Devolopment of a parallel analog vision chip for early vision

视觉芯片是一种新型的图像处理系统，其设计采用模拟CMOS非常大规模集成（VLSI）电路技术，灵感来自视网膜的结构和功能。由于投影在芯片上的图像是利用VLSI电路的动态特性并行处理的，因此该芯片有望在实时图像处理方面突破传统数字图像处理系统的致命缺点。本课题的目的是设计一种模拟视网膜双极细胞网络功能和结构的视觉芯片。以下是我们1994-1995年所得结果的摘要。建立了视网膜双极细胞的电阻网络模型，并对其功能进行了定量研究。该电路被发现可以再现视网膜双极细胞的响应特性，例如对图像进行平滑和对比度增强操作。利用该模型，根据早期视觉的标准正则化理论，建立了视网膜双极细胞网络的功能。设计了该模型的模拟VLSI电路，并利用PSPICE.4仿真软件对电路的性能进行了分析。以该模型为灵感，通过mosis制作了视觉芯片。在此基础上，我们进一步研究了双极细胞网络的时间特性。该模型被发现可以解释视网膜双极细胞反应的时间特性。

The vision chip is a novel image processing system, which is designed using analog CMOS Very Large Scale Integrated (VLSI) circuit technology, inspired by structures and functions of the retina. Since images projected on the chip are processed in parallel by dynamical properties of the VLSI circuit, the chip is expected to give a breakthrough to fatal disadvantages of conventional digital image processing systems in the real-time image processing. The purpose of this project is to design a vision chip which mimics functions and structures of the retinal bipolar cell network. The followings are the summary of results we obtained in 1994-1995.1.A resistive network model of the retinal bipolar cell was developed and the functions of the network were studied quantitatively. The circuit was found to reproduce the response properties of the retinal bipolar cell, e.g., smooting and contrast enhancement operations on images.2.Using the model, the function of retinal bipolar cell network was formulated in terms of the standard regularization theory of early vision.3.An analog VLSI circuit of the model was designed and performances of the circuit were analyzed with the simulation software PSPICE.4.A vision chip inspired by the model was fabricated through the MOSIS.5.We further studied temporal properties of bipolar cell network by incorporating dynamical elements in above model. The model was found to explaine the temporal properties of retinal bipolar cell response.