We present a simple and usable noise model for the raw-data of digital imaging sensors This signal-dependent noise model, which gives the pointwise standard-deviation of the noise as a function of the expectation of the pixel raw-data output, is composed of a Poissonian part, modeling the photon sensing, and Gaussian part, for the remaining stationary disturbances in the output data We further explicitly take into account the clipping of the data (over- and under-exposure), faithfully reproducing the nonlinear response of the sensor We propose an algorithm for the fully automatic estimation of the model parameters given a single noisy image Experiments with synthetic images and with real raw-data from various sensors prove the practical applicability of the method and the accuracy of the proposed model

/pdf/practical-poissonian-gaussian-noise-modeling-and-fitting-for-4cn04dppj4.pdf

Practical Poissonian-Gaussian Noise Modeling and Fitting for Single-Image Raw-Data

http://www.intelligence.tuc.gr/~petrakis/publications/mape02.pdf

A survey on industrial vision systems, applications and tools

An experimental technique is described for observing the effects of switching transients in digital MOS circuits that perturb analog circuits integrated on the same die by means of coupling through the substrate Various approaches to reducing substrate crosstalk (the use of physical separation of analog and digital circuits, guard rings, and a low-inductance substrate bias) are evaluated experimentally for a CMOS technology with a substrate comprising an epitaxial layer grown on a heavily doped bulk wafer Observations indicate that reducing the inductance in the substrate bias is the most effective Device simulations are used to show how crosstalk propagates via the heavily doped bulk and to predict the nature of substrate crosstalk in CMOS technologies integrated in uniform, lightly doped bulk substrates, showing that in such cases the substrate noise is highly dependent on layout geometry A method of including substrate effects in SPICE simulations for circuits fabricated on epitaxial, heavily doped substrates is developed >

Experimental Results and Modeling Techniques for Substrate Noise in Mixed-Signal Integrated Circuits

This paper is a review of methods and techniques used for precise measurement of time intervals (TIs) or precise conversion of TIs to digital data. The following methods are described: the counter method and averaging, time stretching, time-to-amplitude conversion followed by analogue-to-digital conversion, the Vernier method, conversion utilizing tapped delay lines, and interpolation methods. Special attention has been paid to converters utilizing integrated delay lines for digital conversion of TIs, including designs with phase-locked loop and delay-locked loop circuits. This review is illustrated by design examples and contains a comprehensive list of references.

https://iopscience.iop.org/article/10.1088/0026-1394/41/1/004/pdf

Review of methods for time interval measurements with picosecond resolution

A passive touch system includes a passive touch surface and at least two cameras associated with the touch surface. The at least two cameras acquire images of the touch surface from different locations and have overlapping fields of view. A processor receives and processes images acquired by the at least two cameras to detect the existence of a pointer therein and to determine the location of the pointer relative to the touch surface. Actual pointer contact with the touch surface and pointer hover above the touch surface can be determined.

Passive touch system and method of detecting user input

An experimental technique is described for observing the effects of switching transients in digital MOS circuits that perturb analog circuits integrated on the same die by means of coupling through the substrate. Various approaches to reducing substrate crosstalk (the use of physical separation of analog and digital circuits, guard rings, and a low-inductance substrate bias) are evaluated experimentally for a CMOS technology with a substrate comprising an epitaxial layer grown on a heavily doped bulk wafer. Observations indicate that reducing the inductance in the substrate bias is the most effective. Device simulations are used to show how crosstalk propagates via the heavily doped bulk and to predict the nature of substrate crosstalk in CMOS technologies integrated in uniform, lightly doped bulk substrates, showing that in such cases the substrate noise is highly dependent on layout geometry. A method of including substrate effects in SPICE simulations for circuits fabricated on epitaxial, heavily doped substrates is developed. >

Experimental results and modeling techniques for substrate noise in mixed-signal integrated circuits

The performance of a color CMOS photogate image sensor is reported. It is shown that by using two levels of correlated-double sampling it is possible to effectively cancel all fixed-pattern noise due to read-out circuit mismatch. Instead the fixed-pattern noise performance of the sensor is limited by dark current nonuniformity at low signal levels, and conversion gain nonuniformity at high signal levels. It is further shown that the imaging performance of the sensor is comparable to low-end CCD sensors but inferior to that reported for high-end CCD sensors due to low quantum efficiency, high dark current, and pixel cross-talk. As such the performance of CMOS sensors is limited at the device level rather than at the architectural level. If the imaging performance issues can be addressed at the fabrication process level without increasing cost or degrading transistor performance, CMOS has the potential to seriously challenge CCD as the solid-state imaging technology of choice due to low power dissipation and compatibility with camera system integration.

Performance analysis of a color CMOS photogate image sensor

A digital color camera has been monolithically realized in a standard 0.8-/spl mu/m CMOS technology. The chip integrates a 353/spl times/292 photogate sensor array with a unity-gain column circuit, a hierarchical column multiplexer, a switched-capacitor programmable-gain amplifier, and an 8-b flash analog/digital converter together with digital circuits performing color interpolation, color correction, computation of image statistics, and control functions. The 105-mm/sup 2/ chip produces 24-b RGB video at 30 frames/s. The sensor array achieves a conversion gain of 40 /spl mu/V/electron and a monochrome sensitivity of 7 V/lux/spl middot/s. For a 33-ms exposure time, the camera chip achieves a dynamic range of 65 dB and peak-to-peak fixed pattern noise that is 0.3% of saturation. Digital switching noise coupling into the analog circuits is shown to be data independent and therefore has no effect on image quality. Total power dissipation is less than 200 mW from a 3.3 V supply.

A 200 mW 3.3 V CMOS color camera IC producing 352/spl times/288 24 b video at 30 frames/s

A single slope A/D converter utilizes a sub-nanosecond time digitizer to achieve increased conversion rates independent of a high frequency clock, and so is capable of being implemented in diverse applications. High conversion rates ranging from about 3 MHz to about 12 MHz and higher may be implemented on integrated circuits without using a high frequency clock.

Marc J. Loinaz

Papers

Experimental results and modeling techniques for substrate noise in mixed-signal integrated circuits

Experimental Results and Modeling Techniques for Substrate Noise in Mixed-Signal Integrated Circuits

Performance analysis of a color CMOS photogate image sensor

A 200 mW 3.3 V CMOS color camera IC producing 352/spl times/288 24 b video at 30 frames/s

Analog-to-digital converter having voltage to-time converter and time digitizer, and method for using same