was to explore the LR required for LCDs for soft-copy reading by comparing the effective LR values with the LR of the LCD. We defined "the luminance ratio in an image (LRimg)", the ratio of the maximum to minimum luminance in a radiograph displayed on the LCD, as the effective LR values required for the LCD. The maximum LRimg values in chest radiographs and those in mammograms ranged from 109 to 143 and 372 to 431, respectively. The LR of the LCD was higher than the LRimg values of the radiographs. Our results indicate that currently available medical-grade LCDs have enough LR for display of radiographs.

show abstract

Effect of fluorescent lighting on the color of liquid-crystal displays

Yano

Morishita

Akamine

et al. 2014

Radiol Phys Technol

View full text Add to dashboard Cite

Liquid-crystal displays (LCDs) are used for displaying medical images under various illuminance conditions and with ambient-lighting colors. Our purpose in this study was to understand the variations of the chromaticity in LCDs under different fluorescent lighting conditions. The variation of chromaticity of LCDs at a white point consisting of equivalent pixel value in Red, Green, and Blue was examined under different types of fluorescent lighting. The direction of changes in the chromaticity diagram shifted to the color of each fluorescent lighting. When the differences in chromaticity (∆u'v') increased, the observers' confidence levels in distinguishing color differences also increased. When the luminance of the LCD increased, observers' sensitivities for recognizing differences in chromaticity also increased as compared to observers' sensitivities at lower luminances. Our results indicate that observers recognized slightly yellowish colors even if ∆u'v' was less than 0.01; thus, observers could perceive differences in chromaticity. These results could provide important and relevant information with regard to better ambient lighting conditions in an image-reading room.

show abstract

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

Cited by 4 publications

References 3 publications

Perceived contrast on displays with different luminance ranges

Perceived contrast on displays with different luminance ranges

A preliminary study for exploring the luminance ratio of liquid-crystal displays required for display of radiographs

Effect of fluorescent lighting on the color of liquid-crystal displays

Contact Info

Product

Resources

About