Abstract

Continuous-tone images produced by mechanically scanned analog modulated laser beams are susceptible to image artifacts in the form of spatially periodic density variations due to machine errors in film transport velocity, raster scan-line placement, and scan-line intensity. The human eye is particularly sensitive to periodic patterns and, in ideal conditions, can detect peak-to-peak density variations as small as ~0.005 for spatial frequencies around 2–5 cycles/deg. The stringent requirements that this implies for the scanner hardware are derived. Particular attention is paid to the rotating polygon-type scanner, since this device currently provides the best combination of speed, image quality, and cost.

© 1986 Optical Society of America

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References

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  1. F. Bestenreiner, U. Greis, J. Helmberger, K. Stadler, “Visibility and Correction of Periodic Interference Structures in Line-by-Line Recorded Images,” J. Appl. Photogr. Eng. 2, No. 2, 86 (1976).
  2. D. H. Kelly, “Visual Contrast Sensitivity,” Opt. Acta 24, No. 2, 107 (1977).
    [CrossRef]
  3. F. W. Campbell, D. G. Green, “Optical and Retinal Factors Affecting Visual Resolution,” J. Physiol. 181, 576 (1965).
    [PubMed]

1977 (1)

D. H. Kelly, “Visual Contrast Sensitivity,” Opt. Acta 24, No. 2, 107 (1977).
[CrossRef]

1976 (1)

F. Bestenreiner, U. Greis, J. Helmberger, K. Stadler, “Visibility and Correction of Periodic Interference Structures in Line-by-Line Recorded Images,” J. Appl. Photogr. Eng. 2, No. 2, 86 (1976).

1965 (1)

F. W. Campbell, D. G. Green, “Optical and Retinal Factors Affecting Visual Resolution,” J. Physiol. 181, 576 (1965).
[PubMed]

Bestenreiner, F.

F. Bestenreiner, U. Greis, J. Helmberger, K. Stadler, “Visibility and Correction of Periodic Interference Structures in Line-by-Line Recorded Images,” J. Appl. Photogr. Eng. 2, No. 2, 86 (1976).

Campbell, F. W.

F. W. Campbell, D. G. Green, “Optical and Retinal Factors Affecting Visual Resolution,” J. Physiol. 181, 576 (1965).
[PubMed]

Green, D. G.

F. W. Campbell, D. G. Green, “Optical and Retinal Factors Affecting Visual Resolution,” J. Physiol. 181, 576 (1965).
[PubMed]

Greis, U.

F. Bestenreiner, U. Greis, J. Helmberger, K. Stadler, “Visibility and Correction of Periodic Interference Structures in Line-by-Line Recorded Images,” J. Appl. Photogr. Eng. 2, No. 2, 86 (1976).

Helmberger, J.

F. Bestenreiner, U. Greis, J. Helmberger, K. Stadler, “Visibility and Correction of Periodic Interference Structures in Line-by-Line Recorded Images,” J. Appl. Photogr. Eng. 2, No. 2, 86 (1976).

Kelly, D. H.

D. H. Kelly, “Visual Contrast Sensitivity,” Opt. Acta 24, No. 2, 107 (1977).
[CrossRef]

Stadler, K.

F. Bestenreiner, U. Greis, J. Helmberger, K. Stadler, “Visibility and Correction of Periodic Interference Structures in Line-by-Line Recorded Images,” J. Appl. Photogr. Eng. 2, No. 2, 86 (1976).

J. Appl. Photogr. Eng. (1)

F. Bestenreiner, U. Greis, J. Helmberger, K. Stadler, “Visibility and Correction of Periodic Interference Structures in Line-by-Line Recorded Images,” J. Appl. Photogr. Eng. 2, No. 2, 86 (1976).

J. Physiol. (1)

F. W. Campbell, D. G. Green, “Optical and Retinal Factors Affecting Visual Resolution,” J. Physiol. 181, 576 (1965).
[PubMed]

Opt. Acta (1)

D. H. Kelly, “Visual Contrast Sensitivity,” Opt. Acta 24, No. 2, 107 (1977).
[CrossRef]

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Figures (4)

Fig. 1
Fig. 1

Contrast sensitivity of the eye. Threshold peak-to-peak density vs spatial frequency for viewing distance of 300 mm: open circles, data from Fig. 2 of Ref. 2; short curve, fit to data from Fig. 9 of Ref. 3; long curve, overall fit to data.

Fig. 2
Fig. 2

General form of flatbed raster-type laser scanner.

Fig. 3
Fig. 3

(a) Scan-line intensity profiles (top plot) and film-transport velocity variations. (b) Scan-line intensity profiles and line-position errors. (c) Scan-line intensity profiles and beam intensity errors.

Fig. 4
Fig. 4

Spectrum of density variations for case in which every twelfth scan line is out of position by 5% of the nominal line spacing. Viewing distance is assumed to be 300 mm.

Equations (16)

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Δ D P - P = [ 2 / ln ( 10 ) ] Δ L / L 0 ,
Δ D P - P = 1.94 × 10 - 3 exp ( 0.587 f ) ,
Δ D P - P = exp { a 1 + a 2 f + a 3 ln ( f ) } + a 4 [ ln ( f ) ] 2 } .
Δ E / E 0 = Δ v / v 0 ,
D = D 0 + γ log ( E / E 0 ) ,
Δ D = [ γ / ln ( 10 ) ] Δ v / v 0 .
Δ x n = ( Δ x P - P / 2 ) sin ( 2 π n / M ) ,
d Δ x n / d n = ( 2 π / M ) ( Δ x P - P / 2 ) cos ( 2 π n / M ) .
Δ D P - P = [ γ / ln ( 10 ) ] ( 2 π / M ) Δ x P - P / p ,
x n = x n 0 + Δ x n = n p + ( Δ x P - P / 2 ) sin ( 2 π n / M ) ,
E ( x ) = P 0 ( 2 / π ) 1 / 2 ( ω v s ) - 1 n exp [ - 2 ( x - x n ) 2 / ω 2 ] ,
E ( x ) = k m F ( k m ) exp ( i k m x ) , k m = 2 π m / ( N p ) , m = - 2 , - 1 , 0 , 1 , 2 , , F ( k m ) = ( N p ) - 1 0 N p E ( x ) exp ( - i k m x ) d x .
F ( k m ) = ( N p ) - 1 ( P 0 / v s ) exp ( - k m 2 ω 2 / 8 ) n = 0 N - 1 exp ( - i k m x n ) .
E ( x ) = 2 k m F ( k m ) cos ( k m + θ m ) ,
Δ D P - P 0 ( n f 0 ) = 4 [ γ / ln ( 10 ) ] exp [ - ( π 2 / 2 ) n 2 ( ω / p ) 2 ] .
Δ D P - P M ( n f M ) = 4 M - 1 [ γ / ln ( 10 ) ] exp [ - ( π 2 / 2 ) ( n / M ) 2 ( ω / p ) 2 ] × | m = 0 M - 1 exp ( 2 π i n f M x m ) | .

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