China
Africa
Explore chapters and articles related to this topic
Vision
Published in Anne McLaughlin, Richard Pak, Designing Displays for Older Adults, 2020
Contrast ratio is a ratio, or comparison, of the brightest (white) and darkest (black) parts of a display. The ratio is usually indicated using two numbers: XXX:YYY where XXX is the brightness level (in arbitrary units) of the brightest part and YYY is the calibrated brightness level of the darkest part. A display with a contrast ratio of 500:1 means that the white is 500 times brighter than the darkest portion of the display (black) and indicates a greater perceived contrast. For example, text will stand out from a background more clearly at 500:1 than in a display with a low contrast ratio (150:1). A high contrast ratio also helps with the display of subtle shades of gray or color. Cathode ray tube (CRT) and e-paper displays have the highest contrast ratio, whereas LCDs can have a medium to low contrast ratio.
Transparent Electrode for OLEDs
Published in Zhigang Rick Li, Organic Light-Emitting Materials and Devices, 2017
The contrast ratio (CR) of an OLED display is very much dependent on the ambient lighting conditions. The actual CR for an OLED display is based on the applications and differs depending on the products, such as car audio, cell phone, etc. Usually for indoor applications, a CR of >10–20:1 is sufficient. According to UDC OLED Technology Roadmap 2001–2010, the targeted CR for OLED displays (300 cd/m2, under 500 lux) is expected to be 50:1, 100:1, and 200:1 for 2004, 2007, and 2010, respectively. In a pixilated device, CR can be defined as [91] () CR=Lon+RL×LambientLoff+RL×Lambient
Color in Digital Cinema
Published in Charles S. Swartz, Understanding Digital Cinema, 2004
Contrast ratio. Contrast ratio—or more technically, simultaneous contrast ratio—is the ratio of luminance between the lightest and darkest regions of an original scene or a reproduced image. Contrast ratio is a major determinant of image quality. A dark viewing environment is more demanding of image coding than a light viewing environment. Projected cinema film can deliver to the viewer a contrast ratio approaching 100:1, considerably better than television (about 30:1), which is in turn better than viewing in an office environment (about 15:1). Sequential contrast ratio is the ratio of intensity between the lightest and darkest achievable reproduced luminance levels, where these levels need not be displayed simultaneously. The sequential contrast ratio for a given display system is typically much higher than its simultaneous contrast ratio. While high sequential contrast ratio is important, simultaneous contrast ratio is the more important measure.
Formulation and characterization of gelatin methacrylamide-hydroxypropyl methacrylate based bioink for bioprinting applications
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Nithusha Kallingal, Rashmi Ramakrishnan, Kalliyana Krishnan V
The opacity of G100HP0, G95HP05, G90HP10, G80HP20 and G60HP40 hydrogels was measured by a procedure prescribed by American Dental Association (ADA; USA specification 27) using an opacity display chart and by measuring the contrast ratios. The contrast ratio is the ratio of the luminance of the brightest color (white) to that of the darkest color (black) that the sample is capable of producing. Briefly, 1 mm thick hydrogel samples were prepared by casting in a Teflon mold. After gelation, it was immersed in distilled water for 24 h at 37 ± 1 °C to separate the samples from the mold. The samples were placed on the surface of a black and white display chart and compared the opacities of specimen with the three opal glass standard (Delrin) having C0.70 values of 0.35, 0.55 and 0.95, respectively. A film of distilled water was used to cover the specimens and the standards. The opacities of the samples either equal to or between the opacities of standard were visually observed.
Improved Particle Swarm Optimization for Detection of Pancreatic Tumor using Split and Merge Algorithm
Published in Computer Methods in Biomechanics and Biomedical Engineering: Imaging & Visualization, 2022
Bhawna Dhruv, Neetu Mittal, Megha Modi
Contrast: For different types of images, the difference in luminescence that makes an object visible is known as contrast, and it may be computed as the illumination difference between two objects. The variation in colour that initiates object presentation is called contrast (Dhruv et al. 2019). Contrast is calculated in the actual world by comparing the luminance of an object to other objects in the same visual field. The image has low entropy and weak contrast when the difference between its maximum and minimum intensities is relatively small. The contrast ratio is defined as the image’s highest level of contrast. The idea is to boost an image’s contrast so that it is easier to understand. The contrast is a proportion of Luminance difference/Average luminance of the type. This also implies that if the average luminance is high, a minor difference can be overlooked, however if the average brightness is low, the difference cannot be overlooked. Contrast may be computed using the equation 8.
Easily reproducible top-emitting organic light-emitting devices for microdisplays adapted to aluminum contact from the standard CMOS processes
Published in Journal of Information Display, 2020
OLED microdisplays without any high-voltage CMOS scheme usually require a low driving voltage to match the output of the CMOS circuits, and a sufficiently high luminous efficacy to reduce the power consumption. To address this issue, RGB TEOLEDs with freshly evaporated metallic anodes were fabricated by employing red and green phosphorescent emitters and the blue fluorescent emitter, respectively (see Figure 1(a)). The capping layer (anti-reflective layer) was designed and adjusted to fit the maximum light outcoupling of each color in the forward direction. Meanwhile, the contrast ratio could be enhanced. As can be seen in Figure 1(b), the driving voltages for the red and green TEOLEDs were approximately 2.76 and 3.00 V at 1000 cd/m2 luminance, respectively. Due to the lower exciton utilization ability of the blue fluorescent emitter, however, which could harvest only the singlet excitons, the driving voltage at the same brightness was 3.78 V at most. The EL peak wavelengths of the RGB TEOLEDs were 604, 516, and 460 nm, respectively, as illustrated in Figure 1(c).