Abstract

A photoelectric scanning instrument is described which gives granularity values in terms that can be converted into the graininess values that would be obtained by an observer viewing a magnified image of the sample under standard conditions. The procedure is to determine the critical scanning aperture that results in a signal corresponding to the threshold-gradient sensitivity of the eye for the density of the sample. The techniques for making two types of routine graininess measurements are described in detail. Class I measurements give the graininess of samples at a density of 0.8. Class II measurements give granularity numbers that indicate the relative graininess to be expected of matched prints made from the negatives.

© 1957 Optical Society of America

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References

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  1. L. A. Jones and G. C. Higgins, J. Opt. Soc. Am. 35, 435 (1945).
    [CrossRef]
  2. L. A. Jones and G. C. Higgins, J. Opt. Soc. Am. 36, 203 (1946).
    [CrossRef]
  3. L. A. Jones and G. C. Higgins, J. Opt. Soc. Am. 37, 217 (1947).
    [CrossRef] [PubMed]
  4. L. A. Jones and G. C. Higgins, J. Opt. Soc. Am. 38, 398 (1948).
    [CrossRef]
  5. L. A. Jones and G. C. Higgins, J. Opt. Soc. Am. 41, 41 (1951).
    [CrossRef]
  6. L. A. Jones and G. C. Higgins, J. Opt. Soc. Am. 41, 64 (1951).
    [CrossRef]
  7. L. A. Jones and G. C. Higgins, J. Opt. Soc. Am. 41, 192 (1951).
    [CrossRef]
  8. Jones, Higgins, and Stultz, J. Opt. Soc. Am. 45, 107 (1955).
    [CrossRef]
  9. H. Zweig, J. Opt. Soc. Am. 46, 805, 812 (1956).
    [CrossRef]
  10. R. Clark Jones, J. Opt. Soc. Am. 45, 799 (1955).
    [CrossRef]
  11. A. Marriage and E. Pitts, J. Opt. Soc. Am. 46, 1019 (1956).
    [CrossRef]
  12. J. H. Altman and K. F. Stultz, Rev. Sci. Instr. 27, 1033 (1956).
    [CrossRef]
  13. J. H. Altman and K. F. Stultz, Phot. Sci. Tech. (to be published).
  14. M. H. Sweet, J. Opt. Soc. Am. 37, 432 (1947); Electronics 19, 105 (November, 1946).
    [CrossRef]
  15. N. R. Gunderson, U. S. Patent2,454,871 (1948).
  16. J. G. Clarke, Electronics 17, 138 (November, 1944). The type of differentiator used is illustrated by his Fig. 6.
  17. L. A. Jones and N. Deisch, J. Franklin Inst. 190, 657 (1920).
    [CrossRef]
  18. E. M. Lowry, J. Opt. Soc. Am. 26, 65 (1936).
    [CrossRef]
  19. L. A. Jones, J. Franklin Inst. 190, 39 (1920), p. 50.
    [CrossRef]
  20. Processing Chemicals and Formulas for Black-and-White Photography (Eastman Kodak Company, Rochester, 1954), fifth edition, p. 40.

1956 (3)

1955 (2)

1951 (3)

1948 (1)

1947 (2)

1946 (1)

1945 (1)

1944 (1)

J. G. Clarke, Electronics 17, 138 (November, 1944). The type of differentiator used is illustrated by his Fig. 6.

1936 (1)

1920 (2)

L. A. Jones and N. Deisch, J. Franklin Inst. 190, 657 (1920).
[CrossRef]

L. A. Jones, J. Franklin Inst. 190, 39 (1920), p. 50.
[CrossRef]

Altman, J. H.

J. H. Altman and K. F. Stultz, Rev. Sci. Instr. 27, 1033 (1956).
[CrossRef]

J. H. Altman and K. F. Stultz, Phot. Sci. Tech. (to be published).

Clark Jones, R.

Clarke, J. G.

J. G. Clarke, Electronics 17, 138 (November, 1944). The type of differentiator used is illustrated by his Fig. 6.

Deisch, N.

L. A. Jones and N. Deisch, J. Franklin Inst. 190, 657 (1920).
[CrossRef]

Gunderson, N. R.

N. R. Gunderson, U. S. Patent2,454,871 (1948).

Higgins,

Higgins, G. C.

Jones,

Jones, L. A.

Lowry, E. M.

Marriage, A.

Pitts, E.

Stultz,

Stultz, K. F.

J. H. Altman and K. F. Stultz, Rev. Sci. Instr. 27, 1033 (1956).
[CrossRef]

J. H. Altman and K. F. Stultz, Phot. Sci. Tech. (to be published).

Sweet, M. H.

Zweig, H.

Electronics (1)

J. G. Clarke, Electronics 17, 138 (November, 1944). The type of differentiator used is illustrated by his Fig. 6.

J. Franklin Inst. (2)

L. A. Jones and N. Deisch, J. Franklin Inst. 190, 657 (1920).
[CrossRef]

L. A. Jones, J. Franklin Inst. 190, 39 (1920), p. 50.
[CrossRef]

J. Opt. Soc. Am. (13)

Rev. Sci. Instr. (1)

J. H. Altman and K. F. Stultz, Rev. Sci. Instr. 27, 1033 (1956).
[CrossRef]

Other (3)

J. H. Altman and K. F. Stultz, Phot. Sci. Tech. (to be published).

N. R. Gunderson, U. S. Patent2,454,871 (1948).

Processing Chemicals and Formulas for Black-and-White Photography (Eastman Kodak Company, Rochester, 1954), fifth edition, p. 40.

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Figures (12)

Fig. 1
Fig. 1

Threshold-gradient sensitivity of human eye for graininess, from Fig. 6 of reference 8. The calibration curve of the granularity meter has the same shape but the ordinates are meter readings.

Fig. 2
Fig. 2

General view of instrument for the routine measurement of granularity.

Fig. 3
Fig. 3

Optical system of the instrument. The dashed boxes indicate that the elements within them can be moved as a unit as well as individually. All the elements indicated by the same letter are conjugate to one another.

Fig. 4
Fig. 4

Block diagram of the electrical system of the instrument.

Fig. 5
Fig. 5

Graininess in terms of meter readings. The curve for the variable signal was made with meter readings set in accordance with Fig. 1 as the density varied. The curves for constant signal were made for the indicated meter readings.

Fig. 6
Fig. 6

Graininess curves for three typical negative materials, A, B, and C. ➀, Variable signal; ➁, signal appropriate to D=0.8, regardless of density.

Fig. 7
Fig. 7

Granularity curves of two materials for a meter reading appropriate to D=0.8. Class I graininess values are 121 for A and 159 for B.

Fig. 8
Fig. 8

Typical characteristic curve to illustrate the sensitometric terminology discussed in text.

Fig. 9
Fig. 9

Tone-reproduction cycle for two negative materials developed to matched values of θ. The minimum luminance was recorded on the scale of log exposure 0.3 unit above the speed point.

Fig. 10
Fig. 10

Tone-reproduction curves of pictures made from negatives E, F, and G. A, pictures for which data are given in Table I; B, pictures for which data are given in Table II.

Fig. 11
Fig. 11

Relation between percent separation of prints as judged subjectively and the percent difference in as determined objectively. Data from Table I.

Fig. 12
Fig. 12

Typical curves used for determining Class II graininess or relative print graininess, which in this case is 705.

Tables (3)

Tables Icon

Table I Characteristics of materials used for comparing Class II measurements with matched 20× enlargements judged subjectively.

Tables Icon

Table II Class I measurements of graininess on five materials listed in Table I. Column 7 is based on column 6 of Table I.

Tables Icon

Table III Comparison of alternative method of determining relative print graininess with the rigorous method. The standard value of average gradient is θs=0.65. Values obtained by the alternative method are in column 5 while values obtained by following the Class II procedure are in column 6 (from column 4 of Table I). Percentage differences are in the last column; a plus sign indicates that the value obtained by the alternative procedure is the higher.

Equations (3)

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H = 1000 / M .
M = ( 2000 / 17.18 ) ( 1.5 ) / Ø c r = 175 / Ø c r ,
H = 1000 Ø c r / 175 = 5.72 Ø c r ,