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## The intensity JND comes from Poisson neural noise: Implications for image coding

### Abstract

While the problems of image coding and audio coding have frequently been assumed to have similarities, specific sets of relationships have remained vague. One area where there should be a meaningful comparison is with central masking noise estimates, which define the codec's quantizer step size. In the past few years, progress has been made on this problem in the auditory domain (Allen and Neely, J. Acoust. Soc. Am., {\bf 102}, 1997, 3628-46; Allen, 1999, Wiley Encyclopedia of Electrical and Electronics Engineering, Vol. 17, p. 422-437, Ed. Webster, J.G., John Wiley \& Sons, Inc, NY). It is possible that some useful insights might now be obtained by comparing the auditory and visual cases. In the auditory case it has been shown, directly from psychophysical data, that below about 5 sones (a measure of loudness, a unit of psychological intensity), the loudness JND is proportional to the square root of the loudness $\DL(\L) \propto \sqrt{\L(I)}$. This is true for both wideband noise and tones, having a frequency of 250 Hz or greater. Allen and Neely interpret this to mean that the internal noise is Poisson, as would be expected from neural point process noise. It follows directly that the Ekman fraction (the relative loudness JND), decreases as one over the square root of the loudness, namely $\DL/\L \propto 1/\sqrt{\L}$. Above ${\L} = 5$ sones, the relative loudness JND $\DL/\L \approx 0.03$ (i.e., Ekman law). It would be very interesting to know if this same relationship holds for the visual case between brightness $\B(I)$ and the brightness JND $\DB(I)$. This might be tested by measuring both the brightness JND and the brightness as a function of intensity, and transforming the intensity JND into a brightness JND, namely $\DB(I) = \B(I+ \DI) - \B(I) \approx \DI \frac{d\B}{dI}.$ If the Poisson nature of the loudness relation (below 5 sones) is a general result of central neural noise, as is anticipated, then one would expect that it would also hold in vision, namely that $\DB(\B) \propto \sqrt{\B(I)}$. %The history of this problem is fascinating, starting with Weber and Fechner. It is well documented that the exponent in the S.S. Stevens' power law is the same for loudness and brightness (Stevens, 1961) \nocite{Stevens61a} (i.e., both brightness $\B(I)$ and loudness $\L(I)$ are proportional to $I^{0.3}$). Furthermore, the brightness JND data are more like Riesz's near miss data than recent 2AFC studies of JND measures \cite{Hecht34,Gescheider97}

Topics: Psychophysics
Year: 2000
OAI identifier: oai:cogprints.org:1513
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### Citations

1. (1961). The psychophysics of sensory function,”
2. (1934). Vision II. the nature of the photoreceptor process,”
3. (1997). Psychophysics: The Fundamentals, 3d edition, Lawrence Erlbaum Associates,
4. (1923). Experimental Psychology,
5. (1986). On the relation of intensity JNDs to loudness and neural noise,”
6. (1988). Psychophysical aspects of auditory intensity coding,” in Auditory Function,
7. (1995). Loudness perception and intensity coding,”
8. (1927). A law of comparitive judgment,”
9. (1997). Modeling the relation between the intensity JND and loudness for pure tones and wide–band noise,”
10. (1947). Sensitivity to changes in the intensity of white noise and its relation to masking and loudness,”
11. (1978). Fundamentals of scaling and psychophysics,
12. (1997). Sensation and Judgment, Lawrence Erlbaum Assoc.,
13. (1928). Differential intensity sensitivity of the ear for pure tones,”
14. (1933). Loudness, its definition, measurement, and calculation,”
15. (1994). The relationship between the difference limen (DL) in intensity and the masked threshold of sub-critical bandwidth signals,”
16. (1966). Signal Detection Theory and Psychophysics,
17. (1994). Fundamentals of Hearing, An Introduction,
18. (1950). On the masking pattern of a simple auditory stimulus,”
19. (1977). Intensity discrimination as a function of frequency and sensation level,”
20. (1947). The growth of auditory sensation,”
21. (1995). Speech and hearing in communication,” in The ASA edition of Speech and Hearing
22. (1965). The physics of the ear,
23. (1965). Some implications of the stochastic behavior of primary auditory
24. (1975). Auditory intensity discrimination with bursts of reproducible noise,”
25. (1953). Speech and Hearing in Communication, Robert E.
26. (1997). OHCs shift the excitation pattern via BM tension,” in Diversity
27. Derecruitment by multiband compression in hearing aids,” in The Efferent Auditory System,
28. (1996). Relation between the rate of growth of loudness and the intensity DL,” in Modeling Sensorineural Hearing
29. (1999). Somatic stiffness of cochlear outer hair cells is voltage-dependent,”
30. (1999). Is tectorial membrane filtering required to explain two tone suppression and the upward spread of masking?,” in Recent Developments
31. (1987). Whole cell currents and mechanical responses of isolated outer hair cells,”
32. (1996). DeRecruitment by multiband compression in hearing aids,” in Modeling Sensorineural Hearing Loss,
33. (1937). Dependence of hearing impairment on sound intensity,”
34. (1996). Harvey Fletcher’s role in the creation of communication acoustics,”
35. (1907). The complete form of Fechner’s law,”
36. (1924). The auditory masking of one pure tone by another and its probable relation to the dynamics of the inner ear,”
37. (1988). Der tastsinn und das gemainfu¨l,” in Handwo¨rterbuch
38. (1968). A study of the near–miss involving Weber’s law and pure tone intensity discrimination,”
39. (1988). Audition: Psychophysics and perception,”
40. (1970). Application of detection theory in psychophysics,”
41. (1951). Mathematics, measurement, and psychophysics,”
42. (1966). Translation of: Elemente der psychophysik,” in Elements of Psychophysics, Volume
43. (1993). Sound and Hearing, Lawrence Earlbaum Associates,

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