Jaume Pujol

Polytechnic University of Catalonia, Barcino, Catalonia, Spain

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Publications (120)116.93 Total impact

  • No preview · Article · Nov 2015 · Applied Optics
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    ABSTRACT: To compare the static and dynamic accommodative responses measured with the WAM-5500 and the PowerRef-II autorefractors. The dynamic and static monocular accommodative responses were measured with the WAM-5500 and the PowerRef-II instruments in 30 pre-presbyopic patients (23.66 [±3.19] years). The spherical equivalent was measured at 0.00, 2.50, and 5.00 diopters (D) of accommodative stimulation for the static measurements. The subjective refraction was also determined. Dynamic accommodation was measured for abrupt changes of stimulus vergence of 2.00 D. Mean and peak velocities of accommodation and disaccommodation were evaluated. For the PowerRef-II, dynamic measurements were calculated for sampling frequencies of 5 and 25 Hz. For far distance static results, the differences between subjective and WAM-5500 measurements were 0.07 (±0.21) D (p = 0.093) and those between subjective and PowerRef-II measurements were 0.70 (±0.47) D (p = 0.001). The difference in the response measured with both instruments was 0.08 (±0.32) D (p = 0.194) for 2.50 D and -0.32 (±0.48) D (p = 0.001) for 5.00 D of stimulation. For the dynamic mode, the PowerRef-II at 25 Hz measured faster mean and peak velocities of accommodation and disaccommodation than the WAM-5500, with statistically significant (p < 0.05) differences of 0.68 (±1.01), 0.67 (±0.98), 1.26 (±1.19), and 1.42 (±1.53) D/s, respectively. With a sampling frequency of 5 Hz for the PowerRef-II, these differences, which were statistically significant (p < 0.05), were reduced to 0.52 (±0.90), 0.49 (±0.91), 0.83 (±1.07), and 0.83 (±1.31) D/s, respectively. There is good agreement between subjective refraction and WAM-5500 measurements. In contrast, the PowerRef-II produced more hyperopic results. There were no differences among instruments at 2.50 D of static stimulation; however, differences were found at 5.00 D. In the dynamic measurements, the PowerRef-II measured faster velocities, partly attributed to the difference in the sampling frequency.
    No preview · Article · Aug 2015 · Optometry and vision science: official publication of the American Academy of Optometry
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    ABSTRACT: Materials with new visual appearances have emerged over the last few years. In the automotive industry in particular there is a growing interest in materials with new effect finishes, such as metallic, pearlescent, sparkle, and graininess effects. Typically, for solid colours the mean of three measurements with repetitions is sufficient to obtain a representative measurement for colour characterisation. However, gonio‐apparent panels have non‐homogeneous colours, and there are no studies that recommend the minimum number of repetitions for colour, sparkle, and graininess characterisation of this type of panel. We assume that colour panels incorporating special‐effect pigments in their colour recipes will require a higher minimum number of measurements than solid colour panels. Therefore, the purpose of this study is to verify this assumption by using a multiangle BYK‐mac spectrophotometer, given that it is currently the only commercial device that can measure colour, sparkle, and graininess values simultaneously. In addition, a possible methodology is given for establishing the minimum number of measurements when characterising gonio‐apparent materials using a specific instrument, able to be implemented in future instruments when determining multiple appearance attributes (colour, gloss, sparkle, etc.) for many coloration technologies. Thus, we studied the minimum number of measurements needed to characterise the colour, sparkle, and graininess of three types of sample with solid, metallic, and pearlescent coatings respectively. Twenty measurements were made at twenty random positions (different target areas) of 90 samples. The minimum number of measurements for all these variables was determined on the basis of the point at which the cumulative mean value became constant. Thus, applying new statistical tools, it is clearly shown that metallic and pearlescent panels require more colour measurements than solid panels, in particular when geometries are being measured in a specular direction. As regards texture (sparkle and graininess), more measurements are needed for graininess than for sparkle, and more for metallic panels than for pearlescent panels.
    No preview · Article · Aug 2015 · Review of Progress in Coloration and Related Topics
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    ABSTRACT: The interest in gonioapparent pigments (metallic, pearlescent, interference, or diffractive) has increased in the last few years, especially for applications in the automotive industry. To assure a proper characterization of colors with gonioapparent pigments, commercial devices have appeared to characterize the color in different geometries, which are called multiangle spectrophotometers. As the gonioapparent pigments and multiangle instruments are relatively new, no studies exist regarding the instrumental-based procedure followed in the industry, and if the results provided are in agreement with the observer perception.Consequently, the main objective of this study was to examine the correlation of the instrumental color differences with visual assessments. The instrumental color difference was calculated with the color difference formula AUDI2000 (specific for this sector) between the pairs of similar samples of three types of coated panels (solid, metallic, and pearlescent). The values measured by a telespectroradiometer in a directional lighting booth and the colorimetric values obtained by means of a multiangle spectrophotometer BYK-mac were considered for this purpose. Additionally, a visual experiment was conducted to quantify the color difference by using the gray-scale method.The results revealed that an acceptable instrumental correlation existed despite the visual and the instrumental correlation being worse. In particular, it was checked that observers accepted a larger number of color pairs, that is, the visual color difference was smaller than the tolerance demanded by the industry (derived from AUDI2000). © 2015 Wiley Periodicals, Inc. Col Res Appl, 2015
    No preview · Article · Jun 2015 · Color Research & Application
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    ABSTRACT: To evaluate the usefulness of an infrared open-field autorefractor as a predictor of the refractive error when fitting multifocal contact lenses (MCL). Objective and subjective measurements of the non-cycloplegic distance refractive error were compared in patients wearing MCL. We used the Grand Seiko WAM-5500 autorefractor for the objective measurements. Three commercially available MCL were tested. Twenty-one eyes of sixteen healthy adults were included in the study. Over-refraction was evaluated in terms of spherical equivalent (SE) and astigmatic vectors (J0 and J45). The mean difference±SD of each parameter was calculated. The Kolmogorov-Smirnov test was used to verify the normal distribution. Pearson's correlation, Bland and Altman plot and paired sample t test were used to compare the results obtained with both methods. The mean difference between objective and subjective results of the SE over-refraction was 0.13±0.42D; for astigmatic vectors J0 and J45 were 0.03±0.32D and -0.00±0.17D, respectively. The Kolmogorov-Smirnov test showed a normal distribution for all parameters. The highest Pearson's correlation coefficients were obtained for the SE with values of 0.98 without MCL and 0.97 with MCL. The lowest were obtained for J45 with values of 0.65 without MCL and 0.75 with MCL. Significant correlations were obtained for each parameter. The paired sample t test failed to show significant differences in analyzed parameters except for J0 without MCL. The Grand Seiko WAM-5500 can be used as a screening method of over-refraction in the clinical fitting of MCL. Copyright © 2015 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.
    No preview · Article · Apr 2015 · Contact lens & anterior eye: the journal of the British Contact Lens Association
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    ABSTRACT: To evaluate intersession and intrasession repeatability of aberration data obtained with a new visual simulator based on adaptive optics, which includes a Hartmann-Shack aberrometer (Adaptive Optics Vision Analyzer; Voptica S.L., Murcia, Spain). Thirty-one healthy right eyes were included in the study. To evaluate intrasession repeatability, three consecutive measurements without repositioning the patient or realigning the eye were obtained. Intersession repeatability was evaluated in three sessions. Aberrometric data computed from the second to the fifth order for a 4-mm pupil were used. Statistical analysis included the repeated measures analysis of variance (or the Wilcoxon signed rank test), the coefficient of repeatability, the Bland-Altman method, and the intraclass correlation coefficient. No significant differences in the intrasession and intersession repeatability analysis for any of the parameters (P > .05) were found, suggesting a consistent variability of the instrument over time. Similar coefficient of repeatability values were obtained in the three sessions. The Bland-Altman analysis confirmed differences close to zero and the variations were independent of the mean within and between sessions. The intersession intraclass correlation coefficient values were generally above 0.75, suggesting moderate to high repeatability. However, some exceptions were found in the intrasession analysis. The findings suggest that the new instrument provides consistent and repeatable aberrometric data. It is therefore a suitable tool to perform consistent and repeatable visual simulations. [J Refract Surg. 2015;31(3):188-194.]. Copyright 2015, SLACK Incorporated.
    No preview · Article · Mar 2015 · Journal of refractive surgery (Thorofare, N.J.: 1995)
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    ABSTRACT: Speckle arises in double-pass images when coherent light is scattered by the retina. Since this noise degrades the images that are used to characterize the eye, there is special attention in reducing speckle when working with instruments based on retina reflections. In this work, we present a method for speckle reduction in double-pass retinal images by producing minor periodic variations in the vergence of the beam entering the eye with a variable-focus lens during image recording. Measurements in an artificial and a real eye following the implementation of the method corroborate the speckle reduction.
    Full-text · Article · Jan 2015 · Journal of the European Optical Society Rapid Publications
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    ABSTRACT: This study analyzes the repeatability, reproducibility and accuracy of a new hyperspectral system based on a pushbroom sensor as a means of measuring spectral features and color of materials and objects. The hyperspectral system consisted of a CCD camera, a spectrograph and an objective lens. An additional linear moving system allowed the mechanical scanning of the complete scene. A uniform overhead luminaire with daylight configuration was used to irradiate the scene using d:45 geometry. We followed the guidelines of the ASTM E2214-08 Standard Practice for Specifying and Verifying the Performance of Color-Measuring Instruments that define the standards and latest multidimensional procedures. The results obtained are analyzed in-depth and compared to those recently reported by other authors for spectrophotometers and multispectral systems. It can be concluded that hyperspectral systems are reliable and can be used in the industry to perform spectral and color readings with a high spatial resolution. © 2013 Wiley Periodicals, Inc. Col Res Appl, 2013
    No preview · Article · Dec 2014 · Color Research & Application
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    M Aldaba · A Giner · J Güell · J Pujol

    Full-text · Conference Paper · Sep 2014

  • No preview · Conference Paper · Aug 2014

  • No preview · Conference Paper · Aug 2014
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    A. Giner · M. Aldaba · M. Arjona · J. Pujol

    Full-text · Conference Paper · Aug 2014
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    ABSTRACT: The recent use of multispectral systems as a noncontact method for analysis of artworks has already shown promising results. This study explains the application of a novel portable multispectral system based on light-emitting diodes (LEDs) for artwork imaging. This method provides spectral information in a spectral range from 370 to 1630 nm with a 25 cm × 25 cm field of view by using two different image sensors in synchrony with 23 bands of irradiation. The spectral information for each point is estimated and validated using the pseudo-inverse and spline interpolation methods for spectral estimation and three different evaluation metrics. The results of the metrics obtained with both estimation methods show a general good performance of the system over the whole spectral range. The experiments also showed that the selection of the training set for the pseudo-inverse estimation has a great influence in its performance, and thus, it defines whether or not the pseudo-inverse outperforms the spline interpolation method. The system is applied in situ to the study of Catalan art masterpieces, and the results demonstrate the potential of a cost-effective and versatile system using various off-the-shelf elements to reconstruct color information and to reveal features not previously identified. © 2014 Wiley Periodicals, Inc. Col Res Appl, 2014
    No preview · Article · Aug 2014 · Color Research & Application
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    ABSTRACT: Purpose To evaluate the impact of contact lens (CL)-induced corneal swelling on the optical quality of the eye by means of the double-pass technique. Methods Measurements of 6 healthy subjects were obtained in 5 visits over 1 week, at baseline and after sleeping with 4 different CLs of +0.50 D, +2.00 D, +5.00 D and +8.00 D (Acuvue2), randomly fitted on 4 different days. The control eye wore no CL. Corneal pachymetry and optical quality of the eye (OQAS, Visiometrics) were measured once at baseline and at three interval times in the follow-up visits: immediately after CL removal, and 1 and 2 h after CL removal. Optical quality was evaluated by means of the Strehl ratio and OQAS values at 100%, 20% and 9% contrasts. Intraocular scattering was evaluated with the objective scatter index (OSI). Results Mean overnight swelling was 5.98 ± 4.29% in CL-eyes versus 0.30 ± 0.78% in control eyes (p < 0.01). Corneal swelling was maximal immediately after CL removal and decreased with time (p < 0.01). A significant worsening in all optical quality parameters and a significant increase of the OSI were found in eyes with corneal swelling (p < 0.05). Two hours after CL removal there were no statistically significant differences (p > 0.05) between CL-eyes and control eyes in any of the measured parameters. Conclusions Corneal swelling has a significant impact on the optical quality of the eye and on intraocular scattering as assessed with the double-pass technique.
    No preview · Article · Aug 2014 · Contact lens & anterior eye: the journal of the British Contact Lens Association
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    ABSTRACT: To expand and investigate the potential of spectral imaging, we developed a portable multispectral system using light-emitting diodes. This system recovers spectral information from the UV to the near IR over a large area using two different image sensors synchronized with 23 bands of illumination. The system was assessed for spectral reconstruction through simulations and experimental measurements by means of two methods of spectral reconstruction and three different evaluation metrics. The results over a Macbeth ColorChecker chart and other samples, including pigments usually employed in art paintings, are compared and discussed. The portable multispectral system using LEDs constitutes a cost-effective and versatile method for spectral imaging.
    No preview · Article · May 2014 · Applied Optics
  • J. Pujol · M. Aldaba · A. Giner · J. Arasa · S. Luque
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    ABSTRACT: Purpose: To assess the visual performance of a new multifocal intraocular lens design by means of a vision simulator Methods: We measured and compared the visual performance (VP) of a new multifocal intraocular lens (MIOL) design (NDIOL, OPHTEC prototype, Add=2D) a monofocal IOL (monIOL, used as a reference) and a commercial MIOL (MPlus, Oculentis® Add=+3D). To assess VP a vision simulator (VirtIOL, 101Lens S.L.U.) that projects the IOL in the pupil of the patients eye was used. VirtIOL allowed us to simulate vision through IOLs before surgery. LogMAR visual acuity (VA) and perception of halos in a throughfocus scanning from +1D to -4D, in 0.5D steps was tested using a pupil diameter of 4mm. The effect of IOL orientation error (3 positions with a change of 120 deg between them) and IOL positioning error (±0.5mm in both x and y axis) was also tested. All measurements were performed by the same operator and the same well trained observer in order to maintain the same criterion. Measurements were repeated 3 times showing similar results Results: In far vision (FV) the best VA was obtained for the monIOL(-0.2), followed by the Mplus(-0.1) and the NDIOL lens(0.0). In near vision (NV), the higher VA was obtained with the NDIOL(0.0) followed by Mplus(0.1), and the monIOL(0.4). No differences were found in the perception of halos between both MIOL lenses. The throughfocus scanning showed a bifocal lens behavior for the Mplus, this is, an accommodative curve with two well identified peaks of good VA in FV and NV and a VA decrease in intermediate distance(0.2). The NDIOL lens showed a nearly constant VA(0.0) for FV, intermediate and NV. The monIOL and NDIOL VA were unaffected by orientation, while Mplus VA was dependent on it. Positioning errors had no effect on the VA of the IOLs, except in Mplus when with a decentration of 0.5mm it had nearly a monofocal behavior due to the pupil is mainly covered by the FV zone of the lens Conclusions: VirtIOL allows assessing VP of IOL before surgery. The two MIOL lens analyzed showed a good VA performance for FV and NV. During the throughfocus scanning NDIOL lens had nearly constant VA values, while Mplus showed a bifocal lens behavior. NDIOL VA were unaffected by orientation, while Mplus VA was dependent on it. Mplus is more sensible to positioning errors due to pupil can be mainly covered by the FV. Further work with NDIOL will be developed to improve the VA values for FV
    No preview · Conference Paper · May 2014
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    ABSTRACT: Purpose: The aim of this article is to propose a quantitative methodology for determining a criterion to discriminate the nonsurgical nuclear cataract from the surgical one taking into account objective measures of intraocular scattering in patients with good visual acuity (>0.6). Methods: Two groups of subjects were taken into account: a control group and a group with nuclear cataracts. At a first stage, eyes belonging to the cataract group were classified into "nonsurgical" and "surgical" cataracts by ophthalmologists at their clinical settings. At a second stage a double-pass instrument was also used to determine the objective scatter index (OSI) at the laboratory. Receiver operating characteristic (ROC) curves were used to analyze OSI values to determine a value able to separate between nonsurgical and surgical cataracts. Results: We obtained statistically significant differences among the control and both nuclear cataract groups (p < 0.05). ROC curves determined an OSI criterion level (of 2.1) to suggest surgery in nuclear cataracts with an area under curve of 0.83, i.e. with 80% of sensitivity and 80% of specificity. Conclusions: ROC analysis allows separating both groups of nuclear cataract, and we determined a value of OSI in nuclear cataract quantification for surgery.
    Full-text · Article · Apr 2014 · Current eye research
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    ABSTRACT: Abstract: Purpose: To objectively estimate the intraocular scattering by means of a new index (Frecuency Scattering Index, FSI), which is computed by using the whole double-pass (DP) image. The index proposed takes into account the maximum variation of the slope of the modulation transfer function (MTF) obtained from the DP image recorded. Methods: We selected a group of 50 patients with different grades of nuclear cataracts, including from early to moderate stages according to the LOCS III classification system (from NO1 to NO3). A control group of 10 young normal eyes was also evaluated with the same procedure. DP images (size: 72 arc min) were obtained using a clinical instrument (OQAS, Visiometrics SL, Spain). From those images the FSI was computed by means of the corresponding MTF images and the analysis of their maximum slope. The FSI index was then compared with the OSI values (Objective Scatter Index) in terms of correlation. The OSI was provided by the OQAS instrument (Artal et al Plos 2011). The influence of low-order aberrations on the FSI was also analyzed by performing measurements on 8 healthy young subjects with induced defocus from -1.50 to +1.50 D in 0.25 D steps. These results were compared with those obtained by using the OSI parameter. Results: For the control group and patients with different cataract grades, a statistically significant correlation (r=0.726, p<0.001) was found between the FSI and LOCS III classification. Mean FSI (±SD) was of 0.49±0.12 for the control group; 1.86±1.02 for the NO1 group; 2.47±1.12 for the NO2 group; and 3.35±1.67 for the NO3 group. FSI and OSI values also showed a good and significant correlation (r =0.783, p<0.001). Furthermore, none of the 8 subjects with induced defocus showed a variation in the FSI index higher than 0.7 within the tested range. In the case of the OSI, the range within which that was accomplished was between -1.50 and +1.00 D (Martinez-Roda et al. Clin Exp Optom 2011). Conclusions: In this study a new index (FSI) to objectively estimate intraocular scattering by analyzing the slope variation in the MTF computed from the DP images is proposed. This index is computed using the complete DP image recorded and performs very well in discriminating different grades of nuclear cataracts. It has good correlations with the LOCS III clinical classification system and with the OSI parameter. FSI shows a high robustness regarding the induced defocus. Therefore, the FSI index could be a complementary and powerful tool in the objective assessment of intraocular scattering and thus for the improvement of cataract detection and surgery scheduling.
    Full-text · Dataset · Jan 2014
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    ABSTRACT: The technological fields where solid-state lighting can be applied are constantly growing. In relation to this topic, we built a spectral LED-based tuneable light source for the reconstruction of CIE standard illuminants. This light source consists of 31 spectral channels from 400nm to 700nm, an integrating cube and a control board with 16 bit resolution. Moreover, a minimization routine was developed to calculate the weighting values per channel for reproducing standard illuminants. The differences in colorimetric and fitting parameters between standard spectra and the theoretical and experimental ones, showed that the reconstructed spectra were very similar to the standard ones, specially for the D65 and A illuminants. However, there was a certain mismatching from 500nm to 600nm due to the lack of LEDs in this region. In conclusion, the developed LED-based light source and minimization routine are able to reproduce CIE standard illuminants with high accuracy.
    No preview · Article · Jan 2014
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    ABSTRACT: To evaluate the accuracy of spherical equivalent (SE) estimates of a double-pass system and to compare it with retinoscopy, subjective refraction and a table-mounted autorefractor. Non-cycloplegic refraction was performed on 125 eyes of 65 healthy adults (age 23.5±3.0 years) from October 2010 to January 2011 using retinoscopy, subjective refraction, autorefraction (Auto kerato-refractometer TOPCON KR-8100, Japan) and a double-pass system (Optical Quality Analysis System, OQAS, Visiometrics S.L., Spain). Nine consecutive measurements with the double-pass system were performed on a subgroup of 22 eyes to assess repeatability. To evaluate the trueness of the OQAS instrument, the SE laboratory bias between the double-pass system and the other techniques was calculated. The SE mean coefficient of repeatability obtained was 0.22D. Significant correlations could be established between the OQAS and the SE obtained with retinoscopy (r=0.956, P<0.001), subjective refraction (r=0.955, P<0.001) and autorefraction (r=0.957, P<0.001). The differences in SE between the double-pass system and the other techniques were significant (P<0.001), but lacked clinical relevance except for retinoscopy; Retinoscopy gave more hyperopic values than the double-pass system -0.51±0.50D as well as the subjective refraction -0.23±0.50D; More myopic values were achieved by means of autorefraction 0.24±0.49D. The double-pass system provides accurate and reliable estimates of the SE that can be used for clinical studies. This technique can determine the correct focus position to assess the ocular optical quality. However, it has a relatively small measuring range in comparison with autorefractors (-8.00 to +5.00D), and requires prior information on the refractive state of the patient.
    No preview · Article · Nov 2013 · International Journal of Ophthalmology

Publication Stats

971 Citations
116.93 Total Impact Points


  • 1989-2015
    • Polytechnic University of Catalonia
      • • CD6 - Centre for Sensors, Instruments and Systems Development
      • • Department of Optics and Optometry (OO)
      • • Department of Physics and Nuclear Engineering (FEN)
      Barcino, Catalonia, Spain
  • 2012
    • Institut Marqués, Spain, Barcelona
      Barcino, Catalonia, Spain
  • 1988-2012
    • Universitat Oberta de Catalunya
      Barcino, Catalonia, Spain
    • Escola Universitària Politècnica
      Terrassa, Catalonia, Spain
  • 2011
    • Hospital Universitario Virgen de la Arrixaca
      Murcia, Murcia, Spain
  • 2006
    • Universidad Politécnica de Cartagena
      Carthago Nova, Murcia, Spain
  • 2000
    • University of Alicante
      • Optics, Pharmacology and Anatomy
      Alicante, Valencia, Spain
  • 1991
    • Physikalisch-Technische Bundesanstalt
      • Department 2.4 Quantum Electronics
      Brunswyck, Lower Saxony, Germany