Effective contrast of colored stimuli in the mesopic range: a metric for perceived contrast based on achromatic luminance contrast.

Little is known about how color signals and cone- and rod-based luminance signals contribute to perceived contrast in the mesopic range. In this study the perceived contrast of colored, mesopic stimuli was matched with that of spatially equivalent achromatic stimuli. The objective was to develop a metric for perceived contrast in the mesopic range in terms of an equivalent achromatic luminance contrast, referred to here as effective contrast. Stimulus photopic luminance contrast, scotopic luminance contrast, and chromatic difference from the background all contributed to effective contrast over the mid-mesopic range, but their contributions were not independent and varied markedly with background luminance. Surprisingly, color made a significant contribution to effective contrast from 10 to approximately 0.003 cd m(-2). A model describing this relationship is introduced (R2 = 0.89) and compared with predictions of mesopic luminance contrast obtained from a number of models proposed as systems of mesopic photometry.

[1]  K. Nakayama,et al.  Stimulus discriminability in visual search , 1994, Vision Research.

[2]  C. Koch,et al.  A saliency-based search mechanism for overt and covert shifts of visual attention , 2000, Vision Research.

[3]  P. W. Trezona,et al.  A system of mesopic photometry , 1991 .

[4]  N. Parry.  Contrast dependence of reaction times to chromatic gratings , 2001 .

[5]  J. Pokorny,et al.  Brightness of equal-luminance lights. , 1982, Journal of the Optical Society of America.

[6]  H. Yaguchi,et al.  Subadditivity and superadditivity in heterochromatic brightness matching , 1983, Vision Research.

[7]  D. A. Palmer.  Standard observer for large-field photometry at any level. , 1968, Journal of the Optical Society of America.

[8]  W. R. Brown,et al.  The influence of luminance level on visual sensitivity to color differences. , 1951, Journal of the Optical Society of America.

[9]  W D Wright,et al.  The sensitivity of the eye to small colour differences , 1941 .

[10]  R. M. Boynton,et al.  Visibility of borders: separate and combined effects of color differences, luminance contrast, and luminance level. , 1981, Journal of the Optical Society of America.

[11]  Miyoshi Ayama,et al.  Brightness-to-luminance ratio of colored light in the entire chromaticity diagram , 1998 .

[12]  K. Sagawa,et al.  System of mesopic photometry for evaluating lights in terms of comparative brightness relationships , 1992 .

[13]  W K Adrian,et al.  Influence of Field Size on the Spectral Sensitivity of the Eye in the Photopic and Mesopic Range , 1985, American journal of optometry and physiological optics.

[14]  T. Cornsweet,et al.  The staircrase-method in psychophysics. , 1962, The American journal of psychology.

[15]  M. Rea,et al.  A system of mesopic photometry , 1998 .

[16]  D. L. Macadam.  Visual Sensitivities to Color Differences in Daylight , 1942 .

[17]  Vivianne C. Smith,et al.  Reaction times to chromatic stimuli , 1985, Vision Research.

[18]  J. A. Harlow,et al.  Measurements of chromatic sensitivity in the mesopic range , 2001 .

[19]  Preeti Verghese,et al.  The psychophysics of visual search , 2000, Vision Research.

[20]  Michael D'Zmura,et al.  Color in visual search , 1991, Vision Research.

[21]  Elek Ludvigh,et al.  EFFECT OF REDUCED CONTRAST ON VISUAL ACUITY AS MEASURED WITH SNELLEN TEST LETTERS , 1941 .

[22]  M. Ikeda,et al.  Equivalent lightness of colored objects at illuminances from the scotopic to the photopic level , 1989 .

[23]  P. Kaiser,et al.  Contributions of the opponent mechanisms to brightness and nonlinear models , 1988, Vision Research.

[24]  D. A. Palmer,et al.  A System of Mesopic Photometry , 1966, Nature.

[25]  A. Nagy,et al.  Critical color differences determined with a visual search task. , 1990, Journal of the Optical Society of America. A, Optics and image science.

[26]  S. Shioiri,et al.  Individual differences of the contribution of chromatic channels to brightness. , 1993, Journal of the Optical Society of America. A, Optics and image science.

[27]  Ken Sagawa,et al.  Mesopic spectral luminous efficiency functions : Final experimental report , 1987 .

[28]  Robert M. Boynton,et al.  Chromatic difference steps of moderate size measured along theoretically critical axes , 1980 .

[29]  S. Anstis.  The Purkinje rod-cone shift as a function of luminance and retinal eccentricity , 2002, Vision Research.

[30]  L. Mahon,et al.  Color and luminance detection and discrimination asymmetries and interactions , 1998, Vision Research.

[31]  A. Hendrickson,et al.  Human photoreceptor topography , 1990, The Journal of comparative neurology.

[32]  Dennis M. Levi,et al.  Reaction time as a measure of suprathreshold grating detection , 1978, Vision Research.

[33]  Gordon E. Legge,et al.  Psychophysics of reading—V. The role of contrast in normal vision , 1987, Vision Research.

[34]  C. R. Ingling,et al.  The relationship between spectral sensitivity and spatial sensitivity for the primate r-g X-channel , 1983, Vision Research.

[35]  H R BLACKWELL,et al.  Contrast thresholds of the human eye. , 1946, Journal of the Optical Society of America.

[36]  Mitsuo Ikeda,et al.  Equivalent lightness of colored objects of equal munsell chroma and of equal munsell value at various illuminances , 1991 .

[37]  Ilpo Kojo,et al.  Effect of stimulus contrast on performance and eye movements in visual search , 2001, Vision Research.

[38]  J L Barbur,et al.  Visual processing levels revealed by response latencies to changes in different visual attributes , 1998, Proceedings of the Royal Society of London. Series B: Biological Sciences.

[39]  H. Walkey.  Visual performance in the mesopic range , 2003 .