NEC PA231W Betriebsanweisung PDF herunterladen (Seite 15)

15 | SPECTRAVIEW II - USER’S GUIDE

Use Scale Factor - The DICOM response curve shape is based on the measured black level and

Intensity. If the black level or Intensity of the display changes, then the shape of the DICOM response

curve also changes. If a display is not expected to be re-calibrated for a period of several months, this

feature can be used to increase the longevity of the DICOM calibration using the knowledge that the

displays brightness will decrease slightly as it ages. By scaling the black level and Intensity values

used to calculate the DICOM response curve, using the Use Scale Factor value, the response curve

can be based on the lower future black level and Intensity. The value used will depend on the display,

its usage, and the time interval until it is expected to next be re-calibrated.

Custom Curve - Advanced and custom response curves can be selected from presets or created by

importing a table of values. Click the Edit... button to open the Custom Gamma Curve dialog.

Intensity

The Intensity selects the luminance or “brightness” of white for the calibration. Options are:

Maximum possible - calibrates the display to the maximum possible luminance that it can achieve.

The actual value achieved will depend on the display’s type, its age and the white point used. This is

not recommended when trying to exactly match two or more displays, since there may be a difference

between what Intensity each display can achieve.

Specic Level - calibrates the display’s Intensity to a specied target value. If the display can not

achieve the specied value, it will be calibrated to the closest possible Intensity, and a message will be

displayed after the calibration has completed.

Note: If you are unsure about what level to use for the Specic Level for a particular application, it is possible

to interactively adjust both the White Point and Intensity using the Visual Match feature in the Custom White

Point dialog.

Contrast Ratio

Contrast Ratio allows a particular contrast ratio to be used if necessary. The contrast ratio is the ratio of white

to black luminance.

Selecting Monitor Default will calibrate the display to the

highest possible contrast ratio, which is limited by the display

technology, the selected White Point, Intensity value, and

other factors.

In some applications, such as simulating low contrast images

such as in newsprint, it is useful to have a lower contrast ratio

than the display’s native value. Contrast Ratios in the range

of 50:1 to 500:1 can be selected.

Note: If the selected contrast ratio is higher than what the

display is actually capable of achieving, then the display will

calibrate to the highest possible contrast ratio. If a specic

Contrast Ratio is selected, it is recommended that the

number of Calibration and Measurement Steps be set to at

least 32 in the Preferences dialog.

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NEC PA231W Betriebsanweisung Seite 15