Abstract

This paper deals with the effect on contrast thresholds of the fluctuations in the background luminance or “luminance noise.” Targets of several sizes are produced on a television screen, imbedded in fine-grain luminance noise of controllable magnitude. The results indicate that luminance fluctuations of small magnitude do not affect the threshold very much when the mean luminance of the screen is 0.01 and 0.1 ft-L, while they do change it appreciably at 1.0 ft-L. When luminance fluctuations are large, contrast thresholds at the above three luminance levels are nearly the same, indicating that the degree of luminance fluctuation governs the contrast threshold.

The extent to which luminance noise increases the contrast threshold is used to estimate the internal noise of the vision channel and an attempt is made to compare this with the noise that might be expected on account of fluctuations in the number of quanta absorbed in the retina.

© 1964 Optical Society of America

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References

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  1. J. W. R. Griffiths and N. S. Nagaraja, J. Brit. Inst. Radio Engr. 25 (3), 225 (1963).
  2. A. Rose, J. Opt. Soc. Am.,  38, 196 (1948).
    [Crossref] [PubMed]
  3. H. B. Barlow, J. Physiol., London 136, 469 (1957).
  4. H. B. Barlow, J. Physiol., London 141, 337 (1958).
  5. R. L. Gregory, Information Theory 3rd London Symposium, September 1955 (Butterworths Scientific Publications Ltd., London, 1955), 287.
  6. Contrast is expressed here in dB, as 10 logC.
  7. R. E. Burgess, Phil. Mag. 42, 475 (1951).
  8. J. L. Lawson and G. E. Uhlenbeck, Threshold Signals, Radiation Laboratory Series, Vol. 24 (McGraw-Hill Book Company Inc., New York), 167.
  9. Yves Le Grand, Light, Colour and Vision (Chapman & Hall Ltd., London, England, 1957), 104.

1963 (1)

J. W. R. Griffiths and N. S. Nagaraja, J. Brit. Inst. Radio Engr. 25 (3), 225 (1963).

1958 (1)

H. B. Barlow, J. Physiol., London 141, 337 (1958).

1957 (1)

H. B. Barlow, J. Physiol., London 136, 469 (1957).

1951 (1)

R. E. Burgess, Phil. Mag. 42, 475 (1951).

1948 (1)

Barlow, H. B.

H. B. Barlow, J. Physiol., London 141, 337 (1958).

H. B. Barlow, J. Physiol., London 136, 469 (1957).

Burgess, R. E.

R. E. Burgess, Phil. Mag. 42, 475 (1951).

Gregory, R. L.

R. L. Gregory, Information Theory 3rd London Symposium, September 1955 (Butterworths Scientific Publications Ltd., London, 1955), 287.

Griffiths, J. W. R.

J. W. R. Griffiths and N. S. Nagaraja, J. Brit. Inst. Radio Engr. 25 (3), 225 (1963).

Lawson, J. L.

J. L. Lawson and G. E. Uhlenbeck, Threshold Signals, Radiation Laboratory Series, Vol. 24 (McGraw-Hill Book Company Inc., New York), 167.

Le Grand, Yves

Yves Le Grand, Light, Colour and Vision (Chapman & Hall Ltd., London, England, 1957), 104.

Nagaraja, N. S.

J. W. R. Griffiths and N. S. Nagaraja, J. Brit. Inst. Radio Engr. 25 (3), 225 (1963).

Rose, A.

Uhlenbeck, G. E.

J. L. Lawson and G. E. Uhlenbeck, Threshold Signals, Radiation Laboratory Series, Vol. 24 (McGraw-Hill Book Company Inc., New York), 167.

J. Brit. Inst. Radio Engr. (1)

J. W. R. Griffiths and N. S. Nagaraja, J. Brit. Inst. Radio Engr. 25 (3), 225 (1963).

J. Opt. Soc. Am. (1)

J. Physiol., London (2)

H. B. Barlow, J. Physiol., London 136, 469 (1957).

H. B. Barlow, J. Physiol., London 141, 337 (1958).

Phil. Mag. (1)

R. E. Burgess, Phil. Mag. 42, 475 (1951).

Other (4)

J. L. Lawson and G. E. Uhlenbeck, Threshold Signals, Radiation Laboratory Series, Vol. 24 (McGraw-Hill Book Company Inc., New York), 167.

Yves Le Grand, Light, Colour and Vision (Chapman & Hall Ltd., London, England, 1957), 104.

R. L. Gregory, Information Theory 3rd London Symposium, September 1955 (Butterworths Scientific Publications Ltd., London, 1955), 287.

Contrast is expressed here in dB, as 10 logC.

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Figures (4)

F. 1
F. 1

Experimental setup: (A) Target presentation apparatus; (B) E.M.I. television camera; (C) preamplifier; (D) television monitor; (E) noise generator; (F) timing units; (G) random target selector. Waveforms over a part of one raster line are shown. Inputs to the monitor (i) signal+noise, (ii) synchronizing pulses, (iii) suppression pulses, (iv) lift voltage.

F. 2
F. 2

(A) Percent contrast thresholds for three target sizes at 0.1 ft-L. Scale at right: percent contrast for 5.7′. Scale at left: Percent contrast for 14.7′ and 32′. (B) Percent contrast thresholds at three luminance levels for 14.7′ target.

F. 3
F. 3

(Threshold contrast)2×103 vs Brms2: (A) 0.01 ft-L; (B) 0.1 ft-L; (C) 1 ft-L.

F. 4
F. 4

(Threshold contrast)2 vs Brms2. Target sizes: (A) 5.7 min; (B) 14.7 min; (C) 32 min. Ordinates: left-hand scale multiplied by 103 for (A) and 105 for (C); right-hand scale-multiplied by 104 for (B). Luminance, 1.0 ft-L for all tests.

Equations (9)

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B = K e n ,
Δ B = K ρ 2 ,
10 log C 1 10 log C 2 = 20 log ρ 1 20 log ρ 2 ;
10 log C 2 = 10 log C 1 20 ( log ρ 1 log ρ 2 ) .
( Δ B / B ) 0 = K , B int ;
( Δ B / B ) 1 = K , B rms ;
( Δ B / B ) 2 = K , f ( B int , B rms ) .
f ( B int , B rms ) = ( B int 2 + B rms 2 ) 1 2 ,
( Δ B / B ) 2 2 = K 2 ( B int 2 + B rms 2 ) .