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<strong>Veritas</strong> <strong>et</strong> <strong>Visus</strong> <strong>Display</strong> <strong>Standard</strong> February 2009<br />
Luminance and Color Measurement for LED Backlights with a Hyperspectral Camera<br />
Hsiang-Han Hsu, and Yu-Ping Lan, Industrial Technology Research Institute, Hsinchu, Taiwan<br />
Chieh-Hung Lai, ISUZU Optics Corp., Hsinchu, Taiwan<br />
A calibrated hyperspectral camera is used for luminance and color measurements for the entire surface of LED<br />
backlights. The measurement results are compared and are consistent with the results of point-to-point<br />
measurements of the widely-used Topcon spectroradiom<strong>et</strong>er SR-3A. This new hyperspectral camera demonstrates<br />
the feasibility and reliability of this<br />
application. The results show the maximum<br />
differences in luminance and CIE color<br />
coordinates measurements are 2.9 % and<br />
0.002, respectively. The schematic image<br />
type hyper spectrom<strong>et</strong>er is shown in the<br />
figure. It consists of an objective lens, an<br />
entrance slit and a prism-grating-prism<br />
(PGP) structure. The hyperspectral camera is<br />
a line scanning system with high spectral<br />
resolutions. The line image of the targ<strong>et</strong> is<br />
formed by imaging optics and then projected<br />
on a CCD imaging sensor. The spectral<br />
Light dispersed via PGP structure to CCD image sensor of the<br />
hyperspectral CCD camera<br />
range of the hyperspectral camera is from 380nm to 1100nm. A 1344x1024 12-bit CCD camera (HAMAMATSU<br />
C8484- 05G) was used for the experiment. The entire surface information of the LED backlight is derived by<br />
scanning of the targ<strong>et</strong>. Digital images of the targ<strong>et</strong> are captured by a personal computer via IEEE 1394 interface.<br />
Channel-Dependent GOG Model for Colorim<strong>et</strong>ric Characterization of LCDs<br />
Chun-Hsien Chou, Ray-Chin Wu, Chih-Cheng Fu, Cheng-Chieh Wu, and Shing-Shi Tseng, Tatung University,<br />
Taipei, Taiwan; Chien-Lung Tzou, and Jia-Ming Huang, Chunghwa Picture Tubes, Taipei, Taiwan<br />
Accurate colorim<strong>et</strong>ric characterization is an important step in establishing the color management system for LCDs<br />
to achieve device-independent color reproduction. The gain-offs<strong>et</strong>-gamma (GOG) model that is accurate enough in<br />
describing the tone reproduction curves (TRCs) for CRT displays has been found inadequate for characterizing<br />
LCDs due to mainly channel interaction and non-constancy of channel chromaticity. In this paper, a modified<br />
GOG model that takes channel interaction and backlight leakage into account is proposed to accurately characterize<br />
the TRCs of LCDs. Experimental results indicate that the proposed model outperforms the conventional GOG<br />
model in terms of the CIEDE2000 color difference b<strong>et</strong>ween the XYZ values of the measured color sample and the<br />
estimated XYZ values. The effect of channel interaction is considered in the proposed model by measuring the<br />
param<strong>et</strong>ers of gain and gamma of the GOG model as functions of input digital counts. Experimental results show<br />
that the proposed model outperforms the conventional GOG model and is effective in accurate color reproduction<br />
of LCDs. The proposed model is also believed to be helpful in characterizing the color sequential displays that<br />
show apparent dependence b<strong>et</strong>ween color channels.<br />
Noise and Resolution in a Dual-Layer LCD<br />
Aldo Badano, and Hongye Liang, Center for Devices and Radiological Health, FDA, Silver Spring, Maryland<br />
Luigi Albani, FIMI/Philips, Saronno, Italy<br />
The noise and resolution characteristics of a dual-layer LCD capable of high luminance range are presented with<br />
emphasis on the measurement and analysis m<strong>et</strong>hods considering the parallax effect. The results are compared to an<br />
identical panel with a single-layer structure. The figure shows a single-pixel line displayed in both front and back<br />
layer. As a result of the parallax effect, the lines overlap fairly well at about 15 degrees. The parallax effect is<br />
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