Sophie Wuerger

Abstract: The response of the human visual system depends on a multitude of image features, such as the wavelength (color) of the visual stimulus and its spatial frequency content. This talk reviews current models of color appearance, in particular unique hues as a tool to measure appearance and its potential applications. It then discusses how color is always associated with a spatial component, and how the chromatic and spatial information is encoded simultaneously, most likely in the same neurones. A review of experimental evidence on spatio-chromatic processing consistent with this idea is presented, and recent experiments on spatio-chromatic contrast sensitivity assessed on HDR displays is also discussed.

Professor Sophie Wuerger is interested in understanding how the brain processes visual information, in particular how the signals from the eye map into high-order color appearance mechanisms. To gain an understanding of the neural visual mechanisms she uses behavioural methods, EEG, and functional brain imaging. Her work has both clinical and technological application, including display calibration and the development of computational appearance models.

Abstract: The color of ocean water provides us tremendous insights regarding the properties of the particles in it. For example using satellites that sense ocean color, we are able to monitor worldwide concentration of phytoplankton—tiny organisms in the water column that produce food for everything else in the ocean to eat. That ocean water has color, however, is precisely what is holding us back from unveiling the colors of everything else, i.e., the colors of the ocean flora, fauna, and the unique habitats that host them. Why does anything in the ocean have color, if that color is to be masked by the color of the water? What would we learn if we could survey the true colors of everything in the ocean?

Derya Akkaynak is an engineer and oceanographer whose research focuses on problems of imaging and vision underwater. She has professional, technical, and scientific diving certifications and has conducted fieldwork from the Bering Sea to Antarctica. Akkaynak is an honoree for the 2019 Blavatnik Awards for Young Scientists in physics & engineering for resolving a fundamental problem in underwater computer vision—the reconstruction of lost colors and contrast. She works at Harbor Branch Oceanographic Institute in Florida.

Abstract: Most digital cameras in use today measure color through spatial multiplexing: interestingly, still relying on the Bayer pattern from the 1970s. In this talk, Chakrabarti describes new approaches to thinking about digital color sensors and reconstruction algorithms, borrowing ideas from those that have been successful in related computer vision algorithms. The talk begins by describing a sensor design and reconstruction method based on sparse color measurement, which draws inspiration from "interactive colorization" algorithms that are able to convert black and white images to color from a few color strokes as annotation. Then,Chakrabarti argues for a more data-driven way for jointly designing sensors and computational reconstruction algorithms. In this spirit, the talk explains an automated way to "learn" the right multiplexed color measurement strategy, by treating the color sensor as a "layer" in a neural network. Experimental results will show the benefits of both approaches, and interestingly, that the learning-based approach is able to automatically discover a sparse measurement strategy as being optimal. The talk ends with a discussion on how data-driven sensor design can be a useful tool when building cameras for applications beyond reconstruction.

Ayan Chakrabarti is an assistant professor at Washington University in St. Louis, where he directs the vision and learning group. He works on problems in machine learning, computer vision, and computational photography: dealing with the design of accurate and efficient visual inference algorithms, and of new kinds of high-capability sensors and cameras. He received his PhD (2011) from Harvard University working with Todd Zickler, and was previously research faculty at TTIC.