Nicolas P. Cottaris


417 Goddard Labs, 3710 Hamilton Walk


  • Ph.D. Vision Science, University of California at Berkeley, Berkeley, CA (2001)
  • M.S. Biomedical Engineering, Rutgers University, New Brunswick, NJ (1992)
  • B.S. Computer Science, University of Crete, Heraklion, Crete, Greece (1989)


Nicolas P. Cottaris is a Computational Vision Scientist and Senior Scientific Application Developer in the Brainard lab at the Computational Neuroscience Initiative ( of the University of Pennsylvania. He received a B.S. in Computer Science with emphasis on digital signal and image processing from the Univeristy of Crete, Greece (1989). He earned his M.S. in Biomedical Engineering from Rutgers Univerisity (1992), under Jerome Lettvin and E. Tzanakou, and his Ph.D. in Vision Science from the University of California at Berkeley (2001) under Russ DeValois. His doctoral work was focused on the spatio-temporal receptive field structure of cone inputs to neurons in the lateral geniculate nucleus and the primary visual cortex. Following his graduate studies, he moved to Kresge Eye Institute (Michigan), where he developed animal models and neurophysiologically-based methods for assessing the efficacy of artificial stimulation paradigms employed by retinal prosthetic devices. Currently, his work is focused on computational modeling of the early stages of the human visual system.

Research Interests

  • Computational modeling of the front-end of the visual system.


  • Psychophysical assessment of high-dynamic range displays.


  • Instrumentation in Vision Science, especially multi-primary displays and high-dynamic range displays.


Selected Publications

Cottaris, N. P., Wandell, B. A., Reike, F., Brainard, D. H. (2020). A computational observer model of spatial contrast sensitivity: Effects of photocurrent encoding, fixational eye movements, and inference engine. Journal of Vision, 20(7):17,

Ding, X., Radonjić, A., Cottaris, N. P., Jiang, H., Wandell, B. A., Brainard D. H. (2019). Computational-observer analysis of illumination discrimination. Journal of Vision, 19(7):11, doi: 10.1167/19.7.11,

Cottaris, N. P., Jiang, H., Ding, X., Wandell, B. A., Brainard, D. H. (2019). A computational observer model of spatial contrast sensitivity: Effects of wavefront-based optics, cone mosaic structure, and inference engine. Journal of Vision, 19(4):8, doi: 10.1167/19.4.8,

Tuten, W. S., Cooper, R. F., Tiruveedhula, P., Dubra, A., Roorda, A., Cottaris, N. P., Brainard, D. H., Morgan, J. I. W. (2018). Spatial summation in the human fovea: do normal optical aberrations and fixational eye movements have an effect? Journal of Vision, 18(8):6, doi: 10.1167/18.8.6,

Brainard, D. H., Cottaris, N. P., Radonjić, A. (2018). The perception of color and material in natural tasks. Royal Society Interface Focus, 8(4), doi: 10.1098/rsfs.2018.0012. Download PDF.

Radonjić, A., Cottaris, N. P., Brainard D. H. (2018). Quantifying how humans trade off color and material in object identification. Proceedings of Electronic Imaging 2018, Burlingame, CA. Download PDF.

Jiang, H., Cottaris, N., Golden, J., Brainard, D., Farrell, J. E., Wandell, B. A. (2017). Simulating retinal encoding: factors influencing Vernier acuity. Proceedings of Electronic Imaging 2017, Burlingame, CA. Download PDF. Also available on biorxiv:

Radonjić, A., Pearce, B. Aston, S., Krieger, A., Dubin, H., Cottaris, N. P., Brainard, D. H. & Hurlbert, A. C. (2016).  Illumination discrimination in real and simulated scenes. Journal of Vision, 16(11):2,, doi:10.1167/16.1.2.

Radonjic A., Cottaris N. P. & Brainard D. H. (2015) Color constancy supports cross-illumination color selection.  Journal of Vision, 15(6):13,,  doi: 10.1167/15.6.13.

Heasly, B. S., Cottaris, N. P., Lichtman, D. P., Xiao, X., & Brainard, D. H. (2014). RenderToolbox3: MATLAB tools that facilitate physically based stimulus rendering for vision research. Journal of Vision, 14(2:6),, doi: 10.1167/14.2.6. Access software.

Cottaris, N. P. & Brainard, D. H. (2015). Image preference for high and standard dynamic range images. Brainard Lab Technical Report 2015-2, Department of Psychology, University of Pennsylvania, Philadelphia, PA.  We thank David Hoffman for assistance with this work. Download PDF.  Code related to this report is available at

Cottaris, N. P. & Brainard, D. H. (2015). Assessing a prototype Samsung OLED TV panel for use in visual psychophysics. Brainard Lab Technical Report 2015-1, Department of Psychology, University of Pennsylvania, Philadelphia, PA.  We thank David Hoffman for assistance with this work. Download PDF. Code related to this report is available at

Radonjic, A., Cottaris N.P., and Brainard, DH. (2015) “Color constancy in a naturalistic goal-directed task”, J. of Vision, In Press

Cottaris, N.P.  (2011) RFspotter iPad app.  On-line information.  Available on iTunes.

Cottaris, N.P. and Elfar, S.D (2009). Assessing the efficacy of visual prosthesis by decoding ms-LFPs: application to retinal implants. Journal of Neural Engineering, 6, 026007. Selected for inclusion to IOP-select due to the paper’s novelty and potential impact on future research. Download PDF.

Elfar, S.D. and Cottaris, N.P. (2009). A cortical (V1) neurophysiological recording model for asessing the efficacy of retinal visual prostheses. Journal of Neuroscience Methods, 180, 195-207. Download PDF.

Cottaris, N.P. and Elfar, S.D (2005). How the retinal network reacts to epiretinal stimulation to form the prosthetic visual input to the cortex. Journal of Neural Engineering, 2, S74-90. Download PDF.

Cottaris, N.P. (2003). Artifacts in spatiochromatic stimuli due to variations in preretinal absorption and axial chromatic aberration: Implications for color physiology, Journal of the Optical Society of America, A, 20, 1694-1713. Download PDF.

De Valois, R.L., Cottaris, N.P.,  Mahon, L. ,  Elfar, S.D., and  Wilson, A.J. (2000). Spatial and temporal phases of geniculate and cortical cells and directional selectivity, Vision Research, 40, 3685-3702. Download PDF.

De Valois, R.L., and Cottaris, N.P. (1998). Inputs to directionally-selective simple cells in macaque primary visual cortex. Proceedings of the National Academy of Sciences USA, 95, 14488-14493. Download PDF.

Cottaris, N.P., and De Valois, R.L. (1998). Temporal dynamics of  chromatic tuning in macaque primary visual cortex. Nature, 395, 896-900.   Download PDF.  News & Views commentary by Robert Shapley.

Courses Taught

  • Optics I, II (Graduate Student Instructor, U.C. Berkeley)
  • Computer Applications in Biomedical Engineering (Teaching Assistant, Rutgers U.)
  • Neuro-Electric Systems (Teaching Assistant, Rutgers U.)


  • Computational Neuroscience Initiative
  • Department of Psychology