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Using the controls for gamma, contrast and brightness, the gamma correction on an LCD can only be done for one specific vertical viewing angle, which implies one specific horizontal line on the monitor, at one specific brightness and contrast level. An ICC profile allows one to adjust the monitor for several brightness levels. The quality (and ...
The correct identification of small letters requires the letter size be about 18-30 cpd. [14] Contrast threshold can be defined as the minimum contrast that can be resolved by the patient. Contrast sensitivity is typically expressed as the reciprocal of the threshold contrast for detection of a given pattern (i.e., 1 ÷ contrast threshold). [15]
The dataset [255,0,0] signals only a device instruction, not a specific color. This instruction [R,G,B]=[255,0,0] then causes the connected display to show Red at the maximum achievable brightness [255], while the Green and Blue components of the display remain dark [0]. The resultant color being displayed, however, depends on two main factors:
Many methods exist for color balancing. Setting a button on a camera is a way for the user to indicate to the processor the nature of the scene lighting. Another option on some cameras is a button which one may press when the camera is pointed at a gray card or other neutral colored object. This captures an image of the ambient light, which ...
[23] [24] The HDR display must have either a peak brightness of over 1000 cd/m 2 and a black level less than 0.05 cd/m 2 (a contrast ratio of at least 20,000:1) or a peak brightness of over 540 cd/m 2 and a black level less than 0.0005 cd/m 2 (a contrast ratio of at least 1,080,000:1).
The image has been deliberately overexposed by +1 EV to compensate for the bright sunlight and the exposure time calculated by the camera's program automatic metering is still 1/320 s. The purpose of an exposure meter is to estimate the subject's mid-tone luminance and indicate the camera exposure settings required to record this as a mid-tone ...
A flat-field image is acquired by imaging a uniformly-illuminated screen, thus producing an image of uniform color and brightness across the frame. For handheld cameras, the screen could be a piece of paper at arm's length, but a telescope will frequently image a clear patch of sky at twilight, when the illumination is uniform and there are few ...
In the field, sharpness is affected by camera shake (a good tripod can be helpful), focus accuracy, and atmospheric disturbances (thermal effects and aerosols). Lost sharpness can be restored by sharpening, but sharpening has limits. Oversharpening, can degrade image quality by causing "halos" to appear near contrast boundaries.