Figure A-7Low Linear Region Response Curve

A generalized model for the display response curve accommodating the addition of a linear section as shown above thus requires the specification of four parameters in addition to the “gamma” exponent value:

For input values (I) ≤ A0:

Y = I/A1

For input values (I) > A0′

Y = [(I + A2)/(1 + A3)]γ

The response of the LP2480zx is automatically set to the correct standard as part of the color-space selection, using either the on-screen display (OSD) or using the HP Display Assistant software, or using the optional HP/X-Rite color calibration tools. Independently programming a custom response (as in the case of the user-defined custom color space preset) requires use of the HP/X-Rite calibration tools. Using the software provided with this calibration product, the display response may be programmed using the four-value-plus-gamma model described above.

Several of the standard color space specifications supported by the LP2480zx require the use of the “four-value” model, as they include a linear section in the response curve as described above. Of course, even the simple “gamma-only” model may be accommodated within the four-value model, by setting the A0, A2, and A3 parameters to zero, and A1 to a value of 1.0. The values used to describe the response

for the standard color spaces or output device specifications supported by the LP2480zx are listed in the table below.

Table A-3Response Curve Constants for Various Color Spaces

Color space

A0

A1

A2

A3

gamma (γ)

sRGB

0.04045

12.92

0.055

0.055

2.4

 

 

 

 

 

 

ITU-R BT.709

0.081

4.50

0.099

0.099

2.22222

 

 

 

 

 

 

SMPTE-C

0.081

4.50

0.099

0.099

2.22222

 

 

 

 

 

 

Adobe® RGB

0

1

0

0

2.19922

 

 

 

 

 

 

DCI-P3

0

1

0

0

2.6

 

 

 

 

 

 

40 Appendix A Advanced Color Management Features and Usage