Apple Mac OS X Server System Imaging and Software Update Administration For Version 10.4 or Later Manual de usuario descargar pdf (Pagina 14)

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Integrating Mac Systems into

a Medical IT Infrastructure

The Apple Cinema Display does not allow direct storage of a custom LUT in its hard-

ware, so calibration of these displays requires an ICC prole.

We applied this prole

at the graphics adapter level via the appropriate System Preferences pane.

The basICColor RAY application (see Figure 7), a commercial application available from

Color Solutions, allowed us to calibrate according to a DICOM or CIE LUT using auto-

matic measurement procedures with dierent colorimeters and luminance meters. We

calibrated our 30-inch Apple Cinema Displays to a DICOM LUT

using a white point of

6500K. We chose the lowest possible black point to achieve the greatest contrast. The

maximum luminance was set to be 50 cd/m

higher than the minimum specied by

the DIN 6868-57 directive. This ensured that the luminance at measurement distance

would not fall below Category A and B limits between service intervals. (On 8-bit

Apple Cinema Displays, it is advisable to reduce maximum luminance to leave enough

bandwidth to represent darker gray levels.)

After calibrating grayscale using 250 cd/m

as maximum luminance, the team

achieved measured grayscale presentation results that met the GSDF requirement.

(See Figure 8.)

Gray level representation (ACD 30˝ calibrated to 250 cd/m

)

Gray level (%)

300,00

250,00

Luminance (cd/m

)

200,00

150,00

100,00

50,00

0,00

100 20 30 40 50

70 80 90 10060

Measured

Required (GSDF)

Figure 8: After calibration, the 30-inch Apple Cinema Display matches the required curve of gray

level representation.

Eect of antireective coating. Like other at panel displays, the Apple Cinema

Display features an antireective coating. Designed to diuse ambient light, the

coating can coarsen granulation, which can produce a “mother of pearl” eect

when viewing bright areas in chest X-ray images. However, the coating did not

aect extremity X-ray, CT, or MRI images.

Post-calibration tests. After calibration, we performed conformity tests on the displays.

Table 2 shows the results of the two 30-inch Apple Cinema Displays, which were

measured with the CD-LUX densitometer in a specic distance and an ambient light

of approximately 6 lux.

Table 2: Results of conformity tests on the two calibrated 30-inch Apple Cinema Displays

(The accepted standards for each test are listed in italics.)

Maximum Luminance

[cd/m

]

Maximum Contrast Inhomogeneity

Apple Cinema Display 1 Result: 231.8

Category A target: > 200

Category B target: > 120

Result: 331.14

Category A target: > 100

Category B target: > 40

Result: 14.6%

Category A target: ± 15%

Category B target: ± 20%

Figure 7: The basICColor RAY application uses

automatic measurement procedures to calibrate

with dierent colorimeters and luminance meters.

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