Abstract

Definition, as the term is used in the present paper, is the quality aspect of photographs that is associated with the clarity of detail. Resolving power is used in its customary sense, and sharpness is defined as the impression received by an observer viewing well-resolved elements of detail; its objective correlate is acutance, which has been defined quantitatively elsewhere. A series of negatives was made of a scene, the lens being moved longitudinally between exposures to vary the resolving power and the acutance in the negatives. A corresponding set of negatives was made of resolving power and acutance test objects. Positive transparencies were made from both sets of negatives. The transparencies of the scene were judged for definition, and numerical values were assigned by statistical methods. Neither acutance nor resolving power correlated well with definition except when the resolving power exceeded the limit set by the eye, in which case acutance correlated fairly well. A practical correlate of definition is proposed which consists of acutance multiplied by an exponential function of resolving power.

© 1955 Optical Society of America

Full Article  |  PDF Article

References

  • View by:
  • |
  • |
  • |

  1. R. N. Wolfe and F. C. Eisen, J. Opt. Soc. Am. 43, 914 (1953).
    [Crossref]
  2. G. C. Higgins and L. A. Jones, J. Soc. Motion Picture and Television Engrs. 58, 277 (1952); PSA Journal (Phot. Sci. and Technique) 19B, 55 (1953).
  3. W. Weinstein, Phot. J. 91B, 138 (1951).
  4. L. L. Thurstone, Am. J. Psychol. 38, 368 (1927).
    [Crossref]
  5. J. H. Morrissey, J. Opt.. Soc. Am. (to be published); for abstract, see J. Opt. Soc. Am. 43, 821 (1953).
  6. F. H. Perrin and J. H. Altman, J. Opt. Soc. Am. 41, 265 (1951).
    [Crossref]
  7. E. W. H. Selwyn, Phot. J. 88B, 46 (1948).

1953 (1)

1952 (1)

G. C. Higgins and L. A. Jones, J. Soc. Motion Picture and Television Engrs. 58, 277 (1952); PSA Journal (Phot. Sci. and Technique) 19B, 55 (1953).

1951 (2)

1948 (1)

E. W. H. Selwyn, Phot. J. 88B, 46 (1948).

1927 (1)

L. L. Thurstone, Am. J. Psychol. 38, 368 (1927).
[Crossref]

Altman, J. H.

Eisen, F. C.

Higgins, G. C.

G. C. Higgins and L. A. Jones, J. Soc. Motion Picture and Television Engrs. 58, 277 (1952); PSA Journal (Phot. Sci. and Technique) 19B, 55 (1953).

Jones, L. A.

G. C. Higgins and L. A. Jones, J. Soc. Motion Picture and Television Engrs. 58, 277 (1952); PSA Journal (Phot. Sci. and Technique) 19B, 55 (1953).

Morrissey, J. H.

J. H. Morrissey, J. Opt.. Soc. Am. (to be published); for abstract, see J. Opt. Soc. Am. 43, 821 (1953).

Perrin, F. H.

Selwyn, E. W. H.

E. W. H. Selwyn, Phot. J. 88B, 46 (1948).

Thurstone, L. L.

L. L. Thurstone, Am. J. Psychol. 38, 368 (1927).
[Crossref]

Weinstein, W.

W. Weinstein, Phot. J. 91B, 138 (1951).

Wolfe, R. N.

Am. J. Psychol. (1)

L. L. Thurstone, Am. J. Psychol. 38, 368 (1927).
[Crossref]

J. Opt. Soc. Am. (2)

J. Soc. Motion Picture and Television Engrs. (1)

G. C. Higgins and L. A. Jones, J. Soc. Motion Picture and Television Engrs. 58, 277 (1952); PSA Journal (Phot. Sci. and Technique) 19B, 55 (1953).

Phot. J. (2)

W. Weinstein, Phot. J. 91B, 138 (1951).

E. W. H. Selwyn, Phot. J. 88B, 46 (1948).

Other (1)

J. H. Morrissey, J. Opt.. Soc. Am. (to be published); for abstract, see J. Opt. Soc. Am. 43, 821 (1953).

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 (17)

Fig. 1
Fig. 1

Arrangement of camera and projector for obtaining the transparencies to be judged for definition.

Fig. 2
Fig. 2

Section of the field of camera lens represented by the transparencies.

Fig. 3
Fig. 3

Reproduction of typical transparency judged for definition.

Fig. 4
Fig. 4

Arrangement of camera and test objects for obtaining the transparencies to be measured for resolving power and acutance.

Fig. 5
Fig. 5

Test objects for measuring resolving power and acutance.

Fig. 6
Fig. 6

Definition in σ units as a function of the distance of the film from the lens.

Fig. 7
Fig. 7

Reproduction (enlarged) of the image of test objects on the axis at focal position 2, where acutance is high but resolving power is low.

Fig. 8
Fig. 8

Reproduction (enlarged) of the image of test objects 15° from the axis at focal position 2, where acutance is low but resolving power is high. The center of the field is at the left of this photograph.

Fig. 9
Fig. 9

Resolving power as a function of field angle for each focal position.

Fig. 10
Fig. 10

Typical density distribution in an image formed by a knife-edge.

Fig. 11
Fig. 11

Extreme examples of edge-gradient curves encountered in the present investigation. Curve 1 had the lowest acutance (45) and curve 2 the highest (3470). Points A and B are the limits between which acutance was computed.

Fig. 12
Fig. 12

Acutance as a function of field angle for each focal position.

Fig. 13
Fig. 13

Resolving power, acutance, and the combined function described in the text as a function of field angle for focal position 2.

Fig. 14
Fig. 14

Definition in σ units as a function of the logarithm of 〈RPAv, the mean resolving power over the picture, and of 〈A′〉Av, the mean acutance.

Fig. 15
Fig. 15

Graph of the function of resolving power that is proposed for modifying the values of acutance to furnish an objective correlate of definition.

Fig. 16
Fig. 16

Proposed objective correlate of definition, log A′·f(RP), as a function of field angle for each focal position.

Fig. 17
Fig. 17

Definition as a function of log〈A′·f(RP)〉Av for each focal position. The straight line was drawn by the method of least squares.

Tables (1)

Tables Icon

Table I Definition of picture transparencies and mean values of resolving power, acutance, and the combined function (in logarithmic terms) described in text for each focal position.

Equations (3)

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

f ( R P ) = 1 - e - K · R P 2 .
A · f ( R P ) = A [ 1 - e - K · ( R P ) 2 ]
A · ( 1 - e - 0.007 R P 2 )