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Department of Computer Science and Technology

Thursday, 21 March, 2024 - 14:00 to 15:00
Prof. Thomas S. A. Wallis, Technical University of Darmstadt
SS03 - William Gates Building

The human visual system compresses the information about the world implicit in the light entering our eyes. Decades of research in vision science has provided good hypotheses for the features that are encoded by the early visual system and made available for cognition and action. One approach to testing these hypotheses uses analysis by synthesis: one can generate artificial image stimuli that should differentiate competing encoding accounts, or for which an encoding account makes a strong prediction about discriminability. A classical example from vision is colour metamerism. Two spectrally-distinct surfaces will appear to be the same colour as long as the ratios of cone activations are identical (and context is comparable). I will present work extending this concept to the discriminability of photographic scenes. I will show examples from past work in which we used this logic to psychophysically test a popular analogy for vision in the periphery, as that of a "texture-like" representation. We find two extant models fail to adequately capture image discriminability, and we speculate about what ingredients might be missing. Ongoing work extends this using a data-driven approach, and expands to test other models. Overall, classical psychophysical methods combined with hypotheses from vision science and modern tools in image synthesis provide a powerful approach to test the functional encoding of visual information.

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