Departmental Papers (ESE)


A compact CMOS vision sensor for the detection of higher level image features, such as corners, junctions (T-, X-, Y-type) and linestops, is presented. The on-chip detection of these features significantly reduces the data amount and hence facilitates the subsequent processing of pattern recognition. The sensor performs a series of template matching operations in an analog/digital mixed mode for various kinds of image filtering operations including thinning, orientation decomposition, error correction, set operations, and others. The analog operations are done in the current domain. A design procedure, based on the formulation of the transistor mismatch, is applied to fulfill both accuracy and speed requirements. The architecture resembles a CNN-UM that can be programmed by a 30-bit word. The results of an experimental 16x16 pixel chip demonstrate that the sensor is able to detect features at high speed due to the pixel-parallel operation. Over 270 individual processing operations are performed in about 54 µsec.

Document Type

Journal Article

Date of this Version

December 2005


Postprint version. Published in Analog Integrated Circuits and Signal Processing, Volume 45, Issue 3, December 2005, pages 263-279. The original publication is available at
Publisher URL:


feature detection, vision sensor, smart sensor, computational sensor, template-matching, transistor mismatch



Date Posted: 02 August 2006

This document has been peer reviewed.