Quantum of Vision

All rights reserved iii ACKNOWLEDGEMENTS I enjoy doing research that is different. Being different means not inheriting the definitions and solutions of existing problems but striving to recognize and address new problems. This notion of being different is imparted to me by my advisor Prof. Pietro Perona, to whom I am deeply grateful. I have consulted Pietro for basically everything: the meaning of life, the purpose of research, strategies for picking research projects, strategies for picking engagement rings, the best wedding venues, and the best obstetricians. Thank you, Pietro, for being the walking embodiment of Google and what Google could only aspire to become. I would also like to express my heartfelt gratitude towards Prof. Ueli Rutishauser and Dr. Qi Zhao for indulging my interdisciplinary wanderlust, as well as Dr. Lubomir Bourdev and Dr. Yang Song for connecting my research with practice. Furthermore, my sincere appreciation goes to my thesis committee, including Prof. who have become an integral part of my scholarly upbringing. I will also miss the thoughtful dinner conversations with Dr. Being different also comes with a cost, as the road less traveled is often traveled alone. The past six years have been an uphill battle where I have constantly been on the losing side. The intellectual solitude was bearable owing to the social companionship of my dear family and friends. I am blessed with the great friend Linsanity Yongjun, who was always there when I needed a morale boost. I am indebted to all members of the Vision lab for their moral support, with a special hat tip to Krzysztof Chalupka, Matteo Ruggero Ronchi and Joe Marino for going out of their way to ensure my wellbeing. Dr. Tatiana Vasilevskaia and the Caltech counseling center were also tremendously helpful. Just as this thesis will discuss how vision systems can see in the dark with only a few particles of light, I saw the way forward in my darkest moments thanks to the small glimpses of hope: every kind word and every pat on the shoulder brought me closer to the finishing line. The brightest beacon of hope was my wife Kaida, who supported my journey with unconditional optimism, unique perspectives and unquestionably exquisite culinary skills, and to whom I wholeheartedly devote this thesis. iv ABSTRACT Visual inputs to artificial and biological visual systems are often quantized: cameras accumulate photons from the visual world, and the brain receives …