Izumi Ohzawa: “What features are matched binocularly for stereopsis?”
12:15 〜 13:00
CiNet 1F Conference Room
Graduate School of Frontier Biosciences
Host PI : Izumi Ohzawa
There is a recent surge of interest in deep-learning neural nets. A typical configuration of such neural nets is a hierachical repetition of layers consisting of filtering and pooling. We have studied theoretically and experimentally, the effects of pooling on neural representation of stereoscopic depth information.
The key problem of stereoscopic vision is traditionally defined as accurately finding the positional shifts of corresponding object features between left and right images. Here, we demonstrate that the problem must be considered in a four-dimensional parameter space; with respect not only to shifts in space (X, Y), but also spatial frequency (SF) and orientation (OR). The proposed model sums outputs of binocular energy units linearly over the multi-dimensional V1 parameter space (X, Y, SF, OR) as illustrated in the figure.
Monocularly, pooling generally causes loss of information about visual detail, since it is similar to defocus in a camera, in exchange for reduction of noise and gain in robustness.
Binocularly, however, the same pooling produces completely oppsite effects. Pooling sharpens tuning for left-right stimulus matches in all of the V1 parameter domains.
Our research demonstrates theoretically and experimentally that the pooling has the capacity to generate a more precise representation of stereoscopic information. Our finding has a potential to improve accuracy and robustness of stereovision applicatons.
Kato D, Baba M, Sasaki KS, Ohzawa I.
Effects of generalized pooling on binocular disparity selectivity of neurons in the early visual cortex.
Phil. Trans. R. Soc. B 371: 20150266. (2016)
The Friday Lunch Seminar is CiNet's main regular meeting series, held every week at 12:15 in the beautiful main lecture theatre on the ground floor at CiNet. The talks are typically 40mins long and orientated towards an inter-disciplinary audience. They are informal, social, and most people bring their own lunch to eat during the talk. They are open to anyone who is feeling curious and wants to come, regardless of where you work.