High dynamic range adaptation for ROI tracking based on reconfigurable concurrent dual-sensing

A single-exposure technique to extend the dynamic range of vision sensors is presented. It is particularly suitable for vision algorithms requiring region-of-interest (ROI) tracking under varying illumination conditions. The operation is supported by two intertwined photo-diodes at pixel level and two digital registers at the periphery of the pixel matrix. These registers divide the focal plane into independent regions within which automatic concurrent adjustment of the integration time takes place for each frame. At pixel level, one of the photodiodes senses the pixel value itself, whereas the other, in collaboration with its counterparts in every prescribed ROI, senses the mean illumination of that specific ROI. An additional circuitry interconnecting both photodiodes asynchronously determines the integration period for each ROI according to its mean illumination. The experimental results for a quarter video graphics array prototype CMOS vision sensor are reported.