Abstract

A new and simple method has been developed for fabrication of multilevel halftone screens that have proved useful for generation of equidensity contours by means of coherent optical filtering. Up to ten contours of constant brightness have been generated on a picture by coherent optical filtering of a single halftone copy of that picture. The possible application of this method to optical analog-to-digital conversion using a single halftone photograph is discussed.

© 1976 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. H. Kato, J. W. Goodman, Opt. Commun. 8, 378 (1973).
  2. H. Kato, J. W. Goodman, J. Opt. Soc. Am. 63, 1306A (1973).
  3. A. A. Sawchuk, S. R. Dashiell, in Proc. IEEE Int. Computing Conf. (April1975), p. 173; also Opt. Commun. 15, 66 (1975).
  4. T. C. Strand, Opt. Commun. 15, 60 (1975).
  5. S. R. Dashiell, U. Southern California; private communication.
  6. A. Lohmann, T. C. Strand, “Analog-to-Digital Conversion by Optical Means,” in Proceedings of the 1975 Electro-Optical Systems Design Conference, Anaheim, California.
  7. The exact levels Tn(n = 1,2,…,7) required depend on the photographic gamma of the input transparency, assuming that it is the original exposure distribution of this transparency that is to be digitized.
  8. Strictly speaking, no hard-clipping detector is required for the seventh-order image, since the output emerges already in binary form.
  9. Hua-Kuang Liu, Joseph W. Goodman, Nouv, Rev. Optique, Sept. (1976).

1976 (1)

Hua-Kuang Liu, Joseph W. Goodman, Nouv, Rev. Optique, Sept. (1976).

1975 (1)

T. C. Strand, Opt. Commun. 15, 60 (1975).

1973 (2)

H. Kato, J. W. Goodman, Opt. Commun. 8, 378 (1973).

H. Kato, J. W. Goodman, J. Opt. Soc. Am. 63, 1306A (1973).

Dashiell, S. R.

A. A. Sawchuk, S. R. Dashiell, in Proc. IEEE Int. Computing Conf. (April1975), p. 173; also Opt. Commun. 15, 66 (1975).

S. R. Dashiell, U. Southern California; private communication.

Goodman, J. W.

H. Kato, J. W. Goodman, Opt. Commun. 8, 378 (1973).

H. Kato, J. W. Goodman, J. Opt. Soc. Am. 63, 1306A (1973).

Goodman, Joseph W.

Hua-Kuang Liu, Joseph W. Goodman, Nouv, Rev. Optique, Sept. (1976).

Kato, H.

H. Kato, J. W. Goodman, Opt. Commun. 8, 378 (1973).

H. Kato, J. W. Goodman, J. Opt. Soc. Am. 63, 1306A (1973).

Liu, Hua-Kuang

Hua-Kuang Liu, Joseph W. Goodman, Nouv, Rev. Optique, Sept. (1976).

Lohmann, A.

A. Lohmann, T. C. Strand, “Analog-to-Digital Conversion by Optical Means,” in Proceedings of the 1975 Electro-Optical Systems Design Conference, Anaheim, California.

Sawchuk, A. A.

A. A. Sawchuk, S. R. Dashiell, in Proc. IEEE Int. Computing Conf. (April1975), p. 173; also Opt. Commun. 15, 66 (1975).

Strand, T. C.

T. C. Strand, Opt. Commun. 15, 60 (1975).

A. Lohmann, T. C. Strand, “Analog-to-Digital Conversion by Optical Means,” in Proceedings of the 1975 Electro-Optical Systems Design Conference, Anaheim, California.

J. Opt. Soc. Am. (1)

H. Kato, J. W. Goodman, J. Opt. Soc. Am. 63, 1306A (1973).

Nouv, Rev. Optique (1)

Hua-Kuang Liu, Joseph W. Goodman, Nouv, Rev. Optique, Sept. (1976).

Opt. Commun. (2)

H. Kato, J. W. Goodman, Opt. Commun. 8, 378 (1973).

T. C. Strand, Opt. Commun. 15, 60 (1975).

Other (5)

S. R. Dashiell, U. Southern California; private communication.

A. Lohmann, T. C. Strand, “Analog-to-Digital Conversion by Optical Means,” in Proceedings of the 1975 Electro-Optical Systems Design Conference, Anaheim, California.

The exact levels Tn(n = 1,2,…,7) required depend on the photographic gamma of the input transparency, assuming that it is the original exposure distribution of this transparency that is to be digitized.

Strictly speaking, no hard-clipping detector is required for the seventh-order image, since the output emerges already in binary form.

A. A. Sawchuk, S. R. Dashiell, in Proc. IEEE Int. Computing Conf. (April1975), p. 173; also Opt. Commun. 15, 66 (1975).

Cited By

OSA participates in Crossref's Cited-By Linking service. Citing articles from OSA journals and other participating publishers are listed here.

Alert me when this article is cited.


Figures (7)

Fig. 1
Fig. 1

A three level halftone screen produced by one translation of a Ronchi ruling mask and two exposures. (a) Ronchi ruling transmittance function with no translation. The period is a. A first exposure is made at this position. (b) Ronchi ruling transmittance with a translation of the film plate of Δx = a/3. A second exposure is made at this position. (c) Density function of the resulted halftone screen due to the exposures through the Ronchi ruling.

Fig. 2
Fig. 2

Portions of two different halftone screens enlarged.

Fig. 3
Fig. 3

A coherent optical data processing system.

Fig. 4
Fig. 4

The normalized outputs of the first through the fifth diffraction order.

Fig. 5
Fig. 5

The original photograph, its halftone photograph A, and the image outputs of the various diffraction orders.

Fig. 6
Fig. 6

Halftone photograph B and the image outputs of its zero through seventh diffraction order.

Fig. 7
Fig. 7

Illustration of how three-bit outputs, I01, I03, and I07, are generated by a single halftone photograph with eight different bar widths. These widths are b/a = 0.5 + n/14 for n = 0,1,2,3,4,5,6, and 7. Ith is the detection threshold.

Equations (10)

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

T ( x ) = 1 ,             0 < x a / N = 0 ,             a / N < x a ,
E ( x ) = p τ i ,             ( i - 1 ) a / N x < i a / N ,
D ( x ) = γ log ( E ( x ) - D 0 ,
D ( x ) = D ( x + a ) ,             and D ( x ) = D 1 ,             0 < x a / 6 and a / 2 < x 2 a / 3 , = D 2 ,             a / 6 < x a / 2 ; = D 0 ,             2 a / 3 < x a .
E ( x , y ) = p τ 10 [ - D ( x ) - D p ( x , y ) ] ,
T ( x , y ) = 1 ,             E ( x , y ) < E t , = 0 ,             E ( x , y ) E t .
I n ( b a ) = ( 1 n π sin n π b a ) 2 ,
I ¯ n ( b a ) = n 2 π 2 I n ( b a ) = sin 2 n π b a ,
I 0 = ( 1 - b a ) 2 .
T ( x ) = { 0 0 < x a / 2 T n a 2 + ( n - 1 ) a 14 < x a 2 + n a 14

Metrics