Navigating the roadblocks to spectral color reproduction: data-efficient multi-channel imaging and spectral color management

Commercialization of spectral imaging for color reproduction will require the identification and traversal of roadblocks to its success. Among the drawbacks associated with spectral reproduction is a tremendous increase in data capture bandwidth and processing throughput. Methods are proposed for attenuating these increases with data-efficient methods based on adaptive multi-channel visible-spectrum capture and with low-dimensional approaches to spectral color management. First, concepts of adaptive spectral capture are explored. Current spectral imaging approaches require tens of camera channels although previous research has shown that five to nine channels can be sufficient for scenes limited to pre-characterized spectra. New camera systems are proposed and evaluated that incorporate adaptive features reducing capture demands to a similar few channels with the advantage that a priori information about expected scenes is not needed at the time of system design. Second, proposals are made to address problems arising from the significant increase in dimensionality within the image processing stage of a spectral image workflow. An Interim Connection Space (ICS) is proposed as a reduced dimensionality bottleneck in the processing workflow allowing support of spectral color management. In combination these investigations into data-efficient approaches improve two critical points in the spectral reproduction workflow: capture and processing. The progress reported here should help the color reproduction community appreciate that the route to data-efficient multi-channel visible spectrum imaging is passable and can be considered for many imaging modalities

An Uncertainty analysis of a color tolerance database

A database designed to develop, evaluate and compare color-difference formulae, particularly for use within the suprathreshold industrial-sized range, so named for its importance in many commercial transactions, has been under development at the Munsell Color Science Laboratory. The database consists of two independent data sets, previously published. The sets and the experimental conditions under which they were derived were analyzed to determine the appropriateness of pooling the data. The earlier of the two studies had associated statistics which indicated a population of highly precise observers. The latter study\u27s population displayed a significantly greater level of uncertainty. The current work concluded that the increase in observer imprecision was a consequence of increased task difficulty. A median filtering of raw individual observer responses improved interpretability of the data and enabled pooling of the sets. The pooled results were compared with various widely used color-difference formulae of which CMC(1:1) had the highest correlation

Lippman 2000: a spectral image database under construction

In support of research projects both within the Munsell Color Science Laboratory and outside which rely on having full knowledge of the spectral makeup of scenes, a number of methods for capturing spectral images are being explored. This project is named Lippmann2000 in honor of Gabriel Lippmann who in 1891 devised a method to perfectly reconstruct the spectral content of real world scenes. In spite of Lippmann’s invention, a more primitive three-channel model, first demonstrated by James Clerk Maxwell 30 years prior, has dominated the color imaging field. The Maxwellian model, universal in today’s silver halide and electronic color image capture systems, relies on the metameric properties of the human visual system to simulate the appearance of an original color. It has been recognized by those in the forefront of imaging research that the capture of full spectral data holds advantage over traditional three-channel methods. This paper describes our efforts to-date to build our database of spectral images

Data-efficient methods applied to general spectral image capture

Commercialization of spectral imaging for color reproduction will require low bandwidth but highly accurate spectral image acquisition systems. Self-adapting systems are proposed as potential solutions. Such systems perform spectral content analysis on an encountered scene, reacting to the analysis by configuring efficient high quality spectral reconstruction. An experiment is reported comparing scene-derived spectral estimation transforms to static global transforms in multi-channel imaging simulations. For noisefree simulations, the adaptive approach showed clear benefit in terms of colorimetric and spectral statistics. When noise was added, the adaptive method continued to be superior in terms of spectral evaluations, but colorimetric degradation for the adaptive approach exceeded that of the static. This provided additional evidence that spectral reconstruction methods should reference psychometrics as an integral part of spectral error management

Analysis of hybrid satellite-to-satellite tracking and quantum gravity gradiometry architecture for time-variable gravity sensing missions

The Gravity Recovery and Climate Experiment (GRACE) mission, its follow on (GRACE-FO) and the Gravity-field and steady-state Ocean Circulation Experiment (GOCE) mission have been key contributors to the advancement of the study of Earth's gravity field in the 21st century. The gravity gradiometers on GOCE are limited in their sensitivity and are therefore limited to studying the Earth's static gravity field. However, recent advancements in atomic interferometry have increased the feasibility of implementing this technology to the study of time-variable aspects of the Earth's gravity field, as with the GRACE satellite-to-satellite tracking technology. It is anticipated that these measurement types will provide information about the time-variable gravity field at different wavelengths, and as such a hybrid architecture mission implementing both has been presented. A measurement proof of concept study is performed for this proposed architecture, analyzing the possible improvements over current best time-variable gravity models at mid and small spatial scales and the effects of prominent sources of error. A series of simulations is performed through an orbit that is nearly polar, nearly circular, with an altitude of 450 km and the satellites spaced 220 km apart. The noises present in the gradiometer and pointing knowledge, which serves as a second form of gradiometer error, are tested in combination at varying levels to gain insight into their impact upon the accuracy of the resulting estimated gravity field. The impact of aliasing error upon this hybrid architecture is also tested and analyzed. The results demonstrate clear improvement over the GRACE-FO architecture when the gradiometer noise is sufficiently small. Even at the largest gradiometer noise levels, the inclusion of the gravity gradient data greatly reduces the impact of aliasing error. At varying noise levels, it is shown that either the gradiometer or attitude determination system can become the limiting factor of the architecture. This analysis serves to quantify the improvements in gravity field recovery a hybrid architecture can create with both current and under-development technologies.Aerospace Engineerin

Spatio-Velocity CSF as a Function of Retinal Velocity Using Unstabilized Stimuli

LCD televisions have LC response times and hold-type data cycles that contribute to the appearance of blur when objects are in motion on the screen. New algorithms based on studies of the human visual system\u27s sensitivity to motion are being developed to compensate for these artifacts. This paper describes a series of experiments that incorporate eyetracking in the psychophysical determination of spatio-velocity contrast sensitivity in order to build on the 2D spatiovelocity contrast sensitivity function (CSF) model first described by Kelly and later refined by Daly. We explore whether the velocity of the eye has an additional effect on sensitivity and whether the model can be used to predict sensitivity to more complex stimuli. There were a total of five experiments performed in this research. The first four experiments utilized Gabor patterns with three different spatial and temporal frequencies and were used to investigate and/or populate the 2D spatio-velocity CSF. The fifth experiment utilized a disembodied edge and was used to validate the model. All experiments used a two interval forced choice (2IFC) method of constant stimuli guided by a QUEST routine to determine thresholds. The results showed that sensitivity to motion was determined by the retinal velocity produced by the Gabor patterns regardless of the type of motion of the eye. Based on the results of these experiments the parameters for the spatio-velocity CSF model were optimized to our experimental conditions

The effect of follicular fluid hormones on oocyte recovery after ovarian stimulation: FSH level predicts oocyte recovery.

BackgroundOvarian stimulation for assisted reproductive technology (ART) overcomes the physiologic process to develop a single dominant follicle. However, following stimulation, egg recovery rates are not 100%. The objective of this study is to determine if the follicular fluid hormonal environment is associated with oocyte recovery.MethodsThis is a prospective study involving patients undergoing ART by standard ovarian stimulation protocols at an urban academic medical center. A total of 143 follicular fluid aspirates were collected from 80 patients. Concentrations of FSH, hCG, estradiol, progesterone, testosterone and prolactin were determined. A multivariable regression analysis was used to investigate the relationship between the follicular fluid hormones and oocyte recovery.ResultsIntrafollicular FSH was significantly associated with oocyte recovery after adjustment for hCG (Adjusted odds ratio (AOR) = 1.21, 95%CI 1.03-1.42). The hCG concentration alone, in the range tested, did not impact the odds of oocyte recovery (AOR = 0.99, 95%CI 0.93-1.07). Estradiol was significantly associated with oocyte recovery (AOR = 0.98, 95% CI 0.96-0.99). After adjustment for progesterone, the strength of association between FSH and oocyte recovery increased (AOR = 1.84, 95%CI 1.45-2.34).ConclusionThe relationship between FSH and oocyte recovery is significant and appears to work through mechanisms independent of the sex hormones. FSH may be important for the physiologic event of separation of the cumulus-oocyte complex from the follicle wall, thereby influencing oocyte recovery. Current methods for inducing the final stages of oocyte maturation, with hCG administration alone, may not be optimal. Modifications of treatment protocols utilizing additional FSH may enhance oocyte recovery

Can Spreadsheet Solvers Solve Demanding Optimization Problems?

Practicing engineers resort to modular simulators or to algebraic tools such as GAMS or AMPL for performing complex process optimizations. These tools, however, have a significant learning curve unless they have been introduced at the undergraduate level beforehand. In this work we show how the Solver feature of the Excel spreadsheet can be used for the optimization of a fairly complex system, i.e., a classic solvent extraction/pollution prevention with heat integration process. The specific goal was the design optimization for continuous recovery of organic solvents (VOCs) using a gas absorption tower with solvent recovery in a stripper. It is shown that the Solver feature of the Excel spreadsheet can be used to converge on local optima for these complex systems, provided proper care is taken in the solution procedure. The complexities of optimization can also be demonstrated with this tool, as can several common pitfalls encountered during optimization

Observations of Stratospheric Sudden Warmings in Earth Rotation Variations

Stratospheric sudden warmings (SSWs) are extreme events in the polar stratosphere that are both caused by and have effects on the tropospheric flow. This means that SSWs are associated with changes in the angular momentum of the atmosphere, both before and after their onset. Because these angular momentum changes are transferred to the solid Earth, they can be observed in the rate of the Earth's rotation and the wobble of its rotational pole. By comparing observed Earth rotation variations to reanalysis data, we find that an anomaly in the orientation of the Earth's rotational pole, up to 4 times as large as the annual polar wobble, typically precedes SSWs by 20-40 days. The polar motion signal is due to pressure anomalies that are typically seen before SSW events and represents a new type of observable that may aid in the prediction of SSWs. A decline in the length of day is also seen, on average, near the time of the SSW wind reversal and is found to be due to anomalous easterly winds generated in the tropical troposphere around this time, though the structure and timing of this signal seems to vary widely from event to event