Abstract

Data obtained with the variable-magnification graininess instrument described in Part V of this series of communications are given showing the variation of graininess as a function of the luminance of the test field, the luminance of the various components of the observer’s field, the viewing distance, and the angular subtense of the test field. On the basis of these data, standard conditions for the various variables are established for the measurement of graininess. Graininess measurements in terms of blending magnification at a constant viewing distance are compared with graininess measurements in terms of blending distance at a constant magnification.

© 1951 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. 41, 41 (1951).
    [Crossref]
  2. M. Luckiesh and S. A. Moss, J. Opt. Soc. Am. 31, 594 (1941).
    [Crossref]
  3. F. M. Urban, Applications of Statistical Methods to Problems of Psychophysics (Psychological Clinic Press, Philadelphia, Pennsylvania, 1908).
  4. P. Moon, Scientific Basis of Illuminating Engineering (McGraw-Hill Book Company, Inc., New York, 1936), p. 419.
  5. R. J. Lythgoe, Reports of the Medical Research Council Committee upon the Physiology of Vision. X. The measurement of visual acuity (His Majesty’s Stationery Office, London, 1932), p. 30.

1951 (1)

1941 (1)

Higgins, G. C.

Jones, L. A.

Luckiesh, M.

Lythgoe, R. J.

R. J. Lythgoe, Reports of the Medical Research Council Committee upon the Physiology of Vision. X. The measurement of visual acuity (His Majesty’s Stationery Office, London, 1932), p. 30.

Moon, P.

P. Moon, Scientific Basis of Illuminating Engineering (McGraw-Hill Book Company, Inc., New York, 1936), p. 419.

Moss, S. A.

Urban, F. M.

F. M. Urban, Applications of Statistical Methods to Problems of Psychophysics (Psychological Clinic Press, Philadelphia, Pennsylvania, 1908).

J. Opt. Soc. Am. (2)

Other (3)

F. M. Urban, Applications of Statistical Methods to Problems of Psychophysics (Psychological Clinic Press, Philadelphia, Pennsylvania, 1908).

P. Moon, Scientific Basis of Illuminating Engineering (McGraw-Hill Book Company, Inc., New York, 1936), p. 419.

R. J. Lythgoe, Reports of the Medical Research Council Committee upon the Physiology of Vision. X. The measurement of visual acuity (His Majesty’s Stationery Office, London, 1932), p. 30.

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Figures (18)

Fig. 1
Fig. 1

Comparison of graininess measurements using ground-glass screen (A) and magnesium carbonate screen (B). Curve C represents data with magnesium carbonate screen when used with Jones-Deisch graininess instrument, and curve D is curve A multiplied by 0.6.

Fig. 2
Fig. 2

Comparison of graininess measurements made: (A) with a variable-magnification and constant viewing-distance technique; (B) with a constant-magnification and variable viewing-distance technique.

Fig. 3
Fig. 3

Variation of the ratio of viewing distance to blending magnification as a function of viewing distance, with the test field having a constant angular subtense of 2 degrees. Area surrounding test field is dark.

Fig. 4
Fig. 4

Variation of graininess as a function of the angular subtense of the test field. Area surrounding test field is dark.

Fig. 5
Fig. 5

Psychometric function giving frequency of perception of graininess as a function of log magnification.

Fig. 6
Fig. 6

Repeatability of graininess readings by one observer.

Fig. 7
Fig. 7

Variation of the ratio of viewing distance to blending magnification as a function of viewing distance, with the test field having a constant angular subtense of 2 degrees. Luminance of area surrounding test field is 2 ft-L.

Fig. 8
Fig. 8

Variation of graininess as a function of the angular subtense of the test field. Luminance of area surrounding test field is 2 ft-L.

Fig. 9
Fig. 9

Graininess-density functions obtained as the luminance of the test field with no sample in place was varied. The test-field luminances were as follows: curve A, 8 ft-L; curve B, 12 ft-L; curve C, 30 ft-L; curve D, 50 ft-L; curve E, 65 ft-L; curve F, 100 ft-L.

Fig. 10
Fig. 10

Graininess-density functions obtained with the luminance of the annular border fixed at 30 ft-L and the luminance of the stabilizing field variable. The stabilizing-field luminances were as follows: curve A, 15 ft-L; curve B, 2 ft-L; curve C, 0 ft-L. Dots represent graininess-density function obtained under standard conditions of observation.

Fig. 11
Fig. 11

Graininess-density functions obtained with the luminance of the annular border fixed at 2 ft-L and the luminance of the stabilizing field variable. The stabilizing-field luminances were as follows: curve A, 15 ft-L; curve B, 2 ft-L; curve C, 0 ft-L. Dots represent graininess-density function obtained under standard conditions of observation.

Fig. 12
Fig. 12

Graininess-density functions obtained with the luminance of the annular border fixed at 0 ft-L and the luminance of the stabilizing field variable. The stabilizing-field luminances were as follows: curve A, 15 ft-L; curve B, 2 ft-L; curve C, 0 ft-L. Dots represent graininess-density function obtained under standard conditions of observation.

Fig. 13
Fig. 13

Graininess-density functions obtained when observer is allowed to adjust the luminance of the annular border to match the luminance of the test field for any value of sample density. The stabilizing-field luminances were as follows: curve A, 15 ft-L; curve B, 2 ft-L; curve C, 0 ft-L. Dots represent graininess-density function obtained under standard conditions of observation.

Fig. 14
Fig. 14

Graininess-density functions obtained with the stabilizing field at 2 ft-L but varying in angular subtense. Curve A is for a 76-degree stabilizing field; curve B, for a 51-degree field; curve C, for an 18-degree field; and curve D, for no field.

Fig. 15
Fig. 15

The luminance distribution in stabilizing and in peripheral fields of the observation room when reading graininess under the conditions adopted as standard.

Fig. 16
Fig. 16

Graininess-density function obtained: A, by binocular vision; and B, by monocular vision.

Fig. 17
Fig. 17

Graininess-density functions measured under standard conditions. Curve A is for a relatively coarse material; curve B for a material of medium graininess; and curve C for a relatively fine-grained material.

Fig. 18
Fig. 18

Graininess-density functions measured with the Jones-Deisch instrument. Curve A is for a relatively coarse material; curve B for a material of medium graininess; and curve C for a relatively fine-grained material. Data are for the same samples employed in obtaining data shown in Fig. 17.

Tables (3)

Tables Icon

Table I Variable viewing distance. Luminance of visual field areas: Bb, Bc, Bd≈0. Luminance of test field, Ba′ (no sample in place)=23.2 ft-L. Size of test field, 40-mm diameter. Magnification, M=26.2.

Tables Icon

Table II Repeatability of graininess readings by one observer.

Tables Icon

Table III Variation among graininess readings by three observers.

Equations (3)

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H d = K D / d ,
H = 1000 / M b ,
M 2 = M 1 ( D 2 / D 1 ) .