The Experts below are selected from a list of 207 Experts worldwide ranked by ideXlab platform
Bahram Jalali - One of the best experts on this subject based on the ideXlab platform.
-
anamorphic time stretch transform and its application to analog bandwidth compression
IEEE Global Conference on Signal and Information Processing, 2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A method for compressing the time-bandwidth of analog signals is introduced and demonstrated. As one of its applications, this mathematical transformation performs feature-selective time-stretch. When used as an analog pre-processor before the digitizer, it enables capture of random signals that would otherwise be beyond digitizer's bandwidth. At the same time, it compresses the digital data volume. Our method is lossless and does not require prior knowledge of the signal. It is inspired by operation of Fovea Centralis in human eye and by anamorphic transformation in visual arts. Implemented in the digital domain, the proposed transform also performs data and image compression.
-
anamorphic transformation and its application to time bandwidth compression
Applied Optics, 2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A general method for compressing the modulation time–bandwidth product of analog signals is introduced. As one of its applications, this physics-based signal grooming, performed in the analog domain, allows a conventional digitizer to sample and digitize the analog signal with variable resolution. The net result is that frequency components that were beyond the digitizer bandwidth can now be captured and, at the same time, the total digital data size is reduced. This compression is lossless and is achieved through a feature selective reshaping of the signal’s complex field, performed in the analog domain prior to sampling. Our method is inspired by operation of Fovea Centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a data compression algorithm to alleviate the storage and transmission bottlenecks associated with “big data.”
-
Anamorphic transformation and its application to time–bandwidth compression
Applied optics, 2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A general method for compressing the modulation time–bandwidth product of analog signals is introduced. As one of its applications, this physics-based signal grooming, performed in the analog domain, allows a conventional digitizer to sample and digitize the analog signal with variable resolution. The net result is that frequency components that were beyond the digitizer bandwidth can now be captured and, at the same time, the total digital data size is reduced. This compression is lossless and is achieved through a feature selective reshaping of the signal’s complex field, performed in the analog domain prior to sampling. Our method is inspired by operation of Fovea Centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a data compression algorithm to alleviate the storage and transmission bottlenecks associated with “big data.”
-
anamorphic transformation and its application to time bandwidth compression
arXiv: Optics, 2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A general method for compressing the modulation time-bandwidth product of analog signals is introduced and experimentally demonstrated. As one of its applications, this physics-based signal grooming performs feature-selective stretch, enabling a conventional digitizer to capture fast temporal features that were beyond its bandwidth. At the same time, the total digital data size is reduced. The compression is lossless and is achieved through a same-domain transformation of the signal's complex field, performed in the analog domain prior to digitization. Our method is inspired by operation of Fovea Centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a digital data compression algorithm to alleviate the storage and transmission bottlenecks associated with "big data".
-
Anamorphic Spectrum Transform and its Application to Time-Bandwidth Compression
2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A general method for compressing the modulation time-bandwidth product of analog signals is introduced and experimentally demonstrated. As one of its applications, this physics-based signal grooming performs feature-selective stretch, enabling a conventional digitizer to capture fast temporal features that were beyond its bandwidth. At the same time, the total digital data size is reduced. The compression is lossless and is achieved through a same-domain transformation of the signal's complex field, performed in the analog domain prior to digitization. Our method is inspired by operation of Fovea Centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a digital data compression algorithm to alleviate the storage and transmission bottlenecks associated with "big data".
Mohammad H. Asghari - One of the best experts on this subject based on the ideXlab platform.
-
anamorphic time stretch transform and its application to analog bandwidth compression
IEEE Global Conference on Signal and Information Processing, 2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A method for compressing the time-bandwidth of analog signals is introduced and demonstrated. As one of its applications, this mathematical transformation performs feature-selective time-stretch. When used as an analog pre-processor before the digitizer, it enables capture of random signals that would otherwise be beyond digitizer's bandwidth. At the same time, it compresses the digital data volume. Our method is lossless and does not require prior knowledge of the signal. It is inspired by operation of Fovea Centralis in human eye and by anamorphic transformation in visual arts. Implemented in the digital domain, the proposed transform also performs data and image compression.
-
anamorphic transformation and its application to time bandwidth compression
Applied Optics, 2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A general method for compressing the modulation time–bandwidth product of analog signals is introduced. As one of its applications, this physics-based signal grooming, performed in the analog domain, allows a conventional digitizer to sample and digitize the analog signal with variable resolution. The net result is that frequency components that were beyond the digitizer bandwidth can now be captured and, at the same time, the total digital data size is reduced. This compression is lossless and is achieved through a feature selective reshaping of the signal’s complex field, performed in the analog domain prior to sampling. Our method is inspired by operation of Fovea Centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a data compression algorithm to alleviate the storage and transmission bottlenecks associated with “big data.”
-
Anamorphic transformation and its application to time–bandwidth compression
Applied optics, 2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A general method for compressing the modulation time–bandwidth product of analog signals is introduced. As one of its applications, this physics-based signal grooming, performed in the analog domain, allows a conventional digitizer to sample and digitize the analog signal with variable resolution. The net result is that frequency components that were beyond the digitizer bandwidth can now be captured and, at the same time, the total digital data size is reduced. This compression is lossless and is achieved through a feature selective reshaping of the signal’s complex field, performed in the analog domain prior to sampling. Our method is inspired by operation of Fovea Centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a data compression algorithm to alleviate the storage and transmission bottlenecks associated with “big data.”
-
anamorphic transformation and its application to time bandwidth compression
arXiv: Optics, 2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A general method for compressing the modulation time-bandwidth product of analog signals is introduced and experimentally demonstrated. As one of its applications, this physics-based signal grooming performs feature-selective stretch, enabling a conventional digitizer to capture fast temporal features that were beyond its bandwidth. At the same time, the total digital data size is reduced. The compression is lossless and is achieved through a same-domain transformation of the signal's complex field, performed in the analog domain prior to digitization. Our method is inspired by operation of Fovea Centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a digital data compression algorithm to alleviate the storage and transmission bottlenecks associated with "big data".
-
Anamorphic Spectrum Transform and its Application to Time-Bandwidth Compression
2013Co-Authors: Mohammad H. Asghari, Bahram JalaliAbstract:A general method for compressing the modulation time-bandwidth product of analog signals is introduced and experimentally demonstrated. As one of its applications, this physics-based signal grooming performs feature-selective stretch, enabling a conventional digitizer to capture fast temporal features that were beyond its bandwidth. At the same time, the total digital data size is reduced. The compression is lossless and is achieved through a same-domain transformation of the signal's complex field, performed in the analog domain prior to digitization. Our method is inspired by operation of Fovea Centralis in the human eye and by anamorphic transformation in visual arts. The proposed transform can also be performed in the digital domain as a digital data compression algorithm to alleviate the storage and transmission bottlenecks associated with "big data".
Robert Salus - One of the best experts on this subject based on the ideXlab platform.
-
DAS GEFÄSSSYSTEM DER Fovea Centralis
Acta Ophthalmologica, 2009Co-Authors: Robert SalusAbstract:Zusammenfassung: I. Entgegen der herrschenden Ansicht von ihrer Gefasslosigkeit besitzt die Fovea Centralis ein kompliziertes Gefass-system, das in seinem regel- und gesetzmassigen Aufbau, in seinem Reichtum an allerdings ganz feinen Gefass-chen der Bedeutung dieses Bezirkes als funktionellem Centrum der Netzhaut voll entspricht. II. Beschreibung dieses Systems, s. Abb. I u. Tafel I. III. Schon aus dem blossen Vorhandensein des Fovealen Gefasssystems, aber auch aus mehreren anderen, vor allem klinischen Grunden kann man schliessen, dass die ganze Netzhaut in allen ihren Schichten von den Netzhautgefassen versorgt wird. Dementsprechend wird die herrschende Ansicht, dass die Fovea sowie das ubrige Neuroepithel von der Aderhaut her ernahrt wird, abgelehnt. IV. Die pathologischen Veranderungen, sowie die spezielle ophthalmoskopische Diagnostik des Gefasssystems der Fovea centr. a. Die Altersveranderungen u. die Altersarteriosklerose b. die Fovea hypertonica. Abb. II, Tafel II c. Fovea bei blassem Hochdruck, die Retinitis albuminurica u. andere Retinitiden.
Diego Rativa - One of the best experts on this subject based on the ideXlab platform.
-
ultrasmall spot size scanning laser ophthalmoscopy
Biomedical Optics Express, 2011Co-Authors: Brian Vohnsen, Diego RativaAbstract:An ultrasmall spot size scanning laser ophthalmoscope has been developed that employs an annular aberration-corrected incident beam to increase the effective numerical aperture of the eye thereby reducing the width of the probing light spot. ParaFovea and Foveal cone photoreceptor visibility determined from small area retinal image scans are discussed from the perspective of mode matching between the focused incident beam and the waveguide modes of individual cones. The cone visibility near the Fovea Centralis can be increased with the annular illumination scheme whereas the visibility of larger paraFovea cones drops significantly as a consequence of poorer mode match. With further improvements of the implemented wavefront correction technology it holds promise for individual cone-photoreceptor imaging at the Fovea Centralis and for optical targeting of the retina with increased resolution.
S Otake - One of the best experts on this subject based on the ideXlab platform.
-
FoveaL L AND M CONE RATIO AND TOPOGRAPHY ESTIMATED WITH CHROMATIC HYPERACUITY STIMULI
Investigative Ophthalmology & Visual Science, 1993Co-Authors: Pd Gowdy, Cm Cicerone, S OtakeAbstract:FoveaL LAND M CONE RATIO AND TOPOGRAPHY ESTIMATED Wl'rH CHROMATIC HYPERAClnTY STIMULI P. D. G9wc1y. C. M 1 Cicerone, and S. Otake University of California, Irvine, CA. pymos~. The high Foveal cone density and the optical characteristics of the human eye are barriers to psychophysical measurements of the separate topographies of L and M cones in Fovea Centralis. The aims of this study, for central Fovea, were (1) to devise a method allowing the estimation of the topographies of L - and M-cones, and (2) to provide a novel method for estimating the relative numbers of L~ and M-cones. Methods. Monochromatic (620, 560, and 520nm) vernier dot stimuli (1' of arc squares with 3' of arc separation, 200ms dw-ation) were presented with target (top) displacements ranging from O to 70 of arc to the left and right of the reference (lower) upon selective, cone- suppressing background fields. The task was to indicate whether the target was displaced to the left or right of the reference dot in each self-presented trial. The data generated from computer simulations, talting into account optical scatter, eye movements, and different configurations of L- and M-cone mosaics, were matched to the experimental data to estimate the L- and M-cone ratio and their topographies for each observer. Results. Obtained L- and M-cone ratios were in close agreement with previous estimates based on a small-spot detection task (Cicerone and Nerger, 1989; Otake and Cicerone, 1992). The simulation-gen.e rated mosaic that best matched the data specified each observer's underlying cone mosaic. Copclusions. We show that this novel method can be used to estimate cone ratios as well as the separate topographies of L- and M-cones in the densely-packed photoreceptor array of Fovea Centralis. Supported by NSF-BNS 8819874 and NIH-EY 08200 to CMC. None.
-
THE DISTRIBUTION OF CONES IN THE LIVING HUMAN EYE
Investigative Ophthalmology & Visual Science, 1993Co-Authors: S Otake, Cm CiceroneAbstract:THE DJSTBlBtmON OF CONE5 INTBE LIVING HUMAN EYE S. Ot,oke and C. M. Cicerone University of California. Irvine, CA pPi:pose, We Bought t,o estimate the density of cones at varying nasal and temporal eccentricities in the living human. eye. Methods. We developed a new method for estimating cone denaity over a range of eccentricities (Fovea Centralis; 2. 7, 17, and 28 deg nasal; and 2, 7, and 28 deg temporal). Measurements were made of the probability of detection for small spots of either 520 nm or 640 nm under M cone or L cone isolating condition.s, respectively. These results were compared to simulations baaed on a model which took into account the measured irradiance of the test .flash, the preretinal absorption in the eye. optical scatter, and eye movements. We assumed a hexagonal packing for the cones, the Smith and Pokomy fundamentals.) and ·values for the number of quanta required t.o excite a cone (Otake and Cicerone. 1992), for pigment density (Baylor et al •• 1987). and for cone dimensions (Curcio. 1991). The simulations that best fit our results gave us the density of cones, excluding S cones. Besuly. Our results are in good agreement with anatolllical measurements. For example, for three observers we estimated cone densities in the Fovea Centralis of 9.5 x 10 4 , 1.4 x 10s. and 1.8 x 105 cones per mm.2. These values are comparable to anatomical estimates in the human eye: Curcio et al. (1990) obtained 1.992 x 105 cones per mm2 as a mean value for measurements in four eyes, and 0sterberg's (1935) value wae 1.4 73 x 105 cones per mm2 measured in one eye. ConelusiOJJI· Our study provides the first eetimates of the density of cones in the living human eye over a wide range of nasal and temporal eccentricities, These psychophysically obt.ained values are comparable to anatomical results. Supported by NSF-BNS8819874 and NIH-EY08200 to CMC. None
