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The optical quality of an image depends on both the optical properties of the imaging system and the physical properties of the medium in which the light travels from the object to the final imaging sensor. The analysis of the point spread function of the optical system is an objective way to quantify the image degradation. In retinal imaging, the presence of corneal or cristalline lens opacifications spread the light at wide angular distributions. If the mathematical operator that degrades the image is known, the image can be restored through deconvolution methods. In the particular case of retinal imaging, this operator may be unknown (or partially) due to the presence of cataracts, corneal edema, or vitreous opacification. In those cases, blind deconvolution theory provides useful results to restore important spatial information of the image. In this work, a new semi-blind deconvolution method has been developed by training an iterative process with the Glare Spread Function kernel based on the Richardson-Lucy deconvolution algorithm to compensate a veiling glare effect in retinal images due to intraocular straylight. The method was first tested with simulated retinal images generated from a straylight eye model and applied to a real retinal image dataset composed of healthy subjects and patients with glaucoma and diabetic retinopathy. Results showed the capacity of the algorithm to detect and compensate the veiling glare degradation and improving the image sharpness up to 1000% in the case of healthy subjects and up to 700% in the pathological retinal images. This image quality improvement allows performing image segmentation processing with restored hidden spatial information after deconvolution.
Francisco Ávila; Jorge Ares; María Marcellán; María Collados; Laura Remón. Iterative-Trained Semi-Blind Deconvolution Algorithm to Compensate Straylight in Retinal Images. Journal of Imaging 2021, 7, 73 .
AMA StyleFrancisco Ávila, Jorge Ares, María Marcellán, María Collados, Laura Remón. Iterative-Trained Semi-Blind Deconvolution Algorithm to Compensate Straylight in Retinal Images. Journal of Imaging. 2021; 7 (4):73.
Chicago/Turabian StyleFrancisco Ávila; Jorge Ares; María Marcellán; María Collados; Laura Remón. 2021. "Iterative-Trained Semi-Blind Deconvolution Algorithm to Compensate Straylight in Retinal Images." Journal of Imaging 7, no. 4: 73.
A building integrated holographic concentrating photovoltaic-thermal system has been optically and energetically simulated. The system has been designed to be superimposed into a solar shading louvre; in this way the concentrating unit takes profit of the solar altitude tracking, which the shading blinds already have, to increase system performance. A dynamic energy simulation has been conducted in two different locations—Sde Boker (Israel) and Avignon (France)—both with adequate annual irradiances for solar applications, but with different weather and energy demand characteristics. The simulation engine utilized has been TRNSYS, coupled with MATLAB (where the ray-tracing algorithm to simulate the holographic optical performance has been implemented). The concentrator achieves annual mean optical efficiencies of 30.3% for Sde Boker and 43.0% for the case of Avignon. Regarding the energy production, in both locations the thermal energy produced meets almost 100% of the domestic hot water demand as this has been considered a priority in the system control. On the other hand, the space heating demands are covered by a percentage ranging from 15% (Avignon) to 20% (Sde Boker). Finally, the electricity produced in both places covers 7.4% of the electrical demand profile for Sde Boker and 9.1% for Avignon.
Julia Marín-Sáez; Daniel Chemisana; Álex Moreno; Alberto Riverola; Jesús Atencia; María-Victoria Collados. Energy Simulation of a Holographic PVT Concentrating System for Building Integration Applications. Energies 2016, 9, 577 .
AMA StyleJulia Marín-Sáez, Daniel Chemisana, Álex Moreno, Alberto Riverola, Jesús Atencia, María-Victoria Collados. Energy Simulation of a Holographic PVT Concentrating System for Building Integration Applications. Energies. 2016; 9 (8):577.
Chicago/Turabian StyleJulia Marín-Sáez; Daniel Chemisana; Álex Moreno; Alberto Riverola; Jesús Atencia; María-Victoria Collados. 2016. "Energy Simulation of a Holographic PVT Concentrating System for Building Integration Applications." Energies 9, no. 8: 577.
We have designed and developed a pulse compressor with volume transmission holographic gratings to be implemented in post-compression experiments based on filamentation in gases. Pulse compression down to 13 fs has been demonstrated. The gratings have been recorded in commercial PFG-04 dichromated gelatin emulsions with a recording wavelength of 532 nm, attaining sufficient index modulation to achieve high efficiency when they are illuminated by an 800-nm laser.
A. Villamarín; I. J. Sola; M. V. Collados; J. Atencia; O. Varela; Benjamin Alonso; C. Méndez; J. San Román; I. Arias; L. Roso; M. Quintanilla. Compensation of second-order dispersion in femtosecond pulses after filamentation using volume holographic transmission gratings recorded in dichromated gelatin. Applied Physics A 2011, 106, 135 -141.
AMA StyleA. Villamarín, I. J. Sola, M. V. Collados, J. Atencia, O. Varela, Benjamin Alonso, C. Méndez, J. San Román, I. Arias, L. Roso, M. Quintanilla. Compensation of second-order dispersion in femtosecond pulses after filamentation using volume holographic transmission gratings recorded in dichromated gelatin. Applied Physics A. 2011; 106 (1):135-141.
Chicago/Turabian StyleA. Villamarín; I. J. Sola; M. V. Collados; J. Atencia; O. Varela; Benjamin Alonso; C. Méndez; J. San Román; I. Arias; L. Roso; M. Quintanilla. 2011. "Compensation of second-order dispersion in femtosecond pulses after filamentation using volume holographic transmission gratings recorded in dichromated gelatin." Applied Physics A 106, no. 1: 135-141.