Photon Shot Research Articles

An improved raw image enhancement algorithm using a statistical model for pixel value error

When an image is captured using an electronic sensor, statistical variations introduced by photon shot and other noise introduce errors in the raw value reported for each pixel sample. Earlier work found that modest improvements in raw image data quality reliably could be obtained by using empirically-determined pixel value error bounds to constrain texture synthesis. However, the prototype software implementation, KREMY (KentuckY Raw Error Modeler, pronounced “creamy”), was not effective in processing very noisy images. In comparison, the current work has reimplemented KREMY to make it capable of credibly improving far noisier raw DNG images. The key is a new approach that uses a simpler, but statistical, model for pixel value errors rather than simple bounds constraints.

Refining raw pixel values using a value error model to drive texture synthesis

The goal in photography is generally the construction of a model of scene appearance. Unfortunately, statistical variations introduced by photon shot and other noise introduce errors in the raw value reported for each pixel sample. Rather than simply accepting those values as the best raw representation, the current work treats them as initial estimates of the correct values, and computes an error model for each pixel's value. The value error models for all pixels in an image are then used to drive a type of texture synthesis which refines the pixel value estimates, potentially increasing both accuracy and precision of each value. Each refined raw pixel value is synthesized from the value estimates of a plurality of pixels with overlapping error bounds and similar context within the same image. The error modeling and texture synthesis algorithms are implemented in and evaluated using KREMY (KentuckY Raw Error Modeler, pronounced "creamy"), a free software tool created for this purpose.

Photon and phonon-assisted shot noise in a molecular quantum-dot-ferromagnetic system in the Coulomb blockade regime

The dynamic shot noise in a molecular quantum dot connected to two non-collinear ferromagnetic terminals under the perturbation of ac fields has been investigated by the nonequilibrium Green’s function approach. The formulas of current, current correlation, and shot noise have been presented in the weak electron-phonon (el-ph) interaction regime to address the cooperated behaviors generated by the photon and phonon perturbation. The photon and phonon perturbations induce quite different current correlations, and the noise suppression occurs unambiguously by increasing the phonon energy in the valley regime. The suppression of shot noise comes from drawing the unbalanced current correlation towards the balanced one, where coherent current correlation takes major role. The suppression of photon-assisted shot noise can be completed mainly by rotating polarization angle of the terminals, and increasing the phonon energy ħω 0. The Fano factor is enhanced considerably by the el-ph interaction, and it is also enhanced by increasing the polarization angle from θ = 0 to θ = π.

Detection of Laser Radiation*

A generalized representation of the radiation field incident on the photosensitive surface of a photoelectric device accommodates the consideration of many laser beams superposed or the consideration of radiation due to multimodes or multiple filaments of a single laser. The magnitudes and frequencies of the fluctuations in electron emission from the photosurface associated with photon noise and shot noise and the parameters affecting these magnitudes are determined. Also, the influence of these fluctuations on the probability of detecting low-level laser radiation is investigated.