## Crosstalk reduction in auto-stereoscopic projection 3D display system |

Optics Express, Vol. 20, Issue 18, pp. 19757-19768 (2012)

http://dx.doi.org/10.1364/OE.20.019757

Acrobat PDF (2063 KB)

### Abstract

In auto-stereoscopic multi-views 3D display systems, the crosstalk and low resolution become problems for taking a clear depth image with the sufficient motion parallax. To solve these problems, we propose the projection-type auto-stereoscopic multi-view 3D display system, in which the hybrid optical system with the lenticular-parallax barrier and multi projectors. Condensing width of the projected unit-pixel image within the lenslet by hybrid optics is the core concept in this proposal. As the result, the point crosstalk is improved 53% and resolution is increased up to 5 times.

© 2012 OSA

## Introduction

1. T. Okoshi, “Three-dimensional displays,” Proc. IEEE **68**(5), 548–564 (1980). [CrossRef]

15. W.-X. Zhao, Q.-H. Wang, A.-H. Wang, and D.-H. Li, “Autostereoscopic display based on two-layer lenticular lenses,” Opt. Lett. **35**(24), 4127–4129 (2010). [CrossRef] [PubMed]

1. T. Okoshi, “Three-dimensional displays,” Proc. IEEE **68**(5), 548–564 (1980). [CrossRef]

9. H. Liao, M. Iwahara, N. Hata, and T. Dohi, “High quality integral videography by using a multi-projector,” Opt. Express **12**(6), 1067–1076 (2004). [CrossRef]

15. W.-X. Zhao, Q.-H. Wang, A.-H. Wang, and D.-H. Li, “Autostereoscopic display based on two-layer lenticular lenses,” Opt. Lett. **35**(24), 4127–4129 (2010). [CrossRef] [PubMed]

12. Y. Kusakabe, M. Kanazawa, Y. Nojiri, M. Furuya, and M. Yoshimura, “A high dynamic range and high resolution projector with dual modulation,” Proc. SPIE **7241**, 72410Q, 72410Q-11 (2009). [CrossRef]

15. W.-X. Zhao, Q.-H. Wang, A.-H. Wang, and D.-H. Li, “Autostereoscopic display based on two-layer lenticular lenses,” Opt. Lett. **35**(24), 4127–4129 (2010). [CrossRef] [PubMed]

## Preliminary Considerations

*x*<0.5; their shapes are unit-box. The Fig. 2 show the convolution calculated by Eq. (1), Fig. 2(a) shows the result for identical shapes h(x) = f(x) and Fig. 2(b) shows the case h(x) narrower than f(x), h(x) = f(0.1 x). As shown in Fig. 2(a) and (b), if the pixel is narrower, the result changes from a triangle to a rectangle.

*P*presents the pixel projected on the screen without lenticular lens sheet and adjusted to the pitch of lenslet (

_{1}*P*) according to the projected distance

*S*.

_{o}*P*presents the reduced width of

_{2}*P*. The width of pixel is strongly connected with the optical power of the lenslet. The origin of the coordinates is located at the center of the observer.

_{1}*G*represents the position of the viewpoint. Number

_{j}*j*represents the number of viewpoints. Number

*j*is the total number (

_{max}*N*) of designed viewpoints. Base Distance (BD) represents the interval between the centers of adjacent viewpoints. As such,

*d*represents the distance between the parallax barrier and the screen;

*A*represents the aperture of parallax barrier;

*B*indicates the width of the barrier;

*S*represents the distance from the of parallax barrier to the observing plane. From the given conditions,

*P*and BD, the values of

_{1}, S*d, A*and

*B*can be defined as follows.

*h*represents the collective number of views in the horizontal direction. The maximum value of

*h*is defined the permitted horizontal resolution of each view image. And

*m*represents the number of point light sources. The number

*m*ranges from 1 to

*k*. It is composed of a bundle of rays with a uniform density.

*P*is the centric coordinates for the point light sources within the pixel image on the diffusing sheet;

_{h,j,m}*X*indicates

_{h,j,m}*x*coordinates of the rays reached the horizontal axis at the observing plane;

*A*represents the centric coordinates of the aperture of the parallax barrier plate which corresponds to the

_{h}*h*-th collective number;

*E*indicates the light intensity at

_{h,j,m}*X*. The light intensity decreases in inverse proportion to the squared cosine of divergence angle and the distance from

_{h,j,m}*P*to

_{h,j,m}*X*. The viewing zone is formed as follows. The light bundle radiated from the

_{h,j,m}*m*-th point light source within the

*j*-th pixel passes the

*A*-th aperture of the parallax barrier at

_{h}*X*with the light intensity

_{h,j,m }*E*The range of

_{h,j,m}.*X*is confined to the defined, the horizontal viewing range of observer,

_{h,j,m}*x*; the accumulated value for this, ∑

_{min,max}*E*is defined as the light intensity distribution of the viewing zone. Equation (5) is the mathematical definition for the light intensity distribution of the viewing zone of light sources

_{h,j,m}*P*or

_{1}*P*.

_{2}*L*is given initial light intensity of point light source.

*C.*section /

*B.D*width’. This is referred to as the optimal viewing zone ratio. When this ratio is higher, the observer can view the wider clear image within the viewing zone.

*I*is the distance between the centers of the

*P*and

_{2}*ID*is the outermost interval between the centers of projection lens. The relation between them can be defined as the Eq. (7). In Eq. (7),

*n*and

_{d}*n*represent the refractive index of lenslet and air, and

_{m}*t*represents the thickness of lenticular lens sheet, and

*P*represents the pitch of lenslet. The layout corresponding to Eq. (7) is shown in Fig. 3 . The supposed maximum number of projectors is 1, 3 and 5.

## Experimental Result

*P*and

_{1}*P*.

_{2}*P*on the screen. Figure 4(a) shows the cross section of lenticular lens used in the experiment. Figure 4(c) shows the decreased image of the light source

_{1}*P*width formed through the lenslet.

_{2}*P*and

_{1}*P*, the following experiment was implemented: The measurement system was equipped with the 5-inch and the 42-inch screens. The 5-inch system was used for the measurement of image properties of the light source width, and the 42-inch system was used for the verification of reduced crosstalk. The constraint conditions applied in the experiment are the horizontal projection distance

_{2}*S*, the observing distance

_{o}*S = 1,100 mm*, and the interval between the viewpoints, BD

*= 15 mm.*The viewing-zone forming optical system is located away from the

*P*and the

_{1}*P*light source surfaces by the distance,

_{2}*d*= 74.5 mm, and has the properties with the aperture width

*A = 0.95 mm*and barrier width

*B = 3.80 mm.*

*x*-axis (from −50 mm to + 50 mm) from the center of the 5-inch screen, the brightness depending on the position of detector was measured. Additionally, the viewing zone distribution and crosstalk for the same viewpoint image from the light sources

*P*and

_{1}*P*are compared with each other. The verification of the crosstalk improvement by the reduced light source is implemented by use of the 42-inch system. The layout of the 42-inch system is the same as that for 5-inch system. The Fig. 5 represents the optical properties of each image penetrating through the apertures of the optical system and the 5-inch system comprised for the analysis of crosstalk. The viewpoint image projected from the projector consists of five images. The measurement distance and observing position is applied similarly for two cases (Fig. 5(a), (b)). The area of the effective light source

_{2}*P*is the reduced effective pixel. This implies that the light beams with the uniform density radiated from the light source

_{2}*P*contribute mainly near the center of the aperture of the optical system. Accordingly, the viewing zone from the light source

_{2}*P*becomes narrower and clearer than that from the light source

_{2}*P*, in case that the pitch of lenslet is used for the light source. In the highlighted magnified section in Fig. 5(a), (b), it can be checked that

_{1}*P*is narrower than the

_{2}*P*.

_{1}*P*light source. The

_{1}*x*-axis represents the measurement range of the detector, and the

*y*-axis represents the light intensity on the viewpoint. An arbitrary unit (AU) is used in the graph. The distance between the centers of viewpoints is 15 mm, which corresponds to the designed value. The viewing zone of the perpendicular parallax barrier has the triangular shape and represents the integrated brightness distribution. The brightness distribution in the lower part of graph is distorted by noise from the detector or by the ambient-light.

*P*, the minimum PC area is expanded. Accordingly, the viewpoint image by the light source

_{1}*P*has the low crosstalk within the viewing zone, which means a clearer image for the observer.

_{2}*P*. The minimum PC section for the light source

_{1}*P*is expanded. The Fig. 10 represents the light sources

_{2}*P*and

_{1}*P*in the 42-inch system measured at the observer position. The viewpoint image with

_{2}*P*has the lower crosstalk than that with

_{2}*P*.

_{1}*P*, the BD width is 15mm. Also, the low PC (PC<30%) is observed within 3mm. The optimal viewing zone ratio is 0.2. After the reduction, in case of the light source

_{1}*P*, the minimum PC range is 11mm. The optimal viewing zone ratio is 0.73. Therefore, the PC is improved by

_{2}*53%*. The maximum number of projectors available is 5, and the resolution of viewpoint image can be increased by five times. The Fig. 11 represents measured position between the centers of projection lens for each projector, when the number of projectors is 1, 3 and 5. When

*I*= 1/2, 1/3, and 2/5, the positions of the light sources

*P*are 0 mm, 0.34 mm, and 0.41 mm from the center of lenslet, respectively. The outermost interval

_{2}*ID*between the centers of projection lenses of projectors corresponds to 0mm, 389.95mm and 469.45mm, respectively, from Eq. (7).

## Discussion

## Conclusion

*N*, the resolution of viewpoint image increases by

_{views}*N*times. As a proposal for the application of this research, this system can expect to be applicable to the clear stereovision screen with a size of 42 inches or larger.

_{views}## Acknowledgment

## References and links

1. | T. Okoshi, “Three-dimensional displays,” Proc. IEEE |

2. | N. A. Dodgson, “Autostereoscopic 3D displays,” Computer |

3. | J.-Y. Son, V. V. Saveljev, J.-S. Kim, K.-D. Kwack, and S.-K. Kim, “Multiview image acquisition and display,” J. Display Tech. |

4. | J.-Y. Son, “Autostereoscopic imaging system based on special optical plates,” in |

5. | T. Peterka, R. L. Kooima, D. J. Sandin, A. Johnson, J. Leigh, and T. A. DeFanti, “Advances in the Dynallax solid-state dynamic parallax barrier autostereoscopic visualization display system,” IEEE Trans. Vis. Comput. Graph. |

6. | J.-Y. Son, V. V. Saveljev, Y.-J. Choi, J.-E. Bahn, and H.-H. Choi, “Parameters for designing autostereoscopic imaging systems based on lenticular, parallax barrier and IP plates,” Opt. Eng. |

7. | Y. Takaki, O. Yokoyama, and G. Hamagishi, “Flat-panel display with slanted pixel arrangement for 16-view display,” Proc. SPIE |

8. | T. Okoshi, “Optimum Design and Depth Resolution of Lens-Sheet and Projection- type Three dimensional Displays,” Appl. Opt. |

9. | H. Liao, M. Iwahara, N. Hata, and T. Dohi, “High quality integral videography by using a multi-projector,” Opt. Express |

10. | T. Okoshi, |

11. | T. Nagoya, T. Kozakai, T. Suzuki, M. Furuya, and K. Iwase, “The D-ILA device for the world’s highest definition (8K4K) projection systems,” Proc. IDW’08, 203–206 (2008). |

12. | Y. Kusakabe, M. Kanazawa, Y. Nojiri, M. Furuya, and M. Yoshimura, “A high dynamic range and high resolution projector with dual modulation,” Proc. SPIE |

13. | Y.-H. Tao, Q.-H. Wang, J. Gu, W.-X. Zhao, and D.-H. Li, “Autostereoscopic three-dimensional projector based on two parallax barriers,” Opt. Lett. |

14. | C.-H. Lee, G.-W. Seo, J.-H. Lee, T.-H. Han, and J.-G. Park, “Auto-stereoscopic 3D displays with reduced crosstalk,” Opt. Express |

15. | W.-X. Zhao, Q.-H. Wang, A.-H. Wang, and D.-H. Li, “Autostereoscopic display based on two-layer lenticular lenses,” Opt. Lett. |

**OCIS Codes**

(110.6880) Imaging systems : Three-dimensional image acquisition

(230.0230) Optical devices : Optical devices

(350.0350) Other areas of optics : Other areas of optics

**ToC Category:**

Imaging Systems

**History**

Original Manuscript: May 1, 2012

Revised Manuscript: July 17, 2012

Manuscript Accepted: July 30, 2012

Published: August 14, 2012

**Citation**

Kwang-Hoon Lee, Youngsik Park, Hyoung Lee, Seon Kyu Yoon, and Sung-Kyu Kim, "Crosstalk reduction in auto-stereoscopic projection 3D display system," Opt. Express **20**, 19757-19768 (2012)

http://www.opticsinfobase.org/oe/abstract.cfm?URI=oe-20-18-19757

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### References

- T. Okoshi, “Three-dimensional displays,” Proc. IEEE68(5), 548–564 (1980). [CrossRef]
- N. A. Dodgson, “Autostereoscopic 3D displays,” Computer38(8), 31–36 (2005). [CrossRef]
- J.-Y. Son, V. V. Saveljev, J.-S. Kim, K.-D. Kwack, and S.-K. Kim, “Multiview image acquisition and display,” J. Display Tech. 2(4), 359–363 (2006).
- J.-Y. Son, “Autostereoscopic imaging system based on special optical plates,” in Three-Dimensional Television, Video, and Display Technology B. Javidi and F. Okano, ed.(Springer, New York, 2002).
- T. Peterka, R. L. Kooima, D. J. Sandin, A. Johnson, J. Leigh, and T. A. DeFanti, “Advances in the Dynallax solid-state dynamic parallax barrier autostereoscopic visualization display system,” IEEE Trans. Vis. Comput. Graph.14(3), 487–499 (2008). [CrossRef] [PubMed]
- J.-Y. Son, V. V. Saveljev, Y.-J. Choi, J.-E. Bahn, and H.-H. Choi, “Parameters for designing autostereoscopic imaging systems based on lenticular, parallax barrier and IP plates,” Opt. Eng.42, 3326–3333 (2003).
- Y. Takaki, O. Yokoyama, and G. Hamagishi, “Flat-panel display with slanted pixel arrangement for 16-view display,” Proc. SPIE7237, 08–1–8 (2009).
- T. Okoshi, “Optimum Design and Depth Resolution of Lens-Sheet and Projection- type Three dimensional Displays,” Appl. Opt.10(10), 2284–2291 (1971).
- H. Liao, M. Iwahara, N. Hata, and T. Dohi, “High quality integral videography by using a multi-projector,” Opt. Express 12(6), 1067–1076 (2004). [CrossRef]
- T. Okoshi, 3 Dimensional Imaging Techniques (New York: Academic, 1976), ch. 2, 8–42.
- T. Nagoya, T. Kozakai, T. Suzuki, M. Furuya, and K. Iwase, “The D-ILA device for the world’s highest definition (8K4K) projection systems,” Proc. IDW’08, 203–206 (2008).
- Y. Kusakabe, M. Kanazawa, Y. Nojiri, M. Furuya, and M. Yoshimura, “A high dynamic range and high resolution projector with dual modulation,” Proc. SPIE7241, 72410Q, 72410Q-11 (2009). [CrossRef]
- Y.-H. Tao, Q.-H. Wang, J. Gu, W.-X. Zhao, and D.-H. Li, “Autostereoscopic three-dimensional projector based on two parallax barriers,” Opt. Lett.34(20), 3220–3222 (2009). [CrossRef] [PubMed]
- C.-H. Lee, G.-W. Seo, J.-H. Lee, T.-H. Han, and J.-G. Park, “Auto-stereoscopic 3D displays with reduced crosstalk,” Opt. Express19(24), 24762–24774 (2011). [CrossRef] [PubMed]
- W.-X. Zhao, Q.-H. Wang, A.-H. Wang, and D.-H. Li, “Autostereoscopic display based on two-layer lenticular lenses,” Opt. Lett.35(24), 4127–4129 (2010). [CrossRef] [PubMed]

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