study of image quality of superimposed projection using multiple projectors takayuki okatani,...

Study of Image Quality of Study of Image Quality of Superimposed ProjectionSuperimposed ProjectionUsing Multiple ProjectorsUsing Multiple Projectors

Takayuki OkataniTakayuki Okatani, Member, IEEE, Member, IEEE, Mikio Wada, and, Mikio Wada, andKoichiro DeguchiKoichiro Deguchi, Member, IEEE, Member, IEEE

指導教授 張元翔指導教授 張元翔 報告人員 陳昱辰報告人員 陳昱辰

INTRODUCTIONINTRODUCTION

‧a high-resolution image can be generated by superimposing multiple lower-resolution images projected by different projectors.

• analyze the quality of the images realized by this method and show its several fundamental properties.

INTRODUCTIONINTRODUCTION

‧A key problem in superimposed projection is the computation of the images fed to the component projectors in order to realize a desired image.

‧we mainly consider the box PSF having the same size as a pixel, which is considered to be a good approximation in the case of a DLP projector.

MULTIPROJECTOR SUPER-MULTIPROJECTOR SUPER-RESOLUTIONRESOLUTION

• Model of the Image Formation

MULTIPROJECTOR SUPER-MULTIPROJECTOR SUPER-RESOLUTIONRESOLUTION

• Computing the Projector Images

‧This is subject to the lower and upper bounds of the projector pixel brightness

DEPENDENCY OF REALIZATION DEPENDENCY OF REALIZATION ACCURACY ON IMAGE ACCURACY ON IMAGE

STRUCTURESSTRUCTURES

• Analyzing Toy Problems

‧Let us consider the case of 1-D images. We assume the prefilter p and the reconstruction filter r to be box functions whose widths are equivalent to the pixel size of the target image and the projector image,respectively.

Fig.1Fig.1

A single dark pixel

Fig.2Fig.2

A single bright pixel

Fig3.4.5Fig3.4.5

•

DEPENDENCY OF REALIZATION DEPENDENCY OF REALIZATION ACCURACY ON IMAGE ACCURACY ON IMAGE

STRUCTURESSTRUCTURES‧Experimental Results

‧The accuracy of image realization by superimposed

projection is affected by the target image itself. A typical example is that black-on-white text images tend to be realized more accurately than white-on-black text

images.

TRADEOFF BETWEEN TRADEOFF BETWEEN REALIZATION ACCURACY ANDREALIZATION ACCURACY AND

IMAGE BRIGHTNESSIMAGE BRIGHTNESS

‧Degrees of Freedom in the Projector Image Optimization

Maximum brightness is considered to be an important factor in projection-based-display.

the target pixel is less bright, none of these projector pixels may reach the upper bound of the pixel brightness.

Fig7.8Fig7.8

• a = 1 a = 5

Fig6.9Fig6.9

TRADEOFF BETWEEN TRADEOFF BETWEEN REALIZATION ACCURACY ANDREALIZATION ACCURACY AND

IMAGE BRIGHTNESSIMAGE BRIGHTNESS

• Experimental Results

There is a general tendency that the realization accuracy monotonically deteriorates as the brightness of the target image increases.

DEMONSTRATION BY A REAL DEMONSTRATION BY A REAL SYSTEMSYSTEM

• Experimental System

DEMONSTRATION BY A REAL DEMONSTRATION BY A REAL SYSTEMSYSTEM

‧Experimental methods

For the geometric calibration, we used the phase-shift method,which is widely used in range finders, to establish the pixel-to-pixel correspondences between the images of the projector and the calibration camera.

Using a sinusoidal brightness pattern for projection, weestimates the phase of the pattern from the brightness changes at each camera pixel when shifting the phase of the sinusoidal pattern.

Fig11.12Fig11.12

DEMONSTRATION BY A REAL DEMONSTRATION BY A REAL SYSTEMSYSTEM

‧Experimental Results

These results verify our theoretical results with respect to the image quality of superimposed projection; they hold in the case of real systems and images.

SUMMARY AND DISCUSSIONSSUMMARY AND DISCUSSIONS

• the realization accuracy depends on the structure of the target image to be realized

• The method of (multi) projector superimposed projection is itself a novel imaging technology and could have many potential applications not limited to ordinary image projection.