A 35μW 64 × 64 Pixels Vision Sensor Embedding Local Binary Pattern Code Computation

Abstract

This paper presents a 64 × 64 pixels vision sensor embedding pixel-wise computation of the Local Binary Pattern (LBP) code, which is an oriented, binary, vector contrast that is widely used for texture description and retrieval. For each pixel, the sensor estimates the LBP code over four neighbors in a 3×3 pixel kernel. The image processing is performed inside each pixel during the integration time over a dynamic range up to 98dB, thanks to a pixel-level auto-exposure control. The contrast detection relies on the estimation of the time difference between two pixels thresholded against two reference voltages. The four binary signed contrast vectors are delivered to the output, coded into 4-bit/pixel. The 0.35μm CMOS sensor features a power consumption of 35μW at 3.3V and 15fps.