Computational periscopy with an ordinary digital camera

Computing the amounts of light arriving from different directions enables a diffusely reflecting surface to play the part of a mirror in a periscope—that is, perform non-line-of-sight imaging around an obstruction. Because computational periscopy has so far depended on light-travel distances being proportional to the times of flight, it has mostly been performed with expensive, specialized ultrafast optical systems^1,2,3,4,5,6,7,8,9,10,11,12. Here we introduce a two-dimensional computational periscopy technique that requires only a single photograph captured with an ordinary digital camera. Our technique recovers the position of an opaque object and the scene behind (but not completely obscured by) the object, when both the object and scene are outside the line of sight of the camera, without requiring controlled or time-varying illumination. Such recovery is based on the visible penumbra of the opaque object having a linear dependence on the hidden scene that can be modelled through ray optics. Non-line-of-sight imaging using inexpensive, ubiquitous equipment may have considerable value in monitoring hazardous environments, navigation and detecting hidden adversaries.We thank F. Durand, W. T. Freeman, Y. Ma, J. Rapp, J. H. Shapiro, A. Torralba, F. N. C. Wong and G. W. Wornell for discussions. This work was supported by the Defense Advanced Research Projects Agency (DARPA) REVEAL Program contract number HR0011-16-C-0030. (HR0011-16-C-0030 - Defense Advanced Research Projects Agency (DARPA) REVEAL Program)Accepted manuscrip

Optimal stopping times for estimating Bernoulli parameters with applications to active imaging

We address the problem of estimating the parameter of a Bernoulli process. This arises in many applications, including photon-efficient active imaging where each illumination period is regarded as a single Bernoulli trial. We introduce a framework within which to minimize the mean-squared error (MSE) subject to an upper bound on the mean number of trials. This optimization has several simple and intuitive properties when the Bernoulli parameter has a beta prior. In addition, by exploiting typical spatial correlation using total variation regularization, we extend the developed framework to a rectangular array of Bernoulli processes representing the pixels in a natural scene. In simulations inspired by realistic active imaging scenarios, we demonstrate a 4.26 dB reduction in MSE due to the adaptive acquisition, as an average over many independent experiments and invariant to a factor of 3.4 variation in trial budget.Accepted manuscrip

Source shot noise mitigation in scanned beam microscopy

Accepted manuscrip

Beyond Binomial and Negative Binomial: Adaptation in Bernoulli Parameter Estimation

Estimating the parameter of a Bernoulli process arises in many applications, including photon-efficient active imaging where each illumination period is regarded as a single Bernoulli trial. Motivated by acquisition efficiency when multiple Bernoulli processes are of interest, we formulate the allocation of trials under a constraint on the mean as an optimal resource allocation problem. An oracle-aided trial allocation demonstrates that there can be a significant advantage from varying the allocation for different processes and inspires a simple trial allocation gain quantity. Motivated by realizing this gain without an oracle, we present a trellis-based framework for representing and optimizing stopping rules. Considering the convenient case of Beta priors, three implementable stopping rules with similar performances are explored, and the simplest of these is shown to asymptotically achieve the oracle-aided trial allocation. These approaches are further extended to estimating functions of a Bernoulli parameter. In simulations inspired by realistic active imaging scenarios, we demonstrate significant mean-squared error improvements: up to 4.36 dB for the estimation of p and up to 1.80 dB for the estimation of log p.Comment: 13 pages, 16 figure

Prospectus, October 2, 1970

GRADING SYSTEM HAS N\u27S AND I\u27S; New Policies Started For Parkland College; S.W.A.M.P. Fights Pollution, Apathy; Some Things To Come; Pollution-Sollution?: A Personal Challenge; Student Conduct Rules; Bull Page: News Shorts, New Teachers, Community Theatre 1970-1971 Season, Upcoming Movies, Charley Chan; Parkland College Golf Schedule 1970-71; Cheerleading Tryouts; Linksmen Open Fall Season; Intramurals Starthttps://spark.parkland.edu/prospectus_1970/1026/thumbnail.jp

Prospectus, October 16, 1970

PARKLAND WELCOMES NEW COUNSELORS; Letters to Editor; Oops!; Pollution-Solutions?: Real Of Objectivity; Comments: War And Peace; Bull Page: Movie Revue Joe, Decision Making, Conveniamus, Campus Organizations, Vets Meeting, Discussion Group, IOC, Movie, U.N. Week, Phi Gamma IOTA, Mailboxes, Wit N\u27 Wisdom, Mailboxes; Yes Sir -- I\u27m For Real: Illini Nips PC 7-6 In Defensive Battle; Coaches Corner; Six Man Flag Footballhttps://spark.parkland.edu/prospectus_1970/1024/thumbnail.jp

Prospectus, February 5, 1971

FAMOUS ENVIRONMENTALIST COMING TO PARKLAND; Student Government Cited As Progressive ; Teacher Works For ZPG; Problems Of Our Times: Laisse-Faireism; Letters To Editor; Comments On Letters; Bull Page: Upcoming Events, SWAMP, Library Cards, News Release, Wit N\u27 Wisdom, Family Night, Vets Meeting, Play Tryouts, Teach In, Gemini House, Yearbook Pictures, IOC, SASLA, Fail Safe, Flash Gordon, Hotline; Rich Harper explodes for 23: Eastern Frosh Defeat Cobras; Penthouse Gang Clinches Tie; College Swim Meet February 10, 4:00 p.m.; Parkland Places Third in Tourney; Joliet Community Beats Cobras; Intramural Standings; Campbell Recruite From Decaturhttps://spark.parkland.edu/prospectus_1971/1013/thumbnail.jp

Time-resolved focused ion beam microscopy: modeling, estimation methods, and analyses

In a focused ion beam (FIB) microscope, source particles interact with a small volume of a sample to generate secondary electrons that are detected, pixel by pixel, to produce a micrograph. Randomness of the number of incident particles causes excess variation in the micrograph, beyond the variation in the underlying particle-sample interaction. We recently demonstrated that joint processing of multiple time-resolved measurements from a single pixel can mitigate this effect of source shot noise in helium ion microscopy. This paper is focused on establishing a rigorous framework for understanding the potential for this approach. It introduces idealized continuous- and discrete-time abstractions of FIB microscopy with direct electron detection and estimation-theoretic limits of imaging performance under these measurement models. Novel estimators for use with continuous-time measurements are introduced and analyzed, and estimators for use with discrete-time measurements are analyzed and shown to approach their continuous-time counterparts as time resolution is increased. Simulated FIB microscopy results are consistent with theoretical analyses and demonstrate that substantial improvements over conventional FIB microscopy image formation are made possible by time-resolved measurement.First author draf