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Pilling is a defect that affects the appearance of fabrics, being its assessment carried out by the textile sector using a subjective method (reference). This method is simple and works well in most cases. However, uncertainties may arise when complicated cases are under evaluation. The current study addresses the use of an optical 3D-system for the topographic surface reconstruction of fabrics for their objective assessment. With the topographic data of the fabrics, it was calculated the total volume of pilling formed in their surfaces. Their equivalent pilling grades were also achieved through use of a correspondence model. A results comparison was then carried out with both methodologies (3D-system and subjective), which made possible to identify cases of analysis where the grading attributed to the fabrics did not match. These cases were thoroughly analyzed, and it was found that one of the studied fabrics seems to have been over-estimated whereas one other seems to have been under-estimated when initially graded with the subjective methodology.
António De Oliveira Mendes; Paulo Fiadeiro; Rui A. L. Miguel; José M. Lucas; Manuel J. Dos Santos Silva. Optical 3D-system for fabric pilling assessment: A complementary tool to avoid evaluation errors. The Journal of The Textile Institute 2020, 112, 921 -927.
AMA StyleAntónio De Oliveira Mendes, Paulo Fiadeiro, Rui A. L. Miguel, José M. Lucas, Manuel J. Dos Santos Silva. Optical 3D-system for fabric pilling assessment: A complementary tool to avoid evaluation errors. The Journal of The Textile Institute. 2020; 112 (6):921-927.
Chicago/Turabian StyleAntónio De Oliveira Mendes; Paulo Fiadeiro; Rui A. L. Miguel; José M. Lucas; Manuel J. Dos Santos Silva. 2020. "Optical 3D-system for fabric pilling assessment: A complementary tool to avoid evaluation errors." The Journal of The Textile Institute 112, no. 6: 921-927.
This work was motivated by previous studies on the perceptual influence of chromatic impairments, where was observed that specific chromatic impairments might have a different influence, related to the represented content. Hence, in this study, chromatic impairments were applied to specific color clusters and the resulting perceptual influence was analyzed. The applied chromatic impairments influence on the images naturalness was assessed using a Single Stimulus Continuous Quality Evaluation (SSCQE) and the Mean Opinion Score (MOS) was calculated. Furthermore, during the image assessment, the eye movements were registered using an eye tracking device and the Relative Fixation Time (RFT) was computed. It was concluded that the induced chromatic impairments, lead to lower MOS values than the original images, revealing a perception of quality loss. Furthermore, when nature colors are changed, subjects revealed a larger perception of the impairment, resulting in smaller MOS and producing evident changes in the RFT’s. The comparative analysis between the MOS and the RFT’s reveals high Pearson Correlation Coefficient (PCC) results (p = 0.79 ± 0.14).
Marco V. Bernardo; António M. G. Pinheiro; Paulo T. Fiadeiro; Manuela Pereira. Quality perception of specific chromatic impairments. Multimedia Tools and Applications 2020, 79, 19831 -19851.
AMA StyleMarco V. Bernardo, António M. G. Pinheiro, Paulo T. Fiadeiro, Manuela Pereira. Quality perception of specific chromatic impairments. Multimedia Tools and Applications. 2020; 79 (27-28):19831-19851.
Chicago/Turabian StyleMarco V. Bernardo; António M. G. Pinheiro; Paulo T. Fiadeiro; Manuela Pereira. 2020. "Quality perception of specific chromatic impairments." Multimedia Tools and Applications 79, no. 27-28: 19831-19851.
Digital holography is an emerging imaging technique for displaying and sensing three-dimensional objects. The perceived image quality of a hologram is frequently corrupted by speckle noise due to coherent illumination. Although several speckle noise reduction methods have been developed so far, there are scarce quality assessment studies to address their performance, and they typically focus solely on objective metrics. However, these metrics do not reflect the visual quality perceived by a human observer. In this work, the performances of four speckle reduction algorithms, namely, the nonlocal means–the Lee, the Frost, and the block-matching 3D filters, with varying parameterizations–were subjectively evaluated. The results were ranked with respect to the perceived image quality to obtain the mean opinion scores using pairwise comparison. The correlation between the subjective results and 20 different no-reference objective quality metrics was evaluated. The experiment indicates that block-matching 3D and Lee are the preferred filters, depending on hologram characteristics. The best-performing objective metrics were identified for each filter.
Elsa Fonseca; Paulo Fiadeiro; Marco Bernardo; Antonio Pinheiro; Manuela Pereira. Assessment of speckle denoising filters for digital holography using subjective and objective evaluation models. Applied Optics 2019, 58, G282 -G292.
AMA StyleElsa Fonseca, Paulo Fiadeiro, Marco Bernardo, Antonio Pinheiro, Manuela Pereira. Assessment of speckle denoising filters for digital holography using subjective and objective evaluation models. Applied Optics. 2019; 58 (34):G282-G292.
Chicago/Turabian StyleElsa Fonseca; Paulo Fiadeiro; Marco Bernardo; Antonio Pinheiro; Manuela Pereira. 2019. "Assessment of speckle denoising filters for digital holography using subjective and objective evaluation models." Applied Optics 58, no. 34: G282-G292.
The pseudophakic eye lacks the ability to produce a refractive change in response to object proximity. Thus, individual anatomical features such as the pupil size play an important role in achieving functional vision levels. In this work, the range of pupil sizes at varying object distance was measured in pseudophakic participants. Furthermore, the impact of the measured values on eye optical quality was investigated using a computer simulation model. A binocular eye-tracker was used to measure the participants’ pupil sizes at six object distances, ranging from 0.33 m (i.e., vergence of 3.00 D) to 3.00 m (i.e., vergence of 0.33 D), while observing a Maltese cross with a constant angular size of 1 ∘ . In total, 58 pseudophakic participants were enrolled in this study (age mean ± standard deviation: 70.5 ± 11.3 years). The effects of object distance and age on pupil size variation were investigated using linear mixed effects regression models. Age was found to have a small contribution to individual variability. The mean infinite distance pupil size (intercept) was 4.45 ( 95 % CI: 2.74, 6.17) mm and the mean proximal miosis (slope) was − 0.23 ( 95 % CI: −0.53, 0.08) mm/D. The visual acuity (VA) estimation for a distant object ranged from − 0.1 logMAR (smallest pupil) to 0.04 logMAR (largest pupil) and the near VA ( 0.33 m) when mean proximal miosis was considered ranged from 0.28 logMAR (smallest pupil) to 0.42 logMAR (largest pupil). When mean distance pupil was considered, proximal miosis individual variability produced a variation of 0.04 logMAR for the near object and negligible variation for the distant object. These results support the importance of distance pupil size measurement for the prediction of visual performance in pseudophakia, while suggesting that proximal miosis has a negligible impact in VA variability.
Elsa Fonseca; Paulo Fiadeiro; Renato Gomes; Angel Sanchez Trancon; António Baptista; Pedro Serra. Pupil Function in Pseudophakia: Proximal Miosis Behavior and Optical Influence. Photonics 2019, 6, 114 .
AMA StyleElsa Fonseca, Paulo Fiadeiro, Renato Gomes, Angel Sanchez Trancon, António Baptista, Pedro Serra. Pupil Function in Pseudophakia: Proximal Miosis Behavior and Optical Influence. Photonics. 2019; 6 (4):114.
Chicago/Turabian StyleElsa Fonseca; Paulo Fiadeiro; Renato Gomes; Angel Sanchez Trancon; António Baptista; Pedro Serra. 2019. "Pupil Function in Pseudophakia: Proximal Miosis Behavior and Optical Influence." Photonics 6, no. 4: 114.
In pseudophakia, the eye is unable accommodate so proximal objects can be properly focused. Achieving functional vision levels relies on individual anatomical features, notably, the pupil size. This study measured the range of pupil sizes found in a population of pseudophakes, for an object placed at different distances, and modeled the optical quality associated to pupil variation. The pupil size of 58 pseudophakic eyes (age mean ± standard deviation: 70.5 ± 11.3 years) was measured using a binocular eye-tracker. The participants observed on a monitor a circular white patch subtending 5° with a cross on its center. The object was placed at 3.0, 1.0, 0.66, 0.5, 0.4, 0.33 m. The pupil size variation as a function of object distance was modelled using a linear mixed effects model. The mean and 95% confidence interval (CI) were calculated for a far object and the slope of the function, indicative of the proximal myosis. The effect of object distance on the image quality was modeled using a pseudophakic model eye for the pupil size data. The mean distance pupil sizes were 4.45 (95%CI: 2.74, 6.17) mm and the mean proximal myosis was -0.23 (95%CI: -0.53, -0.08) mm/D. The VA estimation for a distance object ranged from -0.1 logMAR for the smallest pupil to 0.08 logMAR and the near VA when mean myosis was considered ranged from 0.28 logMAR to 0.65 logMAR. These results support the importance of distance pupil size measurement for the prediction of visual performance in pseudophakia, while suggesting that myosis has a negligible impact in VA variability.
Elsa Fonseca; Paulo Fiadeiro; Renato Gomes; Angel Sanchez Trancon; António M. G. Baptista; Pedro M. Serra. Influence of pupil function in pseudophakia. Fourth International Conference on Applications of Optics and Photonics 2019, 11207, 112071N .
AMA StyleElsa Fonseca, Paulo Fiadeiro, Renato Gomes, Angel Sanchez Trancon, António M. G. Baptista, Pedro M. Serra. Influence of pupil function in pseudophakia. Fourth International Conference on Applications of Optics and Photonics. 2019; 11207 ():112071N.
Chicago/Turabian StyleElsa Fonseca; Paulo Fiadeiro; Renato Gomes; Angel Sanchez Trancon; António M. G. Baptista; Pedro M. Serra. 2019. "Influence of pupil function in pseudophakia." Fourth International Conference on Applications of Optics and Photonics 11207, no. : 112071N.
In this paper an optical triangulation system is used to perform the three-dimensional surface reconstruction of different textile fabrics for an objective evaluation of wrinkling. The system works by projecting a light stripe onto the surface of the fabric samples and according to the amount of wrinkling exhibited on them, the light stripe will suffer larger or smaller deviations. By moving the fabric samples relatively to the light stripe, a complete scan of the fabrics is achieved. This process leads then to the creation of 3D images of the fabrics on which it is possible to distinguish their topographic differences. With the collected data of the fabrics, it is also possible to calculate several parameters to evaluate the wrinkling quantitatively. As expected, both analyses considered in the current work are completely in agreement with the reference grades of the subjective wrinkling evaluation method.
António De Oliveira Mendes; Paulo Fiadeiro; Rui Alberto Lopes Miguel; José Mendes Lucas; Manuel José Dos Santos Silva. Three-dimensional surface reconstruction for evaluation of wrinkling on textile fabrics. Fourth International Conference on Applications of Optics and Photonics 2019, 11207, 1120703 .
AMA StyleAntónio De Oliveira Mendes, Paulo Fiadeiro, Rui Alberto Lopes Miguel, José Mendes Lucas, Manuel José Dos Santos Silva. Three-dimensional surface reconstruction for evaluation of wrinkling on textile fabrics. Fourth International Conference on Applications of Optics and Photonics. 2019; 11207 ():1120703.
Chicago/Turabian StyleAntónio De Oliveira Mendes; Paulo Fiadeiro; Rui Alberto Lopes Miguel; José Mendes Lucas; Manuel José Dos Santos Silva. 2019. "Three-dimensional surface reconstruction for evaluation of wrinkling on textile fabrics." Fourth International Conference on Applications of Optics and Photonics 11207, no. : 1120703.
The perceived image quality of a digital hologram of macroscopic objects is affected by its reduced depth of focus and by speckle noise due to coherent illumination. Several filtering techniques have been proposed for speckle noise reduction of digital holograms but there are scarce quality assessment studies regarding phase-shifting digital holograms. Typically, the performance of these filters on experimental holograms is assessed using no reference objective metrics. However, these metrics do not reflect the subjective visual quality perceived by a human observer. In this work, the performance of four speckle reduction algorithms, namely the non-local means, the Lee, the Frost and the block matching 3D filters, using five different parametrizations for each case, are subjectively compared. Due to a large amount of testing data, the subjective test was divided in two: 1) one phase where the effects of the parametrization of each method are evaluated, 2) a second phase where the best parametrization results are compared between them. The results are ranked with respect to the perceived image quality to obtain the Mean Opinion Scores for each filter/parameter combination. As in this case there is no reference image and double stimulus is desirable, the subjective evaluation was achieved using full paired comparison. The experiment indicates that BM3D and Lee are the preferred filters, and reveals a strong dependence of filter performance on hologram characteristics.
Elsa Fonseca; Paulo Fiadeiro; Vahid Hajihashemi; Marco Bernardo; Antonio Pinheiro; Manuela Pereira. Perceptual evaluation of speckle noise reduction techniques for phase shifting holograms. 2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX) 2019, 1 -6.
AMA StyleElsa Fonseca, Paulo Fiadeiro, Vahid Hajihashemi, Marco Bernardo, Antonio Pinheiro, Manuela Pereira. Perceptual evaluation of speckle noise reduction techniques for phase shifting holograms. 2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX). 2019; ():1-6.
Chicago/Turabian StyleElsa Fonseca; Paulo Fiadeiro; Vahid Hajihashemi; Marco Bernardo; Antonio Pinheiro; Manuela Pereira. 2019. "Perceptual evaluation of speckle noise reduction techniques for phase shifting holograms." 2019 Eleventh International Conference on Quality of Multimedia Experience (QoMEX) , no. : 1-6.
In previous work, a digital hologram compression scheme for representation on the object plane was proposed. Compression on object plane for experimental holograms and Computer-Generated Holograms (CGH) proves to be a very efficient model that outperforms the compression on the hologram plane. However, the compression gain is more relevant in CGHs. The difference between experimental holograms and CGHs is related to the fact that CGHs are less affected by speckle noise that is a characteristic of experimental holograms. In the current work, to improve the coding efficiency of the hologram compression scheme is proposed the reduction of speckle noise of experimental holograms. The compression scheme defines a base layer where a 2D version of the object is coded with an image codec standard. The efficiency of this step is much higher in case of CGH when compared to experimental holograms. However, after performing speckle noise reduction before any compression a similar compression efficiency is found. Since the speckle noise reduction is performed only on amplitude data without affecting the phase, is still possible to render 3D features such as depth map, multi-view or to recover holographic interference patterns for further 3D visualization.
Marco Bernardo; Elsa Fonseca; Antonio M. G. Pinheiro; Paulo T. Fiadeiro; Manuela Pereira. Speckle Reduction for Efficient Coding of Experimental Holograms. 2019 Data Compression Conference (DCC) 2019, 557 -557.
AMA StyleMarco Bernardo, Elsa Fonseca, Antonio M. G. Pinheiro, Paulo T. Fiadeiro, Manuela Pereira. Speckle Reduction for Efficient Coding of Experimental Holograms. 2019 Data Compression Conference (DCC). 2019; ():557-557.
Chicago/Turabian StyleMarco Bernardo; Elsa Fonseca; Antonio M. G. Pinheiro; Paulo T. Fiadeiro; Manuela Pereira. 2019. "Speckle Reduction for Efficient Coding of Experimental Holograms." 2019 Data Compression Conference (DCC) , no. : 557-557.
Digital holography is a growing field that owes its success to the provided three-dimensional imaging representation. This is achieved by encoding the wave field transmitted or scattered by an object in the form of an interference pattern with a reference beam. While in conventional imaging systems it is usually impossible to recover the correct focused image from a defocused one, with digital holography the image can be numerically retrieved at any distance from the hologram. Digital holography also allows the reconstruction of multiple objects at different depths. In a previous study, the benchmark of the main available image coding standard solutions JPEG, JPEG-XT, JPEG 2000 and the HEVC intra mode was performed for digital holographic data represented on the object plane. The HEVC intra main coding profile outperforms the other standards while JPEG 2000 results in very similar compression performance. In the current work, a scheme based on the HEVC intra mode codec for holographic information compression on the object plane is proposed. In the base layer, a 2D version of the object (amplitude information on object plane) is coded with HEVC intra main coding profile. Previously was observed that the phase information requires much higher bit rates than the amplitude information, as standardized codecs are not adapted for the compression of this type of information. In this paper we propose a model where the amplitude information is encoded with the HEVC intra mode codec, while the phase is represented by encoding the real information and the signal of the imaginary information. The real information is also encoded using the HEVC intra mode as it already revealed appropriate for compression of this type of information. The imaginary information signal is encoded with JBIG. The advantage of this scheme is that the amplitude information provides a direct 2D representation of the hologram while the phase information can be considered as a 3D enhancement layer. The results show that the proposed scheme outperforms the state of the art in holography compression, while allowing compatibility with the current standards and direct 2D visualization.
Antonio M. G. Pinheiro; Manuela Pereira; Elsa Fonseca; Paulo Fiadeiro; Marco V. Bernardo. A digital hologram compression scheme for representation on the object plane. Applications of Digital Image Processing XLI 2018, 10752, 107520J .
AMA StyleAntonio M. G. Pinheiro, Manuela Pereira, Elsa Fonseca, Paulo Fiadeiro, Marco V. Bernardo. A digital hologram compression scheme for representation on the object plane. Applications of Digital Image Processing XLI. 2018; 10752 ():107520J.
Chicago/Turabian StyleAntonio M. G. Pinheiro; Manuela Pereira; Elsa Fonseca; Paulo Fiadeiro; Marco V. Bernardo. 2018. "A digital hologram compression scheme for representation on the object plane." Applications of Digital Image Processing XLI 10752, no. : 107520J.
Digital holography allows the recording, storage and subsequent reconstruction of both amplitude and phase of the light field scattered by an object. This is accomplished by recording interference patterns that preserve the properties of the original object field essential for 3D visualization, the so-called holograms. Digital holography refers to the acquisition of holograms with a digital sensor, typically a CCD or a CMOS camera, and to the reconstruction of the 3D object field using numerical methods. In the current work, the different representations of digital holographic information in the hologram and in the object planes are studied. The coding performance of the different complex field representations, notably Amplitude-Phase and Real-Imaginary, in both the hologram plane and the object plane, is assessed using both computer generated and experimental holograms. The HEVC intra main coding profile is used for the compression of the different representations in both planes, either for experimental holograms or computer generated holograms. The HEVC intra compression in the object plane outperforms encoding in the hologram plane. Furthermore, encoding computer generated holograms in the object plane has a larger benefit than the same encoding over the experimental holograms. This difference was expected, since experimental holograms are affected by a larger negative influence of speckle noise, resulting in a loss of compression efficiency. This work emphasizes the possibility of holographic coding on the object plane, instead of the common encoding in the hologram plane approach. Moreover, this possibility allows direct visualization of the Object Plane Amplitude in a regular 2D display without any transformation methods. The complementary phase information can easily be used to render 3D features such as depth map, multi-view or even holographic interference patterns for further 3D visualization depending on the display technology.
Marco V. Bernardo; Pedro Fernandes; Angelo Arrifano; Marc Antonini; Elsa Fonseca; Paulo Fiadeiro; Antonio Pinheiro; Manuela Pereira. Holographic representation: Hologram plane vs. object plane. Signal Processing: Image Communication 2018, 68, 193 -206.
AMA StyleMarco V. Bernardo, Pedro Fernandes, Angelo Arrifano, Marc Antonini, Elsa Fonseca, Paulo Fiadeiro, Antonio Pinheiro, Manuela Pereira. Holographic representation: Hologram plane vs. object plane. Signal Processing: Image Communication. 2018; 68 ():193-206.
Chicago/Turabian StyleMarco V. Bernardo; Pedro Fernandes; Angelo Arrifano; Marc Antonini; Elsa Fonseca; Paulo Fiadeiro; Antonio Pinheiro; Manuela Pereira. 2018. "Holographic representation: Hologram plane vs. object plane." Signal Processing: Image Communication 68, no. : 193-206.
Numerical reconstruction of digital holograms relies on a precise knowledge of the original object position. However, there are a number of relevant applications where this parameter is not known in advance and an efficient autofocusing method is required. This paper addresses the problem of finding optimal focusing methods for use in reconstruction of digital holograms of macroscopic amplitude and phase objects, using digital in-line phase-shifting holography in transmission mode. Fifteen autofocus measures, including spatial-, spectral-, and sparsity-based methods, were evaluated for both synthetic and experimental holograms. The Fresnel transform and the angular spectrum reconstruction methods were compared. Evaluation criteria included unimodality, accuracy, resolution, and computational cost. Autofocusing under angular spectrum propagation tends to perform better with respect to accuracy and unimodality criteria. Phase objects are, generally, more difficult to focus than amplitude objects. The normalized variance, the standard correlation, and the Tenenbaum gradient are the most reliable spatial-based metrics, combining computational efficiency with good accuracy and resolution. A good trade-off between focus performance and computational cost was found for the Fresnelet sparsity method.
Elsa S. R. Fonseca; Paulo T. Fiadeiro; Manuela Pereira; António Pinheiro. Comparative analysis of autofocus functions in digital in-line phase-shifting holography. Applied Optics 2016, 55, 7663 .
AMA StyleElsa S. R. Fonseca, Paulo T. Fiadeiro, Manuela Pereira, António Pinheiro. Comparative analysis of autofocus functions in digital in-line phase-shifting holography. Applied Optics. 2016; 55 (27):7663.
Chicago/Turabian StyleElsa S. R. Fonseca; Paulo T. Fiadeiro; Manuela Pereira; António Pinheiro. 2016. "Comparative analysis of autofocus functions in digital in-line phase-shifting holography." Applied Optics 55, no. 27: 7663.
The influence of chromatic impairments on the perceived image quality is studied in this article. Under the D65 standard illuminant, a set of hyperspectral images were represented into the CIELAB color space, and the corresponding chromatic coordinates were subdivided into clusters with the k -means algorithm. Each color cluster was shifted by a predefined chromatic impairment Δ E * ab with random direction in a * b * chromatic coordinates only. Applying impairments of 3, 6, 9, 12, and 15 in a * b * coordinates to five hyperspectral images a set of modified images was generated. Those images were shown to subjects that were asked to rank their quality based on their naturalness. The Mean Opinion Score of the subjective evaluations was computed to quantify the sensitivity to the chromatic variations. This article is also complemented with an objective evaluation of the quality using several state-of-the-art metrics and using the CIEDE2000 color difference among others. Analyzing the correlations between subjective and objective quality evaluation helps us to conclude that the proposed quality estimators based on the CIEDE2000 provide the best representation. Moreover, it was concluded that the established quality metrics only become reliable by averaging their results on each color component.
Marco Bernardo; Antonio Pinheiro; Paulo Fiadeiro; Manuela Pereira. Image Quality under Chromatic Impairments. ACM Transactions on Applied Perception 2016, 14, 1 -20.
AMA StyleMarco Bernardo, Antonio Pinheiro, Paulo Fiadeiro, Manuela Pereira. Image Quality under Chromatic Impairments. ACM Transactions on Applied Perception. 2016; 14 (1):1-20.
Chicago/Turabian StyleMarco Bernardo; Antonio Pinheiro; Paulo Fiadeiro; Manuela Pereira. 2016. "Image Quality under Chromatic Impairments." ACM Transactions on Applied Perception 14, no. 1: 1-20.
Pedro Fernandes; Marco V. Bernardo; António M. G. Pinheiro; Paulo T. Fiadeiro; Manuela Pereira. Quality comparison of the HEVC and VP9 encoders performance. Multimedia Tools and Applications 2016, 76, 13633 -13649.
AMA StylePedro Fernandes, Marco V. Bernardo, António M. G. Pinheiro, Paulo T. Fiadeiro, Manuela Pereira. Quality comparison of the HEVC and VP9 encoders performance. Multimedia Tools and Applications. 2016; 76 (11):13633-13649.
Chicago/Turabian StylePedro Fernandes; Marco V. Bernardo; António M. G. Pinheiro; Paulo T. Fiadeiro; Manuela Pereira. 2016. "Quality comparison of the HEVC and VP9 encoders performance." Multimedia Tools and Applications 76, no. 11: 13633-13649.
In recent years, periocular recognition has become a popular alternative to face and iris recognition in less ideal acquisition scenarios. An interesting example of such scenarios is the usage of mobile devices for recognition purposes. With the growing popularity and easy access to such devices, the development of robust biometric recognition algorithms to work under such conditions finds strong motivation. In the present work we assess the performance of extended versions of two state-of-the-art periocular recognition algorithms on the publicly available CSIP database, a recent dataset composed of images acquired under highly unconstrained and multi-sensor mobile scenarios. The achieved results show each algorithm is better fit to tackle different scenarios and applications of the biometric recognition problem
João C. Monteiro; Rui Esteves; Gil Santos; Paulo Fiadeiro; Joana Lobo; Jaime Cardoso. A Comparative Analysis of Two Approaches to Periocular Recognition in Mobile Scenarios. Computer Vision 2015, 268 -280.
AMA StyleJoão C. Monteiro, Rui Esteves, Gil Santos, Paulo Fiadeiro, Joana Lobo, Jaime Cardoso. A Comparative Analysis of Two Approaches to Periocular Recognition in Mobile Scenarios. Computer Vision. 2015; ():268-280.
Chicago/Turabian StyleJoão C. Monteiro; Rui Esteves; Gil Santos; Paulo Fiadeiro; Joana Lobo; Jaime Cardoso. 2015. "A Comparative Analysis of Two Approaches to Periocular Recognition in Mobile Scenarios." Computer Vision , no. : 268-280.
An innovative 3D approach is used to develop and optimize structured polymeric fibrous materials. Using our own materials simulator we are able to design a new material with optimized properties such as porosity or thickness. In this work, for the first time we developed and tested a methodology to design a new fibrous material for which the penetration of a liquid drop can be predicted and optimized. The deposition of a liquid drop into a porous solid material is an important step in many materials applications like printing or filtration. The ability to control and predict the liquid kinetic deposition and the spreading area, are also determinant steps when developing new advanced materials, like structured porous materials, and new applications, like the transport of therapeutic molecules for medicinal purposes. We have used a methodology that includes an innovative 3D model for fibrous materials, an experimental plan to obtain 3D structures with different fibers, and an optic 3D prototype for collecting 3D data of the liquid drop deposition along time. We were able to quantify the time of deposition and the spreading area over time. Using the simulation model for fibrous materials we were able to simulate and produce in the laboratory an optimized structure for the ideal spreading area of the liquid droplet.
Joana M. R. Curto; António O. Mendes; Eduardo L. T. Conceição; Antonio Portugal; Paulo Fiadeiro; Ana Ramos; Rogerio Simoes; Manuel José Santos Silva. Development of an Innovative 3D Simulator for Structured Polymeric Fibrous Materials and Liquid Droplets. Advanced Structured Materials 2015, 301 -321.
AMA StyleJoana M. R. Curto, António O. Mendes, Eduardo L. T. Conceição, Antonio Portugal, Paulo Fiadeiro, Ana Ramos, Rogerio Simoes, Manuel José Santos Silva. Development of an Innovative 3D Simulator for Structured Polymeric Fibrous Materials and Liquid Droplets. Advanced Structured Materials. 2015; ():301-321.
Chicago/Turabian StyleJoana M. R. Curto; António O. Mendes; Eduardo L. T. Conceição; Antonio Portugal; Paulo Fiadeiro; Ana Ramos; Rogerio Simoes; Manuel José Santos Silva. 2015. "Development of an Innovative 3D Simulator for Structured Polymeric Fibrous Materials and Liquid Droplets." Advanced Structured Materials , no. : 301-321.
The use of eye gaze to formalize human visual system models and its use for QoE assessment is considered in this work. Typically the eye gaze defined by attention maps reveals difficult to be correlated with the perceived QoE. In this work attention maps of images with induced chromatic errors are obtained with an eye tracking device. Those attention maps are analyzed and compared with the MOS obtained from the subjective evaluation of the considered images.
Marco V. Bernardo; Antonio M. G. Pinheiro; Paulo T. Fiadeiro; Manuela Pereira; Bernardo M.V.; Pinheiro A.M.G.; Fiadeiro P.T.; Pereira M.. Eye gaze behavior under chromatic impairments and quality assessment. 2015 Seventh International Workshop on Quality of Multimedia Experience (QoMEX) 2015, 1 -6.
AMA StyleMarco V. Bernardo, Antonio M. G. Pinheiro, Paulo T. Fiadeiro, Manuela Pereira, Bernardo M.V., Pinheiro A.M.G., Fiadeiro P.T., Pereira M.. Eye gaze behavior under chromatic impairments and quality assessment. 2015 Seventh International Workshop on Quality of Multimedia Experience (QoMEX). 2015; ():1-6.
Chicago/Turabian StyleMarco V. Bernardo; Antonio M. G. Pinheiro; Paulo T. Fiadeiro; Manuela Pereira; Bernardo M.V.; Pinheiro A.M.G.; Fiadeiro P.T.; Pereira M.. 2015. "Eye gaze behavior under chromatic impairments and quality assessment." 2015 Seventh International Workshop on Quality of Multimedia Experience (QoMEX) , no. : 1-6.
A. De O. Mendes; P. T. Fiadeiro; A. P. Costa; M. E. Amaral; M. N. Belgacem. Laser scanning for assessment of the fiber anisotropy and orientation in the surfaces and bulk of the paper. Nordic Pulp & Paper Research Journal 2015, 30, 1 .
AMA StyleA. De O. Mendes, P. T. Fiadeiro, A. P. Costa, M. E. Amaral, M. N. Belgacem. Laser scanning for assessment of the fiber anisotropy and orientation in the surfaces and bulk of the paper. Nordic Pulp & Paper Research Journal. 2015; 30 (2):1.
Chicago/Turabian StyleA. De O. Mendes; P. T. Fiadeiro; A. P. Costa; M. E. Amaral; M. N. Belgacem. 2015. "Laser scanning for assessment of the fiber anisotropy and orientation in the surfaces and bulk of the paper." Nordic Pulp & Paper Research Journal 30, no. 2: 1.
Announcement of an iris and periocular dataset, with 10 different mobile setups.Mobile biometric recognition approach based on iris and periocular information.Improvements from a sensor-specific color calibration technique are reported.Biometric recognition feasibility over mobile cross-sensor setups is shown.Preferable mobile setups are pointed out. In recent years, the usage of mobile devices has increased substantially, as have their capabilities and applications. Extending biometric technologies to these gadgets is desirable because it would facilitate biometric recognition almost anytime, anywhere, and by anyone. The present study focuses on biometric recognition in mobile environments using iris and periocular information as the main traits. Our study makes three main contributions, as follows. (1) We demonstrate the utility of an iris and periocular dataset, which contains images acquired with 10 different mobile setups and the corresponding iris segmentation data. This dataset allows us to evaluate iris segmentation and recognition methods, as well as periocular recognition techniques. (2) We report the outcomes of device-specific calibration techniques that compensate for the different color perceptions inherent in each setup. (3) We propose the application of well-known iris and periocular recognition strategies based on classical encoding and matching techniques, as well as demonstrating how they can be combined to overcome the issues associated with mobile environments.
Gil Santos; Emanuel Grancho; Marco Bernardo; Paulo Fiadeiro. Fusing iris and periocular information for cross-sensor recognition. Pattern Recognition Letters 2015, 57, 52 -59.
AMA StyleGil Santos, Emanuel Grancho, Marco Bernardo, Paulo Fiadeiro. Fusing iris and periocular information for cross-sensor recognition. Pattern Recognition Letters. 2015; 57 ():52-59.
Chicago/Turabian StyleGil Santos; Emanuel Grancho; Marco Bernardo; Paulo Fiadeiro. 2015. "Fusing iris and periocular information for cross-sensor recognition." Pattern Recognition Letters 57, no. : 52-59.
Substantial efforts have been put into bridging the gap between biometrics and visual surveillance, in order to develop automata able to recognise human beings ‘in the wild’. This study focuses on biometric recognition in extremely degraded data, and its main contributions are three-fold: (1) announce the availability of an annotated dataset that contains high quality mugshots of 101 subjects, and large sets of probes degraded extremely by 10 different noise factors; (2) report the results of a mimicked watchlist identification scheme: an online survey was conducted, where participants were asked to perform positive and negative identification of probes against the enrolled identities. Along with their answers, volunteers had to provide the major reasons that sustained their responses, which enabled the authors to perceive the kind of features that are most frequently associated with successful/failed human identification processes. As main conclusions, the authors observed that humans rely greatly on shape information and holistic features. Otherwise, colour and texture-based features are almost disregarded by humans; (3) finally, the authors give evidence that the positive human identification on such extremely degraded data might be unreliable, whereas negative identification might constitute an interesting alternative for such cases.
Gil Santos; Paulo T. Fiadeiro; Hugo Proença. BioHDD: a dataset for studying biometric identification on heavily degraded data. IET Biometrics 2015, 4, 1 -9.
AMA StyleGil Santos, Paulo T. Fiadeiro, Hugo Proença. BioHDD: a dataset for studying biometric identification on heavily degraded data. IET Biometrics. 2015; 4 (1):1-9.
Chicago/Turabian StyleGil Santos; Paulo T. Fiadeiro; Hugo Proença. 2015. "BioHDD: a dataset for studying biometric identification on heavily degraded data." IET Biometrics 4, no. 1: 1-9.
This work addresses the study of repeatability of an optical laser system, previously implemented by our research team, for characterization of the fiber distribution and mass density of two paper samples with different characteristics. In the experiment that has been carried out in the current work, both paper samples were laser scanned by the system on a total of 16 times (4 times per day in 4 different days). The data acquired and registered during the experimental work, associated to both tested samples, were then processed and the obtained results showed that the optical system is precise.
António De O. Mendes; Paulo T. Fiadeiro; Ana Paula Costa; Maria Emília Amaral; Mohamed Naceur Belgacem. Study of repeatability of an optical laser system for characterization of the paper fiber distribution and mass density. Second International Conference on Applications of Optics and Photonics 2014, 9286, 92862Y .
AMA StyleAntónio De O. Mendes, Paulo T. Fiadeiro, Ana Paula Costa, Maria Emília Amaral, Mohamed Naceur Belgacem. Study of repeatability of an optical laser system for characterization of the paper fiber distribution and mass density. Second International Conference on Applications of Optics and Photonics. 2014; 9286 ():92862Y.
Chicago/Turabian StyleAntónio De O. Mendes; Paulo T. Fiadeiro; Ana Paula Costa; Maria Emília Amaral; Mohamed Naceur Belgacem. 2014. "Study of repeatability of an optical laser system for characterization of the paper fiber distribution and mass density." Second International Conference on Applications of Optics and Photonics 9286, no. : 92862Y.