HP LP2480ZX User Manual page 46

Figure A-7
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) ≤ A
Y = I/A
1
For input values (I) > A
Y = [(I + A )/(1 + A
2
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 A , A , and A
0 2
for the standard color spaces or output device specifications supported by the LP2480zx are listed in
the table below.
Table A-3 Response Curve Constants for Various Color Spaces
Color space
sRGB
ITU-R BT.709
SMPTE-C
Adobe® RGB
DCI-P3
40 Appendix A Advanced Color Management Features and Usage
Low Linear Region Response Curve
:
0
'
0
)] γ
3
parameters to zero, and A
3
A
0
0.04045
0.081
0.081
0
0
to a value of 1.0. The values used to describe the response
1
A A
1 2
12.92 0.055
4.50 0.099
4.50 0.099
1 0
1 0
A gamma (γ)
3
0.055 2.4
0.099 2.22222
0.099 2.22222
0 2.19922
0 2.6