Intrinsic gray

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Intrinsic gray
 
Components
RGB ( r , g , b ) (22, 22, 29)
Hexadecimal triplet 16161D
CMYK ( c , m , y , k ) (24%, 24%, 0%, 89%)
HSL ( h , s , l ) (240 °, 14%, 10%)

Eigengrau , also Eigenlicht (the German terms are also common in the English-speaking world) or self-noise , is the color you see in complete darkness . The term was introduced by Gustav Theodor Fechner around 1860 . At that time it was noticeable that the sensitivity of the eye deviates from the prediction of Fechner's law for very large as well as very small brightnesses .

Intrinsic gray is perceived as brighter than black objects under normal lighting conditions. This is because the contrast is more important than the actual brightness in perception. For example, the night sky appears darker than its own gray because of the contrast created by the stars . A pure black perception of the eye is only possible with a simultaneous contrast to a white perception, as Ewald Hering described in 1874.

Action potentials of the optic nerve are seen as the cause of the inherent grayness, possibly caused by a kind of background noise in the retina . These accidental stimuli cannot be distinguished from those which come from light particles. The cause could be thermally induced isomerizations of the visual pigment rhodopsin . But there are also other hypotheses.

Hermann von Helmholtz attributed the lower sensitivity of the eye to low light intensity to the blotchiness of the intrinsic gray.

The term self-noise is also used in other contexts, including acoustics . The inherent noise of microphones is quantified with the equivalent noise level . An analogy to self-noise can also be found with photo cells , especially with the dark noise of the sensors of digital cameras.

!! Intrinsic gray and black in comparison

Individual evidence

  1. ↑ a b c Jan Dirk Blom: A Dictionary of Hallucinations . Springer, December 8, 2009, ISBN 978-1-4419-1223-7 , pp. 170–.
  2. ↑ a b Hermann vonHelmholtz: The disturbance of the perception of the smallest differences in brightness by the own light of the retina . Journal of Psychology and Physiology of the Sensory Organs, 1 (1890) ( online )
  3. ^ Hans Wallach: Brightness Constancy and the Nature of Achromatic Colors . In: Journal of Experimental Psychology . 38, No. 3, 1948, pp. 310-324. doi : 10.1037 / h0053804 . PMID 18865234 .
  4. ^ Werner Backhaus, Reinhold Kliegl, John Simon Werner: Color Vision: Perspectives from Different Disciplines . Walter de Gruyter, January 1, 1998, ISBN 978-3-11-015431-3 , pp. 188–.
  5. ↑ Horace Barlow: Dark and Light Adaptation: Psychophysics. . In: Visual Psychophysics . Springer-Verlag, New York 1972, ISBN 0-387-05146-5 .
  6. ^ Horace Barlow: Retinal and Central Factors in Human Vision Limited by Noise . In: Vertebrate Photoreception . Academic Press, New York 1977, ISBN 0-12-078950-7 .
  7. ^ DA Baylor, G Matthews, K.-W. Yau: Two components of electrical dark noise in toad retinal rod outer segments . In: The Journal of Physiology . 309, 1980, pp. 591-621. PMID 6788941 . PMC 1274605 (free full text).