Abstract

Presented here are experimental results of an extended depth-of-field (EDF) system using film to record the image. The EDF system used is an application of wave-front coding. A phase mask is placed in the aperture stop of the lens to code the image data; then digital signal processing is used to decode the image. Wave-front coding is based on linear systems theory, but film is not a linear medium. An extra step of linearization is then needed to apply the technique. Both nonlinear and linearized results are shown, as is a test image that demonstrates the success of the technique for nonlinear media.

© 2002 Optical Society of America

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References

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  1. E. R. Dowski, W. T. Cathey, “Extended depth of field through wave-front coding,” Appl. Opt. 34, 1859–1866 (1995).
    [CrossRef] [PubMed]
  2. S. Bradburn, W. T. Cathey, E. R. Dowski, “Realizations of focus invariance in optical-digital systems with wave-front coding,” Appl. Opt. 36, 9157–9166 (1997).
    [CrossRef]

1997

1995

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Figures (10)

Fig. 1
Fig. 1

Exposure curve for Kodak T-Max 100 film, developed in Kodak T-Max developer for 7 min at 72 F.

Fig. 2
Fig. 2

Nonlinear PSFs recorded on film (inverted for clarity); each successive PSF is at double the exposure of the previous, with histograms for each image.

Fig. 3
Fig. 3

Nonlinear MTFs. The highest MTF on the graph corresponds to the least-exposed PSF, on down.

Fig. 4
Fig. 4

Nonlinear PSFs after filtering.

Fig. 5
Fig. 5

PSFs recorded on film (inverted for clarity), after linearization, with histograms for each image.

Fig. 6
Fig. 6

Linearized MTFs.

Fig. 7
Fig. 7

Linearized PSFs after filtering.

Fig. 8
Fig. 8

Standard system dollar bill image.

Fig. 9
Fig. 9

CPM system dollar bill image, after linearization.

Fig. 10
Fig. 10

CPM system dollar bill image, after linearization and filtering.

Equations (1)

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Fν, ξ=Wν, ξH*ν, ξHν, ξH*ν, ξ+σ,

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