1D Cellular Automata for Pulse Width Modulated Compressive Sampling CMOS Image Sensors

Compressive sensing (CS) is an alternative to the Shannon limit when the signal to be acquired is known to be sparse or compressible in some domain. Since compressed samples are non-hierarchical packages of information, this acquisition technique can be employed to overcome channel losses and restricted data rates. The quality of the compressed samples that a sensor can deliver is affected by the measurement matrix used to collect them. Measurement matrices usually employed in CS image sensors are recursive random-like binary matrices obtained using pseudo-random number generators (PRNG). In this paper we analyse the performance of these PRNGs in order to understand how their non-idealities affect the quality of the compressed samples. We present the architecture of a CMOS image sensor that uses class-III elementary cellular automata (ECA) and pixel pulse width modulation (PWM) to generate onchip a measurement matrix and high the quality compressed samples.Ministerio de Economía y Competitividad TEC2015-66878-C3-1-RJunta de Andalucía TIC 2338-2013Office of Naval Research N000141410355CONACYT (Mexico) MZO-2017-29106

Concurrent focal-plane generation of compressed samples fromtime-encoded pixel values

Compressive sampling allows wrapping the relevant content of an image in a reduced set of data. It exploits the sparsity of natural images. This principle can be employed to deliver images over a network under a restricted data rate and still receive enough meaningful information. An efficient implementation of this principle lies in the generation of the compressed samples right at the imager. Otherwise, i. e. digitizing the complete image and then composing the compressed samples in the digital plane, the required memory and processing resources can seriously compromise the budget of an autonomous camera node. In this paper we present the design of a pixel architecture that encodes light intensity into time, followed by a global strategy to pseudo-randomly combine pixel values and generate, on-chip and on-line, the compressed samples.Ministerio de Economía y Competitividad TEC 2015-66878-C3-1-RJunta de Andalucía TIC 2338-2013Office of Naval Research (USA) N000141410355CONACYT (Mexico) MZO-2017-29106