Abstract

We investigate the effect of new point spread functions (PSFs) on the uniformity and contrast of high dynamic range displays that use local dimming of LEDs to yield a large dynamic range. A PSF shaped like a quadratic B-spline was hypothesized to create a uniform brightness backlight, as well as producing linear and quadratic gradients, while maintaining a very high contrast. We have found a practical optical structure to produce such a PSF, yielding a nonuniformity of only ±0.8%, while enabling a contrast ratio of 51 and 331 over distances of one and two unit cell spacings, respectively.

© 2013 Optical Society of America

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References

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  1. C. Lai and C. Tsai, “Backlight power reduction and image contrast enhancement using adaptive dimming for global backlight applications,” IEEE Trans. Consum. Electron. 54, 669–674 (2008).
    [CrossRef]
  2. H. Chen, J. Sung, T. Ha, and Y. Park, “Locally pixel-compensated backlight dimming for improving contrast on LED backlit LCDs,” SID Symp. Dig. Technol. Papers 38, 1339–1342 (2007).
    [CrossRef]
  3. H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
    [CrossRef]
  4. W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
    [CrossRef]
  5. R. Chang, J. Tsai, T. Li, and H. Liao, “LED backlight module by lightguide-diffusive component,” J. Disp. Technol. 8, 79–86 (2012).
    [CrossRef]
  6. Z. Qin, C. Ji, K. Wang, and S. Liu, “Analysis of light emitting diode array lighting system based on human vision: normal and abnormal uniformity condition,” Opt. Express 20, 23927–23943 (2012).
    [CrossRef]
  7. I. Moreno, M. Avendano-Alejo, and R. Tzonchev, “Designing light-emitting diode arrays for uniform near-field irradiance,” Appl. Opt. 45, 2265–2272 (2006).
    [CrossRef]
  8. W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
    [CrossRef]
  9. S. Swinkels, R. Muijs, E. Langendijk, and F. Vossen, “Effect of backlight segmentation on perceived image quality for HDR display,” Proceedings of IDW’06 (2006), pp. 1451–1454.
  10. Y. H. Lu, Y. K. Cheng, and C. H. Tien, “A localized pattern approach for high-dynamic-range display,” SID Symp. Dig. Technol. Papers 38, 449–452 (2007).
    [CrossRef]
  11. M. A. Moiseev, L. L. Doskolovich, E. V. Byzov, and S. V. Kravchenko, “Design of freeform LED optical elements for direct backlight systems,” Proc. SPIE 8410, 84100H (2011).
    [CrossRef]
  12. Y. Cheng, Y. Lu, C. Tien, and H. Shieh, “Design and evaluation of light spread function for area-adaptive LCD system,” J. Disp. Technol. 5, 66–71 (2009).
    [CrossRef]
  13. M. Unser, “Splines: a perfect fit for signal and image processing,” IEEE Signal Process. Mag. 16(6), 22–38 (1999).
    [CrossRef]

2012 (2)

2011 (1)

M. A. Moiseev, L. L. Doskolovich, E. V. Byzov, and S. V. Kravchenko, “Design of freeform LED optical elements for direct backlight systems,” Proc. SPIE 8410, 84100H (2011).
[CrossRef]

2009 (3)

Y. Cheng, Y. Lu, C. Tien, and H. Shieh, “Design and evaluation of light spread function for area-adaptive LCD system,” J. Disp. Technol. 5, 66–71 (2009).
[CrossRef]

W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
[CrossRef]

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

2008 (1)

C. Lai and C. Tsai, “Backlight power reduction and image contrast enhancement using adaptive dimming for global backlight applications,” IEEE Trans. Consum. Electron. 54, 669–674 (2008).
[CrossRef]

2007 (2)

H. Chen, J. Sung, T. Ha, and Y. Park, “Locally pixel-compensated backlight dimming for improving contrast on LED backlit LCDs,” SID Symp. Dig. Technol. Papers 38, 1339–1342 (2007).
[CrossRef]

Y. H. Lu, Y. K. Cheng, and C. H. Tien, “A localized pattern approach for high-dynamic-range display,” SID Symp. Dig. Technol. Papers 38, 449–452 (2007).
[CrossRef]

2006 (1)

2004 (1)

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

1999 (1)

M. Unser, “Splines: a perfect fit for signal and image processing,” IEEE Signal Process. Mag. 16(6), 22–38 (1999).
[CrossRef]

Avendano-Alejo, M.

Byzov, E. V.

M. A. Moiseev, L. L. Doskolovich, E. V. Byzov, and S. V. Kravchenko, “Design of freeform LED optical elements for direct backlight systems,” Proc. SPIE 8410, 84100H (2011).
[CrossRef]

Chang, R.

R. Chang, J. Tsai, T. Li, and H. Liao, “LED backlight module by lightguide-diffusive component,” J. Disp. Technol. 8, 79–86 (2012).
[CrossRef]

Chen, H.

H. Chen, J. Sung, T. Ha, and Y. Park, “Locally pixel-compensated backlight dimming for improving contrast on LED backlit LCDs,” SID Symp. Dig. Technol. Papers 38, 1339–1342 (2007).
[CrossRef]

Cheng, Y.

Y. Cheng, Y. Lu, C. Tien, and H. Shieh, “Design and evaluation of light spread function for area-adaptive LCD system,” J. Disp. Technol. 5, 66–71 (2009).
[CrossRef]

Cheng, Y. K.

Y. H. Lu, Y. K. Cheng, and C. H. Tien, “A localized pattern approach for high-dynamic-range display,” SID Symp. Dig. Technol. Papers 38, 449–452 (2007).
[CrossRef]

Cho, D.

W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
[CrossRef]

Cho, K.

W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
[CrossRef]

Chou, Q.-Y.

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

Doskolovich, L. L.

M. A. Moiseev, L. L. Doskolovich, E. V. Byzov, and S. V. Kravchenko, “Design of freeform LED optical elements for direct backlight systems,” Proc. SPIE 8410, 84100H (2011).
[CrossRef]

Ghosh, A.

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Ha, T.

H. Chen, J. Sung, T. Ha, and Y. Park, “Locally pixel-compensated backlight dimming for improving contrast on LED backlit LCDs,” SID Symp. Dig. Technol. Papers 38, 1339–1342 (2007).
[CrossRef]

Heidrich, W.

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Huang, W.

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

Jang, T.

W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
[CrossRef]

Ji, C.

Jin, Z.-L.

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

Kravchenko, S. V.

M. A. Moiseev, L. L. Doskolovich, E. V. Byzov, and S. V. Kravchenko, “Design of freeform LED optical elements for direct backlight systems,” Proc. SPIE 8410, 84100H (2011).
[CrossRef]

Lai, C.

C. Lai and C. Tsai, “Backlight power reduction and image contrast enhancement using adaptive dimming for global backlight applications,” IEEE Trans. Consum. Electron. 54, 669–674 (2008).
[CrossRef]

Langendijk, E.

S. Swinkels, R. Muijs, E. Langendijk, and F. Vossen, “Effect of backlight segmentation on perceived image quality for HDR display,” Proceedings of IDW’06 (2006), pp. 1451–1454.

Li, F.

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

Li, T.

R. Chang, J. Tsai, T. Li, and H. Liao, “LED backlight module by lightguide-diffusive component,” J. Disp. Technol. 8, 79–86 (2012).
[CrossRef]

Liao, H.

R. Chang, J. Tsai, T. Li, and H. Liao, “LED backlight module by lightguide-diffusive component,” J. Disp. Technol. 8, 79–86 (2012).
[CrossRef]

Liu, S.

Liu, Y.

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

Lu, Y.

Y. Cheng, Y. Lu, C. Tien, and H. Shieh, “Design and evaluation of light spread function for area-adaptive LCD system,” J. Disp. Technol. 5, 66–71 (2009).
[CrossRef]

Lu, Y. H.

Y. H. Lu, Y. K. Cheng, and C. H. Tien, “A localized pattern approach for high-dynamic-range display,” SID Symp. Dig. Technol. Papers 38, 449–452 (2007).
[CrossRef]

Ming, H.

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

Moiseev, M. A.

M. A. Moiseev, L. L. Doskolovich, E. V. Byzov, and S. V. Kravchenko, “Design of freeform LED optical elements for direct backlight systems,” Proc. SPIE 8410, 84100H (2011).
[CrossRef]

Moon, G.

W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
[CrossRef]

Moreno, I.

Muijs, R.

S. Swinkels, R. Muijs, E. Langendijk, and F. Vossen, “Effect of backlight segmentation on perceived image quality for HDR display,” Proceedings of IDW’06 (2006), pp. 1451–1454.

Oh, W.

W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
[CrossRef]

Park, Y.

H. Chen, J. Sung, T. Ha, and Y. Park, “Locally pixel-compensated backlight dimming for improving contrast on LED backlit LCDs,” SID Symp. Dig. Technol. Papers 38, 1339–1342 (2007).
[CrossRef]

Qin, Z.

Seetzen, H.

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Shieh, H.

Y. Cheng, Y. Lu, C. Tien, and H. Shieh, “Design and evaluation of light spread function for area-adaptive LCD system,” J. Disp. Technol. 5, 66–71 (2009).
[CrossRef]

Stuerzlinger, W.

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Sung, J.

H. Chen, J. Sung, T. Ha, and Y. Park, “Locally pixel-compensated backlight dimming for improving contrast on LED backlit LCDs,” SID Symp. Dig. Technol. Papers 38, 1339–1342 (2007).
[CrossRef]

Swinkels, S.

S. Swinkels, R. Muijs, E. Langendijk, and F. Vossen, “Effect of backlight segmentation on perceived image quality for HDR display,” Proceedings of IDW’06 (2006), pp. 1451–1454.

Tien, C.

Y. Cheng, Y. Lu, C. Tien, and H. Shieh, “Design and evaluation of light spread function for area-adaptive LCD system,” J. Disp. Technol. 5, 66–71 (2009).
[CrossRef]

Tien, C. H.

Y. H. Lu, Y. K. Cheng, and C. H. Tien, “A localized pattern approach for high-dynamic-range display,” SID Symp. Dig. Technol. Papers 38, 449–452 (2007).
[CrossRef]

Trentacoste, M.

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Tsai, C.

C. Lai and C. Tsai, “Backlight power reduction and image contrast enhancement using adaptive dimming for global backlight applications,” IEEE Trans. Consum. Electron. 54, 669–674 (2008).
[CrossRef]

Tsai, J.

R. Chang, J. Tsai, T. Li, and H. Liao, “LED backlight module by lightguide-diffusive component,” J. Disp. Technol. 8, 79–86 (2012).
[CrossRef]

Tzonchev, R.

Unser, M.

M. Unser, “Splines: a perfect fit for signal and image processing,” IEEE Signal Process. Mag. 16(6), 22–38 (1999).
[CrossRef]

Vorozcovs, A.

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Vossen, F.

S. Swinkels, R. Muijs, E. Langendijk, and F. Vossen, “Effect of backlight segmentation on perceived image quality for HDR display,” Proceedings of IDW’06 (2006), pp. 1451–1454.

Wang, K.

Ward, G.

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Whitehead, L.

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Yang, B.

W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
[CrossRef]

Zhong, Z.-G.

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

ACM Trans. Graph. (1)

H. Seetzen, W. Heidrich, W. Stuerzlinger, G. Ward, L. Whitehead, M. Trentacoste, A. Ghosh, and A. Vorozcovs, “High dynamic range display systems,” ACM Trans. Graph. 23, 760–768 (2004).
[CrossRef]

Appl. Opt. (1)

IEEE Signal Process. Mag. (1)

M. Unser, “Splines: a perfect fit for signal and image processing,” IEEE Signal Process. Mag. 16(6), 22–38 (1999).
[CrossRef]

IEEE Trans. Consum. Electron. (1)

C. Lai and C. Tsai, “Backlight power reduction and image contrast enhancement using adaptive dimming for global backlight applications,” IEEE Trans. Consum. Electron. 54, 669–674 (2008).
[CrossRef]

J. Disp. Technol. (3)

W. Oh, D. Cho, K. Cho, G. Moon, B. Yang, and T. Jang, “A novel two-dimensional adaptive dimming technique of X-Y channel drivers for LED backlight system in LCD TVs,” J. Disp. Technol. 5, 20–26 (2009).
[CrossRef]

R. Chang, J. Tsai, T. Li, and H. Liao, “LED backlight module by lightguide-diffusive component,” J. Disp. Technol. 8, 79–86 (2012).
[CrossRef]

Y. Cheng, Y. Lu, C. Tien, and H. Shieh, “Design and evaluation of light spread function for area-adaptive LCD system,” J. Disp. Technol. 5, 66–71 (2009).
[CrossRef]

Opt. Express (1)

Proc. SPIE (2)

W. Huang, Z.-L. Jin, Z.-G. Zhong, Y. Liu, H. Ming, Q.-Y. Chou, and F. Li, “A novel local dimming algorithm for RGB-LED backlight,” Proc. SPIE 7509, 750903 (2009).
[CrossRef]

M. A. Moiseev, L. L. Doskolovich, E. V. Byzov, and S. V. Kravchenko, “Design of freeform LED optical elements for direct backlight systems,” Proc. SPIE 8410, 84100H (2011).
[CrossRef]

SID Symp. Dig. Technol. Papers (2)

Y. H. Lu, Y. K. Cheng, and C. H. Tien, “A localized pattern approach for high-dynamic-range display,” SID Symp. Dig. Technol. Papers 38, 449–452 (2007).
[CrossRef]

H. Chen, J. Sung, T. Ha, and Y. Park, “Locally pixel-compensated backlight dimming for improving contrast on LED backlit LCDs,” SID Symp. Dig. Technol. Papers 38, 1339–1342 (2007).
[CrossRef]

Other (1)

S. Swinkels, R. Muijs, E. Langendijk, and F. Vossen, “Effect of backlight segmentation on perceived image quality for HDR display,” Proceedings of IDW’06 (2006), pp. 1451–1454.

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Figures (11)

Fig. 1.
Fig. 1.

1D PSFs: quadratic B-spline (solid) and PSF of a Lambertian emitter (dotted) with the same full width at half-maximum.

Fig. 2.
Fig. 2.

1D luminance of seven LEDs with a quadratic B-spline as PSF. A uniform luminance level (solid) was achieved as well as perfectly linear (dashed) and quadratic (dotted) gradients.

Fig. 3.
Fig. 3.

Schematic of a setup that creates PSFs on the screen. The PSFs have the shape of quadratic B-splines in the x and y directions. The walls between the LEDs were opaque to confine the light within the corresponding area on the screen. The filters consisted of a gray-scale pattern with spatially variable transmission to change the original PSF of the LEDs into the new shape.

Fig. 4.
Fig. 4.

Schematic side view of simulation setup. Through ray-tracing, the simulation determined the intensity pattern on the screen caused by a given luminance distribution of the source plane. E(x,y) is the pixelated light emission plane (LEP) of one unit spacing and I(x,y) is the pixelated intensity function of incident light on the screen at distance d. The width of I(x,y) is three unit spacings. Opaque baffles of height d/2 surround I(x,y).

Fig. 5.
Fig. 5.

Setup to verify simulation: 10cm×10cm LEP made with a uniform backlight with a diffuser and an absorptive filter.

Fig. 6.
Fig. 6.

Setup of reflective variable transmission filter, consisting of a stack of paper and diffuser films with holes. The more diffuse material at a given position, the lower the transmission.

Fig. 7.
Fig. 7.

Fifteen calibration filters. Filters were black with hole positions based on horizontal, vertical, and diagonal symmetry of the system.

Fig. 8.
Fig. 8.

Variation on the “uniform” screen of the backlight measured from normal angle. The line scan has a fractional RMS deviation of 0.6%. A cosine function was fitted to the data (solid) to determine a contrast modulation of 0.8%.

Fig. 9.
Fig. 9.

Data points extracted from line scans across the screen of the backlight, showing the linear gradient setting (circle) and the quadratic gradient setting (cross). The lines are fits using first (linear) and second (quadratic) order polynomials. The fractional RMS error between the measured line scans and the fits are 1.6% (linear) and 1.8% (quadratic).

Fig. 10.
Fig. 10.

Line scan demonstrating decrease of light level with increasing distance from the LED (dashed). The active LED is positioned at ‘0’. The solid line is plotted on a logarithmic scale, which is shown on the axis on the right-hand side. The linearity of these data suggested an exponential drop of the light level.

Fig. 11.
Fig. 11.

Based on measurements of the small backlight, the flux transfer from one LED module to the next was determined, and a larger display was simulated. The given scenario is that one LED at position 0 is switched on and the amount of flux which traveled to a distant module is shown in the graph. The triangle data points show the flux transfer for a backlight with opaque baffles; the crosses are data points for the same backlight with retro-reflective baffles; and the round data points show the simulation results for a backlight without baffles.

Equations (4)

Equations on this page are rendered with MathJax. Learn more.

I(x)=cos2(θ)(aa2+x2)2=cos4(θ).
for|x|12:f(x)=34x2for12<|x|32:f(x)=12(|x|32)2for|x|>32:f(x)=0.
f(x,y)=f(x)f(y).
F=(Δuni2+Δlin2+Δquad2)1/2.

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