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Flight Deck Human Factors
Published in Steven J. Landry, Handbook of Human Factors in Air Transportation Systems, 2017
Michelle Yeh, Thomas R. Chidester, Thomas E. Nesthus
Legibility: The legibility of information on an electronic display is influenced by several factors including the viewing angle, pixel density, and contrast ratio (Nelson et al., 2014; Yeh & Chandra, 2005). Some symbols may have fine details that are difficult to see when viewed off-angle or under degraded display conditions. The viewing angle refers to the angle at which a symbol subtends the eye, measured in degrees of arc, and captures the relationship between symbol size and viewing distance. That is, a small symbol viewed at a close distance could have the same visual angle as a larger symbol viewed from farther away. The pixel density describes the number of pixels per inch of a display. Five pixels are needed to draw a letter on a display, but six pixels are needed for the letter to be “fully recognizable” (Nelson et al., 2014). Finally, contrast ratio describes the difference in luminance between the symbol and the background. Contrast ratio varies depending on the display hardware, the information being shown, and the amount of light on the flight deck.
Vision
Published in Anne McLaughlin, Richard Pak, Designing Displays for Older Adults, 2020
Computer displays are made up of millions of individual elements or pixels. Pixel density is a measure of how closely the pixels are arranged on the display. It is indicated in pixels per (per square) inch (PPI). Pixel density affects how sharp a display is perceived as well as its readability (Figure 2.10). A low-density display will appear blocky and jagged whereas a higher pixel density display will appear sharper and smoother. The analog to PPI in the print world is dots per inch (DPI). Sometimes, PPI and DPI are used interchangeably, such as HiDPI displays, which are simply displays with very high pixel densities (e.g., Apple’s Retina displays).
Video Display Distortion Mechanisms and Analysis
Published in Jerry C. Whitaker, Electronic Systems Maintenance Handbook, 2017
Pixel density is a parameter closely related to resolution, stated in terms of pixels per linear distance. Pixel density specifies how closely the pixel elements are spaced on a given display. It follows that a display with a given pixel format will not provide the same pixel density (resolution) on a large size screen—such as 19-in. diagonal—as on a small size screen—such as 12-in. diagonal.
Recent progress of organic light-emitting diode microdisplays for augmented reality/virtual reality applications
Published in Journal of Information Display, 2022
High luminance is a very important factor of outdoor display applications but a weak point of OLED microdisplays. A tandem structure stacks OLED units and thus, generally increases the luminance and current efficiency of OLED devices [32]. However, it needs higher driving voltages as the number of OLED units stacked increases. For a high driving voltage, the size of the transistor should be increased, but a large transistor decreases the pixel density of the display panel. In 2019, Cho et al. adopted a two-stack white tandem structure for OLED microdisplays, as shown in Figure 4(a) [33]. They optically optimized a device structure using optical simulation and reduced the driving voltage using p- and n-doped transporting layers. Although an electrical doping method typically improves the performance of OLEDs [33,34], the electrical crosstalk of the subpixels should be considered when the doping concentration is determined due to the very small pixel pitch in OLED microdisplays. Their white device exhibited a maximum luminance of 20,000 cd/m2 at 9 V, and a white OLED microdisplay that had a 2,350 ppi resolution with a maximum luminance of 3,000 cd/m2 was demonstrated, as shown in Figure 4(b). In 2020, Hamar et al. also applied a tandem structure to OLED microdisplays [35]. They demonstrated OLED microdisplays using three-, four-, and five-stack tandem structures, as shown in Figure 4(c). As the stack number increases, the lifetime of OLEDs is dramatically enhanced, as shown in Figure 4(d). Their panel resolution was WUXGA and the RGBW pixel structure was used for higher luminance due to the unfiltered white subpixel.
Path Planning of Unmanned Aerial Systems for Visual Inspection of Power Transmission Lines and Towers
Published in IETE Journal of Research, 2023
M. D. Faiyaz Ahmed, J. C. Mohanta, Alok Sanyal, Pankaj Singh Yadav
The resolution of the image (camera configuration) is the most common method of evaluating image quality ratio (in this scenario: 12 megapixels). Despite this, pixel density is not a reliable way to assess the image quality of a feature in an image. To overcome this, authors recommend using spatial resolution, which explains the size of the image's smallest visible object.