Dear Roy

This is a paper from 2000, which lists coordinates of equally detectable colors:

Evidence for the contribution of S cones to the detection of flicker brightness and red–green. Harald J. Teufel and Christian Wehrhahn. JOSA A, Vol. 17, Issue 6, pp. 994-1006 (2000)

Hope this helps :)

Dear Christian

thanks for your reply. I will try these ASAP

Roy

I hope some of these references may help (although they do not give you directly the answer to your question):

Chromatic settings and the structural color constancy index. Roca-Vila J, Parraga CA, Vanrell M. J Vis. 2013 Mar 11;13(4). doi:pii: 3. 10.1167/13.4.3.

Color coding in the cortex: a modified approach to bottom-up visual attention. Ramirez-Villegas JF, Ramirez-Moreno DF. Biol Cybern. 2013 Feb;107(1):39-47. doi: 10.1007/s00422-012-0522-6. Epub 2012 Sep 28.

Uniform color spaces and natural image statistics. McDermott KC, Webster MA. J Opt Soc Am A Opt Image Sci Vis. 2012 Feb 1;29(2):A182-7. doi: 10.1364/JOSAA.29.00A182.

Naming versus matching and the stability of unique hues. Panorgias A, Kulikowski JJ, Parry NR, McKeefry DJ, Murray IJ. Ophthalmic Physiol Opt. 2010 Sep;30(5):553-9. doi: 10.1111/j.1475-1313.2010.00736.x.

Flicker between equal-luminance colors examined with multidimensional scaling. Bimler D. J Opt Soc Am A Opt Image Sci Vis. 2010 Mar 1;27(3):523-31. doi: 10.1364/JOSAA.27.000523.

Functional computational model for optimal color coding. Romney AK, Chiao CC. Proc Natl Acad Sci U S A. 2009 Jun 23;106(25):10376-81. doi: 10.1073/pnas.0904688106. Epub 2009 Jun 3.

Collinear facilitation in color vision. Huang PC, Mullen KT, Hess RF. J Vis. 2007 Aug 23;7(11):6.1-14.

Pupil response to color signals in cone-contrast space. Tsujimura S, Wolffsohn JS, Gilmartin B. Curr Eye Res. 2006 May;31(5):401-8.

Toward a CIE supplementary system of photometry: brightness at any level including mesopic vision. Sagawa K. Ophthalmic Physiol Opt. 2006 May;26(3):240-5. Review.

Are cone sensitivities determined by natural color statistics? Lewis A, Zhaoping L. J Vis. 2006 Mar 21;6(3):285-302.

The simple perfection of quantum correlation in human vision. Bouman MA. Prog Neurobiol. 2006 Jan;78(1):38-60. Epub 2005 Dec 27. Review.

A luminous efficiency function, V*(lambda), for daylight adaptation. Sharpe LT, Stockman A, Jagla W, Jägle H. J Vis. 2005 Dec 21;5(11):948-68.

The cone inputs to the unique-hue mechanisms. Wuerger SM, Atkinson P, Cropper S. Vision Res. 2005 Nov;45(25-26):3210-23. Epub 2005 Aug 8.

Induction effects for heterochromatic brightness matching, heterochromatic flicker photometry, and minimally distinct border: implications for the neural mechanisms underlying induction. Gunther KL, Dobkins KR. J Opt Soc Am A Opt Image Sci Vis. 2005 Oct;22(10):2182-96.

Spectrally opponent inputs to the human luminance pathway: slow +M and -L cone inputs revealed by intense long-wavelength adaptation. Stockman A, Plummer DJ, Montag ED. J Physiol. 2005 Jul 1;566(Pt 1):61-76. Epub 2005 Apr 28.

Spectrally opponent inputs to the human luminance pathway: slow +L and -M cone inputs revealed by low to moderate long-wavelength adaptation. Stockman A, Plummer DJ. J Physiol. 2005 Jul 1;566(Pt 1):77-91. Epub 2005 Apr 28.

Associating color appearance with the cone chromaticity space. Cao D, Pokorny J, Smith VC. Vision Res. 2005 Jul;45(15):1929-34.

Simple reaction times in color space: the influence of chromaticity, contrast, and cone opponency. McKeefry DJ, Parry NR, Murray IJ. Invest Ophthalmol Vis Sci. 2003 May;44(5):2267-76.

Silly question, but is Your monitor calibrated? Did you measure the luminance of the colors you used? Even if the luminance between two colors are the same, the perceived luminance will differ between individuals.

Dear Roy, we implemented several experimental protocols in order to detect early signs of multiple sclerosis. For this purpose we used pC high-quality monitors in order to provide color visual stimuli to the patients of the Neurological Dept of the Umberto I° University Hospital of Roma Sapienza. At your request I can send you more details ([email protected] ). See also.

FILLIGOI G.C., CAPITANIO L., ACCORNERO N. "Chromatic perception test: a computer based approach" Proc. IEEE/EMBS Int. Conf., Amsterdam (The Netherlands), 31 Oct - 3 Nov 1996

N.ACCORNERO, S. RINALDUZZI, M. FILIPPI, E. MILLEFIORINI, G.C. FILLIGOI, L. CAPITANIO "Computerized color perimetry in multiple sclerosis" Multiple Sclerosis, 1998, 4, 79-84