Luminance contrast

Slaghuis WL. 2004. Spatio-temporal luminance contrast sensitivity and visual backward masking in schizophrenia. Exp Brain Res 156 196-211. 

W35 W36 W37 W38 W39 W40 69% Task nature 1 = rough, 2 = moderate, 3 = fine, 4 = very fine Glare/reflection 0 = none, 1 = noticeable, 2 = severe Colour contrast 0 = none, 1 = noticeable, 2 = severe Luminance contrast 0 = none, 1 = noticeable, 2 = severe Task illuminance, foot candles Luminance Task > Midfield > Outerfield = yes... 

Luminous contrast refers to the changing light levels in an environment. For example, one may look at work on a desk that has a certain illumination. The eyes may shift to a different object or location with a much darker or lighter level of illumination. When there is too much difference between the two surfaces, the eyes have difficulty adapting, which may lead to visual errors. 

When the small bowel is distended with positive contrast, the wall is thin, and may be imperceptible but should not measure more that 1-2 mm (Macari and Balthazar 2001). The use of dilute barium and iodinated positive oral contrast agents are particularly well suited in evaluating thin patients without a lot of intr aperitoneal adipose tissues and in oncology patients where implants and lymph-nodes will stand out from the small bowel. A potential limitation of positive oral contrast agents in the evaluation of the small bowel is that mucosal enhancement may be obscured by the luminal contrast and thus the pattern of enhancement, which serves as a primary aid in the differential diagnosis of an abnormal stomach or small bowel segment, may be impaired (Fig. 3.8). 

A color difference ratio allows us not only to evaluate the usual luminance contrast (4.59), but also to evaluate a color purity and the color hue that makes the human eye very sensitive to the variation of CDR. Reference [170] demonstrates the increase by a factor of three of the number of distinguished rows of the display when evaluating by the colorimetry methods. This effect may be understood by the fact that the human eye is more sensitive to the color contrast than to the luminance one, as the hue and the chroma both contribute to the former. Color differences between on and off display states could be optimized by a special choice of polarizers [170-172], concentration of a dichroic dye (guest) in a liquid crystal matrix (host) [166, 173], using the reflective screens [173], etc. Colorimetric evaluations are very useful in the quality control of both the guest host and twist displays [172, 174]. 

The luminance contrast may be defined as the ratio of the difference between the symbol and background luminance, AL to the luminance of the symbol (or background, whichever is more luminous), i.e. 

ISO 9241-302 2008 ergonomics of human-system interaction—part 302 terminology for electronic visual displays Image formation time, monitor coordinate system, luminance contrast... 

Luminance and contrast rendering (values for minimum luminance contrast on the monitor) (a) for direct sunlight condition 2 1... 

The functional component requirements focus on image quality. While the functional requirements for Class V and VI CMS mainly include luminance contrast and blooming, there are several new requirements for Class I-IV CMS due to different... 

It should be noted that some component tests on image quality need vehicle-specific information Standard and extended isotropy range depend on the monitors design viewing direction, which in mm depends on the position of the monitor in relation to the driver s eye point. The new measurement procedme to determine the relevant luminance for the luminance contrast requirement depends also on the vehicle layout (see below). 

While ISO 16505 requires a luminance contrast of 5 1 for night conditions, UN Regulation No. 46 sets out a more severe value of 10 1 (except for systems which include both technologies CMS and mirror) in order to address the needs of older drivers. 

Another aspect influencing the perception in a CMS is the sharpness. From the same MTF(/) curve, the spatial frequency where the MTF(/) value drops to 50 % is taken as the representative spatial frequency characterizing the sharpness of the system. This particular spatial frequency is denoted as MTF50 to define the sharpness requirement. There are several other aspects like edge acuteness or luminance contrast that also affect the perceptual sharpness. 

The specific color and orientation tuning of neurons underpins the separation of color and edge information paths in the HVS, which motivates the separation for color and luminance in image manipulation in luminance contrast and hue. 

Sharpness and shading are assessed by the secondary luminance contrast pathway. Besides the cones spacing, this pathway defines the spatial resolution and... 

Motion perception relies on luminance contrast decomposition of the visual pathway as well. Specifically tuned neurons in the visual cortex are sensitive to edges moving in a defined direction. Experimental findings indicate that this process does not necessarily require apparent motion [17]. This emerges the question if these neuronal structures can be stimulated by still images. 

Mirrors depict the object luminance according to its degree of reflection. The object luminance, which is dependent on the degree of reflection, is perceived by the eye, however, diminished by the transmittance of the side window The maximum luminance of moniUHs is limited. Ambient light can diminish the luminance contrast and the colour saturation on the monitor. Also, at night, the monitor has a basic luminance greater than 0 cd/m ... 

Modulation - In general, the changes in one wave train caused by another in thermal scanning and imaging, image luminant contrast (L ax - Lmin)/(Lmax + Lmin)-... 

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