Tetsuya Yagi

Learn More
In this paper, we designed and fabricated a multichip neuromorphic analog very large scale integrated (aVLSI) system, which emulates the orientation selective response of the simple cell in the primary visual cortex. The system consists of a silicon retina and an orientation chip. An image, which is filtered by a concentric center-surround (CS) antagonistic(More)
A silicon retina that emulates the sustained and the transient responses in the vertebrate retina was fabricated. The circuit of the chip consists of two layers of resistive network that have different length constants. The output emulating the sustained response possesses a Laplacian-Gaussian-like receptive field and, therefore, carries out a smoothing and(More)
The horizontal cell is a second-order retinal neuron that is depolarized in the dark and responds to light with graded potential changes. In such a nonspiking neuron, not only the voltage-gated ionic conductances but also Ca(2+) regulation mechanisms, e.g., the Na(+)/Ca(2+) exchange and the Ca(2+) pump, are considered to play important roles in generating(More)
Layered architecture is proposed for solving a class of regularization problems in image processing. There are two major hurdles in the implementation of regularization filters with second or higher order smoothness constraints: (a) Stability: With second or higher order constraints, a direct implementation of a regularization filter necessitates negative(More)
We designed a VLSI binocular vision system that emulates the disparity computation in the primary visual cortex (V1). The system consists of two silicon retinas, orientation chips, and field programmable gate array (FPGA), mimicking a hierarchical architecture of visual information processing in the disparity energy model. The silicon retinas emulate a(More)
— We describe a binocular vision system that emulates disparity computation in the neuronal circuit of the primary visual cortex (V1). The system consists of two sets of silicon retinas and simple cell chips that correspond to the binocular vision and field programmable gate array (FPGA) circuit. This arrangement mimics the hierarchical architecture of the(More)
— A real-time vision sensor for collision avoidance was designed. To respond selectively to approaching objects on direct collision course, the sensor employs an algorithm inspired by the visual nervous system in a locust, which can avoid a collision robustly by using visual information. We implemented the architecture of the locust nervous system with a(More)
The neuromorphic silicon retina is a novel analog very large scale integrated circuit that emulates the structure and the function of the retinal neuronal circuit. We fabricated a neuromorphic silicon retina, in which sample/hold circuits were embedded to generate fluctuation-suppressed outputs in the previous study [1]. The applications of this silicon(More)
Light-adaptive algorithms~architectures are proposed for regularization vision chips. The adaptation mechanisms allow the regularization parameters to change in an adaptive manner in accordance with the light intensity of given images. This is achieved by adaptively changing the conductance values associated with massively parallel resistive networks. The(More)