Publications Jean-Baptiste Thomas research

Jean-Baptiste Thomas

 

Color and multispectral imaging and computational appearance

Mamuntisunio, el photonius - Jalium calaniluitus

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Thomas J-B, Hardeberg JY, Foucherot I and Gouton P (2008), "The PLVC display color characterization model revisited", Color Research & Application. Vol. 33(6), pp. 449-460. Wiley Subscription Services, Inc., A Wiley Company.
Abstract: This work proposes a study of the Piecewise Linear assuming Variation in Chromaticity (PLVC) display color characterization model. This model has not been widely used as the improved accuracy compared with the more common PLCC (Piecewise Linear assuming Chromaticity Constancy) model is not significant for CRT (Cathode Ray Tube) display technology, and it requires more computing power than this model. With today's computers, computational complexity is less of a problem, and today's display technologies show a different colorimetric behavior than CRTs. The main contribution of this work is to generalize the PLVC model to multiprimary displays and to provide extensive experimental results and analysis for today's display technologies. We confirm and extend the results found in the literature and compare this model with classical PLCC and Gain-Offset-Gamma-Offset models. We show that using this model is highly beneficial for Liquid Crystal Displays, reducing the average error about a third for the two tested LCD projectors compared with a black corrected PLCC model, from 3.93 and 1.78 to respectively 1.41 and 0.54 ΔE *ab units. © 2008 Wiley Periodicals, Inc. Col Res Appl, 33, 449–460, 2008
BibTeX:
@article{2008CRA,
  author = {Thomas, Jean-Baptiste and Hardeberg, Jon Y. and Foucherot, Irène and Gouton, Pierre},
  title = {The PLVC display color characterization model revisited},
  journal = {Color Research & Application},
  publisher = {Wiley Subscription Services, Inc., A Wiley Company},
  year = {2008},
  volume = {33},
  number = {6},
  pages = {449--460},
  url = {http://jbthomas.org/Journals/2008CRA.pdf},
  doi = {10.1002/col.20447}
}
Thomas J-B, Colantoni P, Hardeberg JY, Foucherot I and Gouton P (2008), "A geometrical approach for inverting display color-characterization models", Journal of the Society for Information Display. Vol. 16(10), pp. 1021-1031. Blackwell Publishing Ltd.
Abstract: Abstract— Some display color-characterization models are not easily inverted. This work proposes ways to build geometrical inverse models given any forward color-characterization model. The main contribution is to propose and analyze several methods to optimize the 3-D geometrical structure of an inverse color-characterization model directly based on the forward model. Both the amount of data and their distribution in color space is especially focused on. Several optimization criteria, related either to an evaluation data set or to the geometrical structure itself, are considered. A practical case with several display devices, combining the different methods proposed in the article, are considered and analyzed.
BibTeX:
@article{2008JSID,
  author = {Thomas, Jean-Baptiste and Colantoni, Philippe and Hardeberg, Jon Y. and Foucherot, Ire`ne and Gouton, Pierre},
  title = {A geometrical approach for inverting display color-characterization models},
  journal = {Journal of the Society for Information Display},
  publisher = {Blackwell Publishing Ltd},
  year = {2008},
  volume = {16},
  number = {10},
  pages = {1021--1031},
  url = {http://jbthomas.org/Journals/2008JSID.pdf},
  doi = {10.1889/JSID16.10.1021}
}
Thomas J-B, Bakke A and Gerhardt J (2010-05-01T00:00:00), "Spatial Nonuniformity of Color Features in Projection Displays: A Quantitative Analysis", Journal of Imaging Science and Technology. Vol. 54(3), pp. 30403-1-30403-13.
Abstract: In this article, the authors investigate and study the color spatial uniformity of projectors. A common assumption in previous works is to consider that only the luminance is varying along the spatial dimensions. The authors show that the chromaticity plays a significant role in the
spatial color shift and should not be disregarded depending on the application. The authors base their conclusions on the measurements obtained from three projectors. First, two methods are used to analyze the spatial properties of the projectors, a conventional approach, and a new one that
considers three-dimensional gamut differences. The results show that the color gamut difference between two spatial coordinates within the same display can be larger than the difference observed between two projectors. In a second part, the authors focus on the evaluation of assumptions commonly
made in projector color characterization. The authors investigate if these assumptions are still valid along the spatial dimensions. Features studied include normalized response curve, chromaticity constancy of primaries, and channel independence. Some features seem to vary noticeably spatially,
such as the normalized response curve. Some others appear to be quite invariant, such as the channel independence.
BibTeX:
@article{2010JIST,
  author = {Thomas, Jean-Baptiste and Bakke, Arne and Gerhardt, Jeremie},
  title = {Spatial Nonuniformity of Color Features in Projection Displays: A Quantitative Analysis},
  journal = {Journal of Imaging Science and Technology},
  year = {2010-05-01T00:00:00},
  volume = {54},
  number = {3},
  pages = {30403-1-30403-13},
  url = {http://jbthomas.org/Journals/2010JIST.pdf},
  doi = {10.2352/J.ImagingSci.Technol.2010.54.3.030403}
}
Colantoni P, Thomas J-B and Hardeberg JY (2011), "High-end colorimetric display characterization using an adaptive training set", Journal of the Society for Information Display. Vol. 19(8), pp. 520-530. Blackwell Publishing Ltd.
Abstract: Abstract— A new, accurate, and technology-independent display color-characterization model is introduced. It is based on polyharmonic spline interpolation and on an optimized adaptive training data set. The establishment of this model is fully automatic and requires only a few minutes, making it efficient in a practical situation. The experimental results are very good for both the forward and inverse models. Typically, the proposed model yields an average model prediction error of about 1 ΔEab* unit or below for several displays. The maximum error is shown to be low as well.
BibTeX:
@article{2011JSID,
  author = {Colantoni, Philippe and Thomas, Jean-Baptiste and Hardeberg, Jon Y.},
  title = {High-end colorimetric display characterization using an adaptive training set},
  journal = {Journal of the Society for Information Display},
  publisher = {Blackwell Publishing Ltd},
  year = {2011},
  volume = {19},
  number = {8},
  pages = {520--530},
  url = {http://jbthomas.org/Journals/2011JSID.pdf},
  doi = {10.1889/JSID19.8.520}
}
Wang X, Thomas J-B, Hardeberg JY and Gouton P (2014), "Multispectral imaging: narrow or wide band filters?", Journal of the International Colour Association. Vol. 12, pp. 44-51.
Abstract: Abstract— In every aspect, spectral characteristics of filters play an important role in an image acquisition
system. For a colorimetric system, traditionally, it is believed that narrow-band filters give rise to
higher accuracy of colour reproduction, whereas wide-band filters, such as complementary colour
filters, have the advantage of higher sensitivity. In the context of multispectral image capture, the
objective is very often to retrieve an estimation of the spectral reflectance of the captured objects. The
literature does not provide a satisfactory answer to which configuration yields the best results. It is
therefore of interest to verify which type of filters performs the best in estimating the reflectance
spectra for the purpose of multispectral image acquisition. A series of experiments were conducted on
a simulated imaging system, with six types of filters of varying bandwidths paired with three linear
reflectance estimation methods. The results show that filter bandwidth exerts direct influence on the
accuracy of reflectance estimation. Extremely narrowband filters did not perform well in the
experiment and the relation between bandwidth and reflectance estimation accuracy is not monotonic.
Also it is indicated that the optimal number of filters depends on the spectral similarity metrics
employed.
BibTeX:
@article{2014JAIC,
  author = {Wang, Xingbo and Thomas, Jean-Baptiste and Hardeberg, Jon Yngve and Gouton, Pierre},
  editor = {International Colour Association},
  title = {Multispectral imaging: narrow or wide band filters?},
  journal = {Journal of the International Colour Association},
  year = {2014},
  volume = {12},
  pages = {44--51},
  note = {eng},
  url = {http://jbthomas.org/Journals/2014JAIC.pdf}
}
Lapray P-J, Wang X, Thomas J-B and Gouton P (2014), "Multispectral Filter Arrays: Recent Advances and Practical Implementation", Sensors. Vol. 14(11), pp. 21626.
Abstract: Thanks to some technical progress in interferencefilter design based on different technologies, we can finally successfully implement the concept of multispectral filter array-based sensors. This article provides the relevant state-of-the-art for multispectral imaging systems and presents the characteristics of the elements of our multispectral sensor as a case study. The spectral characteristics are based on two different spatial arrangements that distribute eight different bandpass filters in the visible and near-infrared area of the spectrum. We demonstrate that the system is viable and evaluate its performance through sensor spectral simulation.
BibTeX:
@article{2014Sensors,
  author = {Lapray, Pierre-Jean and Wang, Xingbo and Thomas, Jean-Baptiste and Gouton, Pierre},
  title = {Multispectral Filter Arrays: Recent Advances and Practical Implementation},
  journal = {Sensors},
  year = {2014},
  volume = {14},
  number = {11},
  pages = {21626},
  url = {http://jbthomas.org/Journals/2014Sensors.pdf},
  doi = {10.3390/s141121626}
}
Zhao P, Pedersen M, Hardeberg JY and Thomas J-B (2015-05-01T00:00:00), "Measuring the Relative Image Contrast of Projection Displays", Journal of Imaging Science and Technology. Vol. 59(3), pp. 30404-1-30404-13.
Abstract:
Abstract
Projection displays, compared to other modern display technologies, have many unique advantages. However, the image quality assessment of projection displays has not been well studied so far. In this paper, we propose an objective approach to measure the relative
contrast of projection displays based on the pictures taken with a calibrated digital camera in a dark room where the projector is the only light source. A set of carefully selected natural images is modified to generate multiple levels of image contrast. In order to enhance the validity,
reliability, and robustness of our research, we performed the experiments in similar viewing conditions at two separate geographical locations with different projection displays. In each location, we had a group of observers to give perceptual ratings. Further, we adopted state-of-art contrast
measures to evaluate the relative contrast of the acquired images. The experimental results suggest that the Michelson contrast measure performs the worst, as expected, while other global contrast measures perform relatively better, but they have less correlation with the perceptual ratings
than local contrast measures. The local contrast measures perform better than global contrast measures for all test images, but all contrast measures failed on the test images with low luminance or dominant colors and without texture areas. In addition, the high correlations between the experimental
results for the two projections displays indicate that our proposed assessment approach is valid, reliable, and consistent.
BibTeX:
@article{2015JIST,
  author = {Zhao, Ping and Pedersen, Marius and Hardeberg, Jon Yngve and Thomas, Jean-Baptiste},
  title = {Measuring the Relative Image Contrast of Projection Displays},
  journal = {Journal of Imaging Science and Technology},
  year = {2015-05-01T00:00:00},
  volume = {59},
  number = {3},
  pages = {30404-1-30404-13},
  url = {http://jbthomas.org/Journals/2015JIST.pdf},
  doi = {10.2352/J.ImagingSci.Technol.2015.59.3.030404}
}
Colantoni P, Thomas J-B and Trémeau A (2016), "Sampling CIELAB color space with perceptual metrics", International Journal of Imaging and Robotics. Vol. 16(3), pp. xx-xx.
Abstract:
Abstract
Sampling a perceptually uniform or pseudo-uniform color space is required for applications
from image processing to computational imaging. However, one can face two problems
while trying to perform a uniform sampling of such space. First, the usual cubic grid is not
perceptually uniform in most cases. Second, perceptual metrics are often not Euclidean.
We propose to overcome these problems. We apply our solution on CIELAB color space
to test its efficiency. We propose an algorithm to define a tabulated color space with regard
to a non-Euclidean color difference formula, i.e. DE00 in CIELAB. The tabulated data are
available at http://data.couleur.org/deltaE/. Later, we propose to combine this
tabulated color space with an approximated 3D close packed hexagonal regular sampling
of CIELAB. Evaluations of the transform and of the regular sampling are performed and
compared with literature standards.
BibTeX:
@article{2016IJIR,
  author = {Colantoni, Philippe and Thomas, Jean-Baptiste and Trémeau, Alain},
  title = {Sampling CIELAB color space with perceptual metrics},
  journal = {International Journal of Imaging and Robotics},
  year = {2016},
  volume = {16},
  number = {3},
  pages = {xx-xx},
  url = {http://jbthomas.org/Journals/2016IJIR.pdf}
}
Pedersen M, Suazo D and Thomas J-B (2016), "Seam-Based Edge Blending for Multi-Projection Systems", International Journal of Signal Processing, Image Processing and Pattern Recognition. Vol. 9(4), pp. 11-26.
Abstract:
Abstract
Perceptual seamlessness of large-scale tiled displays is still a challenge. One way to
avoid Bezel effects from contiguous displays is to blend superimposed parts of the image
over the edges. This work proposes a new approach for edge blending. It is based on
intensity edge blending adapted on the seam description of the image content. The main
advantage of this method is to reduce visual artifacts thanks to context adaptation and
smooth transitions. We evaluate the quality of the method with a perceptual experiment
where it is compared with state-of-the-art methods. The new method shows most improvement in low frequency areas compared to the other techniques. This method can be inserted into any multi-projector system that already applies edge blending.
BibTeX:
@article{2016IJISP,
  author = {Pedersen, Marius and Suazo, Daniel and Thomas, Jean-Baptiste},
  title = {Seam-Based Edge Blending for Multi-Projection Systems},
  journal = {International Journal of Signal Processing, Image Processing and Pattern Recognition},
  year = {2016},
  volume = {9},
  number = {4},
  pages = {11-26},
  url = {http://jbthomas.org/Journals/2016IJSIP.pdf},
  doi = {10.14257/ijsip.2016.9.4.02}
}
Thomas J-B, Lapray P-J, Gouton P and Clerc C (2016), "Spectral Characterization of a Prototype SFA Camera for Joint Visible and NIR Acquisition", Sensors. Vol. 16(7), pp. 993.
Abstract: Multispectral acquisition improves machine vision since it permits capturing more information on object surface properties than color imaging. The concept of spectral filter arrays has been developed recently and allows multispectral single shot acquisition with a compact camera design. Due to filter manufacturing difficulties, there was, up to recently, no system available for a large span of spectrum, i.e., visible and Near Infra-Red acquisition. This article presents the achievement of a prototype of camera that captures seven visible and one near infra-red bands on the same sensor chip. A calibration is proposed to characterize the sensor, and images are captured. Data are provided as supplementary material for further analysis and simulations. This opens a new range of applications in security, robotics, automotive and medical fields.
BibTeX:
@article{2016Sensors,
  author = {Thomas, Jean-Baptiste and Lapray, Pierre-Jean and Gouton, Pierre and Clerc, Cédric},
  title = {Spectral Characterization of a Prototype SFA Camera for Joint Visible and NIR Acquisition},
  journal = {Sensors},
  year = {2016},
  volume = {16},
  number = {7},
  pages = {993},
  url = {http://jbthomas.org/Journals/2016Sensors.pdf},
  doi = {10.3390/s16070993}
}
Lapray P-J, Thomas J-B, Gouton P and Ruichek Y (2017), "Energy balance in Spectral Filter Array camera design", Journal of the European Optical Society-Rapid Publications., jan, 2017. Vol. 13(1) Springer Nature.
BibTeX:
@article{2017JEOS,
  author = {Pierre-Jean Lapray and Jean-Baptiste Thomas and Pierre Gouton and Yassine Ruichek},
  title = {Energy balance in Spectral Filter Array camera design},
  journal = {Journal of the European Optical Society-Rapid Publications},
  publisher = {Springer Nature},
  year = {2017},
  volume = {13},
  number = {1},
  url = {http://jbthomas.org/Journals/2017JEOS.pdf},
  doi = {10.1186/s41476-016-0031-7}
}
Khan HA, Thomas J-B, Hardeberg JY and Laligant O (2017), "Illuminant estimation in multispectral imaging", J. Opt. Soc. Am. A., Jul, 2017. Vol. 34(7), pp. 1085-1098. OSA.
Abstract: With the advancement in sensor technology, the use of multispectral imaging is gaining wide popularity for computer vision applications. Multispectral imaging is used to achieve better discrimination between the radiance spectra, as compared to the color images. However, it is still sensitive to illumination changes. This study evaluates the potential evolution of illuminant estimation models from color to multispectral imaging. We first present a state of the art on computational color constancy and then extend a set of algorithms to use them in multispectral imaging. We investigate the influence of camera spectral sensitivities and the number of channels. Experiments are performed on simulations over hyperspectral data. The outcomes indicate that extension of computational color constancy algorithms from color to spectral gives promising results and may have the potential to lead towards efficient and stable representation across illuminants. However, this is highly dependent on spectral sensitivities and noise. We believe that the development of illuminant invariant multispectral imaging systems will be a key enabler for further use of this technology.
BibTeX:
@article{2017JOSAA,
  author = {Haris Ahmad Khan and Jean-Baptiste Thomas and Jon Yngve Hardeberg and Olivier Laligant},
  title = {Illuminant estimation in multispectral imaging},
  journal = {J. Opt. Soc. Am. A},
  publisher = {OSA},
  year = {2017},
  volume = {34},
  number = {7},
  pages = {1085--1098},
  url = {http://jbthomas.org/Journals/2017JOSAA.pdf},
  doi = {10.1364/JOSAA.34.001085}
}
Lapray P-J, Thomas J-B and Gouton P (2017), "High Dynamic Range Spectral Imaging Pipeline For Multispectral Filter Array Cameras", Sensors. Vol. 17(6), pp. 1281.
Abstract: Spectral filter arrays imaging exhibits a strong similarity with color filter arrays. This permits us to embed this technology in practical vision systems with little adaptation of the existing solutions. In this communication, we define an imaging pipeline that permits high dynamic range (HDR)-spectral imaging, which is extended from color filter arrays. We propose an implementation of this pipeline on a prototype sensor and evaluate the quality of our implementation results on real data with objective metrics and visual examples. We demonstrate that we reduce noise, and, in particular we solve the problem of noise generated by the lack of energy balance. Data are provided to the community in an image database for further research.
BibTeX:
@article{2017Sensors,
  author = {Lapray, Pierre-Jean and Thomas, Jean-Baptiste and Gouton, Pierre},
  title = {High Dynamic Range Spectral Imaging Pipeline For Multispectral Filter Array Cameras},
  journal = {Sensors},
  year = {2017},
  volume = {17},
  number = {6},
  pages = {1281},
  url = {http://jbthomas.org/Journals/2017Sensors.pdf},
  doi = {10.3390/s17061281}
}
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CONFERENCES:

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Thomas J-B and Tremeau A (2007), "A Gamut Preserving Color Image Quantization", In Image Analysis and Processing Workshops, 2007. ICIAPW 2007. 14th International Conference on., Sept, 2007. , pp. 221-226.
Abstract: We propose a new approach for color image quantization which preserves the shape of the color gamut of the studied image. Quantization consists to find a set of color representative of the color distribution of the image. We are looking here for an optimal LUT (look up table) which contains information on the image's gamut and on the color distribution of this image. The main motivation of this work is to control the reproduction of color images on different output devices in order to have the same color feeling, coupling intrinsic informations on the image gamut and output device calibration. We have developped a color quantization algorithm based on an image dependant sampling of the CIELAB color space. This approach overcomes classical approaches.
BibTeX:
@inproceedings{2007CCIW,
  author = {Thomas, Jean-Baptiste and Tremeau, Alain},
  title = {A Gamut Preserving Color Image Quantization},
  booktitle = {Image Analysis and Processing Workshops, 2007. ICIAPW 2007. 14th International Conference on},
  year = {2007},
  pages = {221-226},
  url = {http://jbthomas.org/Conferences/2007CCIW.pdf},
  doi = {10.1109/ICIAPW.2007.6}
}
Thomas J-B, Chareyron G and Trémeau A (2007), "Image watermarking based on a color quantization process", Proc. SPIE. Vol. 6506, pp. 650603-650603-12.
Abstract: The purpose of this paper is to propose a color image watermarking scheme based on an image dependent color gamut sampling of the L*a*b* color space. The main motivation of this work is to control the reproduction of color images on different output devices in order to have the same color feeling, coupling intrinsic informations on the image gamut and output device calibration. This paper is focused firstly on the research of an optimal LUT (Look Up Table) which both circumscribes the color gamut of the studied image and samples the color distribution of this image. This LUT is next embedded in the image as a secret message. The principle of the watermarking scheme is to modify the pixel value of the host image without causing any change neither in image appearance nor on the shape of the image gamut.
BibTeX:
@inproceedings{2007EI,
  author = {Thomas, Jean-Baptiste and Chareyron, Gael and Trémeau, Alain},
  title = {Image watermarking based on a color quantization process},
  journal = {Proc. SPIE},
  year = {2007},
  volume = {6506},
  pages = {650603-650603-12},
  url = {http://jbthomas.org/Conferences/2007EI.pdf},
  doi = {10.1117/12.702010}
}
Thomas J-B, Hardeberg J, Foucherot I and Gouton P (2007), "Additivity Based LC Display Color Characterization", GCIS'07. (2), pp. 50-55.
Abstract: PLVC model.
BibTeX:
@inproceedings{2007GCIS,
  author = {Thomas, Jean-Baptiste and Hardeberg, Jon and Foucherot, Irene and Gouton, Pierre},
  title = {Additivity Based LC Display Color Characterization},
  journal = {GCIS'07},
  year = {2007},
  number = {2},
  pages = {50-55},
  url = {http://jbthomas.org/Conferences/2007GCIS.pdf}
}
Mikalsen EB, Hardeberg JY and Thomas J-B (2008-01-01T00:00:00), "Verification and extension of a camera-based end-user calibration method for projection displays", Conference on Colour in Graphics, Imaging, and Vision. Vol. 2008(1), pp. 575-579.
Abstract: We evaluate, analyse and propose improvements to a previously published end-user calibration method for projection devices (Bala and Braun, CIC 2006). We focus on the estimation of the displays tone response curve, using only an uncalibrated consumercamera. The results show that the
method is accurate, depending on both the projector and the camera used. We found that the method is accurate enough for most end-user applications. A weakness of this method is the wrong estimation of the projectors black level, which significantly affects the estimation of the camera response
curve.
BibTeX:
@article{2008CGIV,
  author = {Mikalsen, Espen Bårdsnes and Hardeberg, Jon Y. and Thomas, Jean-Baptiste},
  title = {Verification and extension of a camera-based end-user calibration method for projection displays},
  journal = {Conference on Colour in Graphics, Imaging, and Vision},
  year = {2008-01-01T00:00:00},
  volume = {2008},
  number = {1},
  pages = {575-579},
  url = {http://jbthomas.org/Conferences/2008CGIV.pdf}
}
Thomas J-B, Colantoni P, Hardeberg JY, Foucherot I and Gouton P (2008), "An inverse display color characterization model based on an optimized geometrical structure", Proc. SPIE. Vol. 6807, pp. 68070A-68070A-12.
Abstract: We have defined an inverse model for colorimetric characterization of additive displays. It is based on an optimized three-dimensional tetrahedral structure. In order to minimize the number of measurements, the structure is defined using a forward characterization model. Defining a regular grid in the device-dependent destination color space leads to heterogeneous interpolation errors in the device-independent source color space. The parameters of the function used to define the grid are optimized using a globalized Nelder-Mead simplex downhill algorithm. Several cost functions are tested on several devices. We have performed experiments with a forward model which assumes variation in chromaticities (PLVC), based on one-dimensional interpolations for each primary ramp along X, Y and Z (3×3×1-D ). Results on 4 devices (2 LCD and a DLP projection devices, one LCD monitor) are shown and discussed.
BibTeX:
@inproceedings{2008EI,
  author = {Thomas, Jean-Baptiste and Colantoni, Philippe and Hardeberg, Jon Y. and Foucherot, Irène and Gouton, Pierre},
  title = {An inverse display color characterization model based on an optimized geometrical structure},
  journal = {Proc. SPIE},
  year = {2008},
  volume = {6807},
  pages = {68070A-68070A-12},
  url = {http://jbthomas.org/Conferences/2008EI.pdf},
  doi = {10.1117/12.766487}
}
Thomas J-B and Bakke AM (2009), "Computational Color Imaging: Second International Workshop, CCIW 2009, Saint-Etienne, France, March 26-27, 2009. Revised Selected Papers" Berlin, Heidelberg , pp. 160-169. Springer Berlin Heidelberg.
BibTeX:
@inproceedings{2009CCIW,
  author = {Thomas, Jean-Baptiste and Bakke, Arne Magnus},
  editor = {Trémeau, Alain and Schettini, Raimondo and Tominaga, Shoji},
  title = {Computational Color Imaging: Second International Workshop, CCIW 2009, Saint-Etienne, France, March 26-27, 2009. Revised Selected Papers},
  publisher = {Springer Berlin Heidelberg},
  year = {2009},
  pages = {160--169},
  url = {http://jbthomas.org/Conferences/2009CCIW.pdf},
  doi = {10.1007/978-3-642-03265-3_17}
}
Bakke AM, Thomas J-B and Gerhardt J (2009), "Common assumptions in color characterization of projectors", GCIS'09. (3), pp. 50-55.
Abstract: Projection system spatial uniformity.
BibTeX:
@inproceedings{2009GCIS,
  author = {Bakke, Arne Magnus and Thomas, Jean-Baptiste and Gerhardt, Jeremie},
  title = {Common assumptions in color characterization of projectors},
  journal = {GCIS'09},
  year = {2009},
  number = {3},
  pages = {50-55},
  url = {http://jbthomas.org/Conferences/2009GCIS.pdf}
}
Colantoni P and Thomas J-B (2009), "Image Analysis: 16th Scandinavian Conference, SCIA 2009, Oslo, Norway, June 15-18, 2009. Proceedings" Berlin, Heidelberg , pp. 128-137. Springer Berlin Heidelberg.
BibTeX:
@inproceedings{2009SCIA,
  author = {Colantoni, Philippe and Thomas, Jean-Baptiste},
  editor = {Salberg, Arnt-Børre and Hardeberg, Jon Yngve and Jenssen, Robert},
  title = {Image Analysis: 16th Scandinavian Conference, SCIA 2009, Oslo, Norway, June 15-18, 2009. Proceedings},
  publisher = {Springer Berlin Heidelberg},
  year = {2009},
  pages = {128--137},
  url = {http://jbthomas.org/Conferences/2009SCIA.pdf},
  doi = {10.1007/978-3-642-02230-2_14}
}
Gerhardt J and Thomas J-B (2010-01-01T00:00:00), "Toward an automatic color calibration for 3D displays", Color and Imaging Conference. Vol. 2010(1), pp. 5-10.
Abstract: This article considers the color correction of a 3D projection display installation. The system consists of a pair of projectors of the same model modified by INFITECGmbH such that they can be used for projection of 3D contents. The goal of this color correction is to reduce
the difference between the two mo-dified projectors such as the color difference between them does not disturb the user. Two new approaches are proposed and compared with the Infitec expert correction. One is based on an objective colorimetric match, the other on the optimization of a transform
considering the color difference between the two signals.
BibTeX:
@article{2010CIC,
  author = {Gerhardt, Jeremie and Thomas, Jean-Baptiste},
  title = {Toward an automatic color calibration for 3D displays},
  journal = {Color and Imaging Conference},
  year = {2010-01-01T00:00:00},
  volume = {2010},
  number = {1},
  pages = {5-10},
  url = {http://jbthomas.org/Conferences/2010CIC.pdf}
}
Thomas J-B (2010), "Controlling color in display: A discussion on quality", CREATE.
Abstract: Display and Quality
BibTeX:
@article{2010CREATE,
  author = {Thomas, Jean-Baptiste},
  title = {Controlling color in display: A discussion on quality},
  journal = {CREATE},
  year = {2010},
  url = {http://jbthomas.org/Conferences/2010CREATE.pdf}
}
Colantoni P, Thomas J-B and Pillay R (2010), "Graph-based 3D Visualization of Color Content in Paintings", In VAST: International Symposium on Virtual Reality, Archaeology and Intelligent Cultural Heritage - Short and Project Papers. The Eurographics Association.
BibTeX:
@incollection{2010VAST,
  author = {Colantoni, Philippe and Thomas, Jean-Baptiste and Pillay, Ruven},
  editor = {Alessandro Artusi and Morwena Joly and Genevieve Lucet and Denis Pitzalis and Alejandro Ribes},
  title = {Graph-based 3D Visualization of Color Content in Paintings},
  booktitle = {VAST: International Symposium on Virtual Reality, Archaeology and Intelligent Cultural Heritage - Short and Project Papers},
  publisher = {The Eurographics Association},
  year = {2010},
  url = {http://jbthomas.org/Conferences/2010VAST.pdf},
  doi = {10.2312/PE/VAST/VAST10S/025-030}
}
Thomas J-B and Boust C (2011-01-01T00:00:00), "Colorimetric Characterization of a Positive Film Scanner Using an Extremely Reduced Training Data Set", Color and Imaging Conference. Vol. 2011(1), pp. 152-155.
Abstract: In this work, we address the problem of having an accurate colorimetric characterization of a scanner for traditional positive film in order to guarantee the accuracy of the color information during the digitization of a movie. The scanning of a positive film is not an usual task, however
it can happen for cultural heritage purpose. Art-movies, are often created and stored as positive-film in museums. One of the problems one can face for a colorimetric characterization is to have a reasonable number of measurements from an item. In this work we succeeded in having a reasonable
accuracy with just a few number of measurement (typically 4 to 7 E*ab units with 2 to less than 10 measurements).
BibTeX:
@article{2011CIC,
  author = {Thomas, Jean-Baptiste and Boust, Clotilde},
  title = {Colorimetric Characterization of a Positive Film Scanner Using an Extremely Reduced Training Data Set},
  journal = {Color and Imaging Conference},
  year = {2011-01-01T00:00:00},
  volume = {2011},
  number = {1},
  pages = {152-155},
  url = {http://jbthomas.org/Conferences/2011CIC.pdf}
}
Thomas J-B and Gerhardt J (2012-01-01T00:00:00), "Webcam based display calibration", Color and Imaging Conference. Vol. 2012(1), pp. 82-87.
Abstract: We present an automatic method for measuring the tone response curve of display devices based on visual methods, where the eye is replaced by an end-user, uncalibrated camera, such as a webcam. Our approach compares a series of halftoned patches of known covering ratio with a continuous
series of tone patches for each ratio. Both patches are shot by a camera that is used as a virtual eye to evaluate the luminance difference. By an iterative process, the continuous tone value is adjusted while compared with the perceived level of the halftoned patch. When the camera does not
see any difference between the patches or a minimal difference, the luminance level of the continuous patch corresponds to the relative luminance of the halftoned patch covering ratio. We demonstrate that the method is as accurate as an equivalent visual method. The advantage of using a camera
over the human eye is due to the limitation of observer variability while performing visual tasks.
BibTeX:
@article{2012CIC,
  author = {Thomas, Jean-Baptiste and Gerhardt, Jeremie},
  title = {Webcam based display calibration},
  journal = {Color and Imaging Conference},
  year = {2012-01-01T00:00:00},
  volume = {2012},
  number = {1},
  pages = {82-87},
  url = {http://jbthomas.org/Conferences/2012CIC.pdf}
}
Wang X, Thomas J-B, Hardeberg JY and Gouton P (2013), "A Study on the Impact of Spectral Characteristics of Filters on Multispectral Image Acquisition", In Proceedings of AIC Colour 2013. Gateshead, Royaume-Uni, July, 2013. Vol. 4, pp. 1765-1768.
Abstract: In every aspect, filter design plays an important role in an image acquisition system based on a single image sensor and a colour filter array (CFA) mounted onto the sensor. Complementary CFAs are used by some colour cameras in the interest of higher sensitivity, which motivated us to employ filters of wide pass bands in the effort to adapt CFA for multispectral image acquisition. In this context, filter design has an effect on the accuracy of spectrum reconstruction in addition to other aspects. The results show that wider bandwidths in general result in more faithful spectrum reconstruction and higher signal-to-noise performance.
BibTeX:
@inproceedings{2013AIC,
  author = {Wang, Xingbo and Thomas, Jean-Baptiste and Hardeberg, Jon Yngve and Gouton, Pierre},
  editor = {Lindsay MacDonald, Stephen Westland, Sophie Wuerger},
  title = {A Study on the Impact of Spectral Characteristics of Filters on Multispectral Image Acquisition},
  booktitle = {Proceedings of AIC Colour 2013},
  year = {2013},
  volume = {4},
  pages = {1765-1768},
  url = {http://jbthomas.org/Conferences/2013AIC.pdf}
}
Thomas J-B, Colantoni P and Trémeau A (2013), "Computational Color Imaging: 4th International Workshop, CCIW 2013, Chiba, Japan, March 3-5, 2013. Proceedings" Berlin, Heidelberg , pp. 53-67. Springer Berlin Heidelberg.
BibTeX:
@inbook{2013CCIW,
  author = {Thomas, Jean-Baptiste and Colantoni, Philippe and Trémeau, Alain},
  editor = {Tominaga, Shoji and Schettini, Raimondo and Trémeau, Alain},
  title = {Computational Color Imaging: 4th International Workshop, CCIW 2013, Chiba, Japan, March 3-5, 2013. Proceedings},
  publisher = {Springer Berlin Heidelberg},
  year = {2013},
  pages = {53--67},
  url = {http://jbthomas.org/Conferences/2013CCIW.pdf},
  doi = {10.1007/978-3-642-36700-7_5}
}
Peguillet H, Thomas J-B, Gouton P and Ruichek Y (2013), "Energy balance in single exposure multispectral sensors", In Colour and Visual Computing Symposium (CVCS), 2013., Sept, 2013. , pp. 1-6.
Abstract: Recent simulations of multispectral sensors are based on a simple Gaussian model, which includes filters transmittance and substrate absorption. In this paper we want to make the distinction between these two layers. We discuss the balance of energy by channel in multispectral solid state sensors and propose an updated simple Gaussian model to simulate multispectral sensors. Results are based on simulation of typical sensor configurations.
BibTeX:
@inproceedings{2013CVCSa,
  author = {Peguillet, Hugues and Thomas, Jean-Baptiste and Gouton, Pierre and Ruichek, Yassine},
  title = {Energy balance in single exposure multispectral sensors},
  booktitle = {Colour and Visual Computing Symposium (CVCS), 2013},
  year = {2013},
  pages = {1-6},
  url = {http://jbthomas.org/Conferences/2013aCVCS.pdf},
  doi = {10.1109/CVCS.2013.6626277}
}
Wang X, Thomas J-B, Hardeberg J and Gouton P (2013), "Discrete wavelet transform based multispectral filter array demosaicking", In Colour and Visual Computing Symposium (CVCS), 2013., Sept, 2013. , pp. 1-6.
Abstract: The idea of colour filter array may be adapted to multispectral image acquisition by integrating more filter types into the array, and developing associated demosaicking algorithms. Several methods employing discrete wavelet transform (DWT) have been proposed for CFA demosaicking. In this work, we put forward an extended use of DWT for multispectral filter array demosaicking. The extension seemed straightforward, however we observed striking results. This work contributes to better understanding of the issue by demonstrating that spectral correlation and spatial resolution of the images exerts a crucial influence on the performance of DWT based demosaicking.
BibTeX:
@inproceedings{2013CVCSb,
  author = {Xingbo Wang and Thomas, J.-B. and Hardeberg, J.Y. and Gouton, P.},
  title = {Discrete wavelet transform based multispectral filter array demosaicking},
  booktitle = {Colour and Visual Computing Symposium (CVCS), 2013},
  year = {2013},
  pages = {1-6},
  url = {http://jbthomas.org/Conferences/2013bCVCS.pdf},
  doi = {10.1109/CVCS.2013.6626274}
}
Wang X, Thomas J-B, Hardeberg JY and Gouton P (2013), "Median filtering in multispectral filter array demosaicking", Proc. SPIE. Vol. 8660, pp. 86600E-86600E-10.
Abstract: Inspired by the concept of the colour filter array (CFA), the research community has shown much interest in
adapting the idea of CFA to the multispectral domain, producing multispectral filter arrays (MSFAs). In addition
to newly devised methods of MSFA demosaicking, there exists a wide spectrum of methods developed for CFA.
Among others, some vector based operations can be adapted naturally for multispectral purposes. In this paper,
we focused on studying two vector based median filtering methods in the context of MSFA demosaicking. One
solves demosaicking problems by means of vector median filters, and the other applies median filtering to the
demosaicked image in spherical space as a subsequent refinement process to reduce artefacts introduced by
demosaicking. To evaluate the performance of these measures, a tool kit was constructed with the capability
of mosaicking, demosaicking and quality assessment. The experimental results demonstrated that the vector
median filtering performed less well for natural images except black and white images, however the refinement
step reduced the reproduction error numerically in most cases. This proved the feasibility of extending CFA
demosaicking into MSFA domain.
BibTeX:
@inproceedings{2013EI,
  author = {Wang, Xingbo and Thomas, Jean-Baptiste and Hardeberg, Jon Y. and Gouton, Pierre},
  title = {Median filtering in multispectral filter array demosaicking},
  journal = {Proc. SPIE},
  year = {2013},
  volume = {8660},
  pages = {86600E-86600E-10},
  url = {http://jbthomas.org/Conferences/2013EI.pdf},
  doi = {10.1117/12.2005256}
}
Zhao P, Pedersen M, Hardeberg JY and Thomas J-B (2013), "Camera-based measurement of relative image contrast in projection displays", In Visual Information Processing (EUVIP), 2013 4th European Workshop on., June, 2013. , pp. 112-117.
Abstract: This research investigated the measured contrast of projection displays based on pictures taken by un-calibrated digital cameras under typical viewing conditions. A high-end radiometer was employed as a reference to the physical response of projection luminance. Checkerboard, gray scale and color complex test images with a range of the projector's brightness and contrast settings were projected. Two local and two global contrast metrics were evaluated on the acquired pictures. We used contrast surface plots and Pearson correlation to investigate the measured contrast versus the projector's brightness and contrast settings. The results suggested, as expected, the projector contrast has a more significant impact on measured contrast than projector brightness, but the measured contrast based on either camera or radiometer has a nonlinear relationship with projector settings. The results also suggested that simple statistics based metrics might produce a higher Pearson correlation value with both projector contrast and projector brightness than more complex contrast metrics. Our results demonstrated that the rank order of un-calibrated camera based measured contrast and radiometer based measured contrast is preserved for large steps of projector setting differences.
BibTeX:
@inproceedings{2013EUVIP,
  author = {Zhao, Ping and Pedersen, Marius and Hardeberg, Jon Yngve and Thomas, Jean-Baptiste},
  title = {Camera-based measurement of relative image contrast in projection displays},
  booktitle = {Visual Information Processing (EUVIP), 2013 4th European Workshop on},
  year = {2013},
  pages = {112-117},
  url = {http://jbthomas.org/Conferences/2013EUVIP.pdf}
}
Zhao P, Pedersen M, Thomas J-B and Hardeberg JY (2014-11-03T00:00:00), "Perceptual Spatial Uniformity Assessment of Projection Displays with a Calibrated Camera", Color and Imaging Conference. Vol. 2014(2014), pp. 159-164.
Abstract: Spatial uniformity is one of the most important image quality attributes in visual experience of displays. In conventional researches, spatial uniformity was mostly measured with a radiometer and its quality was assessed with non-reference image quality metrics. Cameras are cheaper
than radiometers and they can provide accurate relative measurements if they are carefully calibrated. In this paper, we propose and implement a work-flow to use a calibrated camera as a relative acquisition device of intensity to measure the spatial uniformity of projection displays. The
camera intensity transfer functions for every projected pixels are recovered, so we can produce multiple levels of linearized non-uniformity on the screen in the purpose of image quality assessment. The experiment results suggest that our work-flow works well. Besides, none of the frequently
referred uniformity metrics correlate well with the perceptual results for all types of test images. The spatial non-uniformity is largely masked by the high frequency components in the displayed image content, and we should simulate the human visual system to ignore the non-uniformity that
cannot be discriminated by human observers. The simulation can be implemented using models based on contrast sensitivity functions, contrast masking, etc.
BibTeX:
@article{2014CICa,
  author = {Zhao, Ping and Pedersen, Marius and Thomas, Jean-Baptiste and Hardeberg, Jon Yngve},
  title = {Perceptual Spatial Uniformity Assessment of Projection Displays with a Calibrated Camera},
  journal = {Color and Imaging Conference},
  year = {2014-11-03T00:00:00},
  volume = {2014},
  number = {2014},
  pages = {159-164},
  url = {http://jbthomas.org/Conferences/2014aCIC.pdf}
}
Lapray P-J, Thomas J-B and Gouton P (2014-11-03T00:00:00), "A Multispectral Acquisition System using MSFAs", Color and Imaging Conference. Vol. 2014(2014), pp. 97-102.
Abstract: Thanks to technical progress in interferential filter design, we can finally implement in practice the concept of Multispectral Filter Array based sensors. This article presents the characteristics of the elements of our sensor as a case study. The spectral characteristics are based
on two different spatial arrangements that distribute eight different bandpass filters in the visible and near-infrared area of the spectrum. We demonstrate that the system is viable and evaluate its performance through sensor spectral simulation and characterization.
BibTeX:
@article{2014CICb,
  author = {Lapray, Pierre-Jean and Thomas, Jean-Baptiste and Gouton, Pierre},
  title = {A Multispectral Acquisition System using MSFAs},
  journal = {Color and Imaging Conference},
  year = {2014-11-03T00:00:00},
  volume = {2014},
  number = {2014},
  pages = {97-102},
  url = {http://jbthomas.org/Conferences/2014bCIC.pdf}
}
El Khoury J, Thomas J-B and Alamin M (2014), "Does Dehazing Model Preserve Color Information?", In Signal-Image Technology and Internet-Based Systems (SITIS), 2014 Tenth International Conference on., Nov, 2014. , pp. 606-613.
Abstract: Image dehazing aims at estimating the image information lost caused by the presence of fog, haze and smoke in the scene during acquisition. Degradation causes a loss in contrast and color information, thus enhancement becomes an inevitable task in imaging applications and consumer photography. Color information has been mostly evaluated perceptually along with quality, but no work adresses specifically this aspect. We demonstrate how dehazing model affects color information on simulated and real images. We use a convergence model from perception of transparency to simulate haze on images. We evaluate color loss in terms of angle of hue in IPT color space, saturation in CIE LUV color space and perceived color difference in CIE LAB color space. Results indicate that saturation is critically changed and hue is changed for achromatic colors and blue/yellow colors, where usual image processing space are not showing constant hue lines. We suggest that a correction model based on color transparency perception could help to retrieve color information as an additive layer on dehazing algorithms.
BibTeX:
@inproceedings{2014COMI,
  author = {El Khoury, Jessica and Thomas, Jean-Baptiste and Mansouri Alamin},
  title = {Does Dehazing Model Preserve Color Information?},
  booktitle = {Signal-Image Technology and Internet-Based Systems (SITIS), 2014 Tenth International Conference on},
  year = {2014},
  pages = {606-613},
  url = {http://jbthomas.org/Conferences/2014CoMI.pdf},
  doi = {10.1109/SITIS.2014.78}
}
Wang X, Pedersen M and Thomas J-B (2014), "The influence of chromatic aberration on demosaicking", In Visual Information Processing (EUVIP), 2014 5th European Workshop on., Dec, 2014. , pp. 1-6.
Abstract: The wide deployment of colour imaging devices owes much to the use of colour filter array (CFA). A CFA produces a mosaic image, and normally a subsequent CFA demosaicking algorithm interpolates the mosaic image and estimates the full-resolution colour image. Among various types of optical aberrations from which a mosaic image may suffer, chromatic aberration (CA) influences the spatial and spectral correlation through the artefacts such as blur and mis-registration, which demosaicking also relies on. In this paper we propose a simulation framework aimed at an investigation of the influence of CA on demosaicking. Results show that CA benefits demosaicking to some extent, however CA lowers the quality of resulting images by any means.
BibTeX:
@inproceedings{2014EUVIP,
  author = {Wang, Xingbo and Pedersen, Marius and Thomas, Jean-Baptiste},
  title = {The influence of chromatic aberration on demosaicking},
  booktitle = {Visual Information Processing (EUVIP), 2014 5th European Workshop on},
  year = {2014},
  pages = {1-6},
  url = {http://jbthomas.org/Conferences/2014EUVIP.pdf},
  doi = {10.1109/EUVIP.2014.7018410}
}
Zhao P, Pedersen M, Hardeberg JY and Thomas JB (2014), "Image registration for quality assessment of projection displays", In 2014 IEEE International Conference on Image Processing (ICIP)., Oct, 2014. , pp. 3488-3492.
Abstract: In the full reference metric based image quality assessment of projection displays, it is critical to achieve accurate and fully automatic image registration between the captured projection and its reference image in order to establish a subpixel level mapping. The preservation of geometrical order as well as the intensity and chromaticity relationships between two consecutive pixels must be maximized. The existing camera based image registration methods do not meet this requirement well. In this paper, we propose a markerless and view independent method to use an un-calibrated camera to perform the task. The proposed method including three main components: feature extraction, feature expansion and geometric correction, and it can be implemented easily in a fully automatic fashion. The experimental results of both simulation and the one conducted in the field demonstrate that the proposed method is able to achieve image registration accuracy higher than 91% in a dark projection room and above 85% with ambient light lower than 30 Lux.
BibTeX:
@inproceedings{2014ICIP,
  author = {P. Zhao and M. Pedersen and J. Y. Hardeberg and J. B. Thomas},
  title = {Image registration for quality assessment of projection displays},
  booktitle = {2014 IEEE International Conference on Image Processing (ICIP)},
  year = {2014},
  pages = {3488-3492},
  url = {http://jbthomas.org/Conferences/2014ICIP.pdf},
  doi = {10.1109/ICIP.2014.7025708}
}
Benezeth Y, Sidibé D and Thomas J-B (2014), "Background subtraction with multispectral video sequences", In IEEE International Conference on Robotics and Automation workshop on Non-classical Cameras, Camera Networks and Omnidirectional Vision (OMNIVIS). , pp. 6-p.
Abstract: Motion analysis of moving targets is an important
issue in several applications such as video surveillance or robotics.
Background subtraction is one of the simplest and widely used
techniques for moving target detection in video sequences. In
this paper, we investigate the advantages of using a multispectral
video acquisition system of more than three bands for background
subtraction over the use of trichromatic or monochromatic
video sequences. To this end, we have established a dataset of
multispectral videos with a manual annotation of moving objects.
To the best of our knowledge, this is the first publicly available
dataset of multispectral video sequences. Experimental results
indicate that using more than three spectral sub-bands provide
better discrimination between foreground and background pixels.
In particular, the use of the near infra-red (NIR) spectral band
together with visible spectra provides the best results.
BibTeX:
@inproceedings{2014OMNIVIS,
  author = {Benezeth, Yannick and Sidibé, Désiré and Thomas, Jean-Baptiste},
  title = {Background subtraction with multispectral video sequences},
  booktitle = {IEEE International Conference on Robotics and Automation workshop on Non-classical Cameras, Camera Networks and Omnidirectional Vision (OMNIVIS)},
  year = {2014},
  pages = {6--p},
  url = {http://jbthomas.org/Conferences/2014OMNIVIS.pdf}
}
El Khoury J, Thomas J-B and Mansouri A (2015), "Haze and convergence models: Experimental comparison", In AIC 2015. Tokyo, Japan, May, 2015.
BibTeX:
@inproceedings{2015AIC,
  author = {El Khoury, Jessica and Thomas, Jean-Baptiste and Mansouri, Alamin},
  title = {Haze and convergence models: Experimental comparison},
  booktitle = {AIC 2015},
  year = {2015},
  url = {http://jbthomas.org/Conferences/2015AIC.pdf}
}
Wang X, Green PJ, Thomas J-B, Hardeberg JY and Gouton P (2015), "Computational Color Imaging: 5th International Workshop, CCIW 2015, Saint Etienne, France, March 24-26, 2015, Proceedings" Cham , pp. 181-191. Springer International Publishing.
BibTeX:
@inbook{2015CCIW,
  author = {Wang, Xingbo and Green, Philip J. and Thomas, Jean-Baptiste and Hardeberg, Jon Y. and Gouton, Pierre},
  editor = {Trémeau, Alain and Schettini, Raimondo and Tominaga, Shoji},
  title = {Computational Color Imaging: 5th International Workshop, CCIW 2015, Saint Etienne, France, March 24-26, 2015, Proceedings},
  publisher = {Springer International Publishing},
  year = {2015},
  pages = {181--191},
  url = {http://jbthomas.org/Conferences/2015CCIW.pdf},
  doi = {10.1007/978-3-319-15979-9_18}
}
Zhao P, Pedersen M, Hardeberg JY and Thomas J-B (2015-10-18T00:00:00), "Measuring the Relative Image Contrast of Projection Displays", Color and Imaging Conference. Vol. 2015(1), pp. 79-91.
Abstract: Projection displays, compared to other modern display technologies, have many unique advantages. However, the image quality assessment of projection displays has not been well studied so far. In this paper, we propose an objective approach to measure the relative contrast of projection
displays based on the pictures taken with a calibrated digital camera in a dark room where the projector is the only light source. A set of carefully selected natural images is modified to generate multiple levels of image contrast. In order to enhance the validity, reliability, and robustness
of our research, we performed the experiments in similar viewing conditions at two separate geographical locations with different projection displays. In each location, we had a group of observers to give perceptual ratings. Further, we adopted state-of-art contrast measures to evaluate the
relative contrast of the acquired images. The experimental results suggest that the Michelson contrast measure performs the worst, as expected, while other global contrast measures perform relatively better, but they have less correlation with the perceptual ratings than local contrast measures.
The local contrast measures perform better than global contrast measures for all test images, but all contrast measures failed on the test images with low luminance or dominant colors and without texture areas. In addition, the high correlations between the experimental results for the two
projections displays indicate that our proposed assessment approach is valid, reliable, and consistent. c 2015 Society for Imaging Science and Technology.
BibTeX:
@article{2015CIC,
  author = {Zhao, Ping and Pedersen, Marius and Hardeberg, Jon Yngve and Thomas, Jean-Baptiste},
  title = {Measuring the Relative Image Contrast of Projection Displays},
  journal = {Color and Imaging Conference},
  year = {2015-10-18T00:00:00},
  volume = {2015},
  number = {1},
  pages = {79-91},
  url = {http://jbthomas.org/Journals/2015JIST.pdf}
}
Thomas J-B (2015), "Illuminant estimation from uncalibrated multispectral images", In Colour and Visual Computing Symposium (CVCS), 2015., Aug, 2015. , pp. 1-6.
Abstract: We investigate the physical validity of typical computational color constancy models for illuminant estimation of uncalibrated multispectral images. We demonstrate empirically that the assumptions may be reasonable and that we retrieve reasonably well the illumination for some images. On these images, we also have access to a good estimate of the spectral properties of the illumination while increasing the number of bands. However, some other images do not provide a very good illuminant estimation. We also show that the result depends mostly on the scene, rather than on the hypothesis made or on the number of spectral bands. Besides, the influence of the algorithm and its hypothesis is more critical for more bands than for the 3 - D color case.
BibTeX:
@inproceedings{2015CVCS,
  author = {Thomas, Jean-Baptiste},
  title = {Illuminant estimation from uncalibrated multispectral images},
  booktitle = {Colour and Visual Computing Symposium (CVCS), 2015},
  year = {2015},
  pages = {1-6},
  url = {http://jbthomas.org/Conferences/2015CVCS.pdf},
  doi = {10.1109/CVCS.2015.7274900}
}
Sadeghipoor Z, Thomas J-B and Susstrunk S (2016-11-03T00:00:00), "Demultiplexing visible and Near-Infrared Information in single-sensor multispectral imaging", Color and Imaging Conference. Vol. 2016(2016), pp. xx-xx.
Abstract: SFA
BibTeX:
@article{2016CIC,
  author = {Sadeghipoor, Zahra and Thomas, Jean-Baptiste and Susstrunk, Sabine},
  title = {Demultiplexing visible and Near-Infrared Information in single-sensor multispectral imaging},
  journal = {Color and Imaging Conference},
  year = {2016-11-03T00:00:00},
  volume = {2016},
  number = {2016},
  pages = {xx-xx},
  url = {http://jbthomas.org/Conferences/2016CIC.pdf}
}
El Khoury J, Thomas J-B and Mansouri A (2016), "A Color Image Database for Haze Model and Dehazing Methods Evaluation", In Image and Signal Processing: 7th International Conference, ICISP 2016, Trois-Rivières, QC, Canada, May 30 - June 1, 2016, Proceedings. Cham , pp. 109-117. Springer International Publishing.
BibTeX:
@inbook{2016ICISP,
  author = {El Khoury, Jessica and Thomas, Jean-Baptiste and Mansouri, Alamin},
  editor = {Mansouri, Alamin and Nouboud, Fathallah and Chalifour, Alain and Mammass, Driss and Meunier, Jean and Elmoataz, Abderrahim},
  title = {A Color Image Database for Haze Model and Dehazing Methods Evaluation},
  booktitle = {Image and Signal Processing: 7th International Conference, ICISP 2016, Trois-Rivières, QC, Canada, May 30 - June 1, 2016, Proceedings},
  publisher = {Springer International Publishing},
  year = {2016},
  pages = {109--117},
  url = {http://jbthomas.org/Conferences/2016MCS.pdf},
  doi = {10.1007/978-3-319-33618-3_12}
}
Lapray P-J, Thomas J-B and Gouton P (2017), "A Database of Spectral Filter Array Images that Combine Visible and NIR", In Computational Color Imaging: 6th International Workshop, CCIW 2017, Milan, Italy, March 29-31, 2017, Proceedings. Cham , pp. 187-196. Springer International Publishing.
BibTeX:
@inbook{2017aCCIW,
  author = {Lapray, Pierre-Jean and Thomas, Jean-Baptiste and Gouton, Pierre},
  editor = {Bianco, Simone and Schettini, Raimondo and Trémeau, Alain and Tominaga, Shoji},
  title = {A Database of Spectral Filter Array Images that Combine Visible and NIR},
  booktitle = {Computational Color Imaging: 6th International Workshop, CCIW 2017, Milan, Italy, March 29-31, 2017, Proceedings},
  publisher = {Springer International Publishing},
  year = {2017},
  pages = {187--196},
  url = {http://jbthomas.org/Conferences/2017aCCIW.pdf},
  doi = {10.1007/978-3-319-56010-6_16}
}
Thomas J-B, Lapray P-J and Gouton P (2017), "HDR Imaging Pipeline for Spectral Filter Array Cameras", In Image Analysis: 20th Scandinavian Conference, SCIA 2017, Tromsø, Norway, June 12--14, 2017, Proceedings, Part II. Cham , pp. 401-412. Springer International Publishing.
BibTeX:
@inbook{2017aSCIA,
  author = {Thomas, Jean-Baptiste and Lapray, Pierre-Jean and Gouton, Pierre},
  editor = {Sharma, Puneet and Bianchi, Filippo Maria},
  title = {HDR Imaging Pipeline for Spectral Filter Array Cameras},
  booktitle = {Image Analysis: 20th Scandinavian Conference, SCIA 2017, Tromsø, Norway, June 12--14, 2017, Proceedings, Part II},
  publisher = {Springer International Publishing},
  year = {2017},
  pages = {401--412},
  url = {http://jbthomas.org/Conferences/2017aSCIA.pdf},
  doi = {10.1007/978-3-319-59129-2_34}
}
Khan HA, Thomas J-B and Hardeberg JY (2017), "Analytical Survey of Highlight Detection in Color and Spectral Images", In Computational Color Imaging: 6th International Workshop, CCIW 2017, Milan, Italy, March 29-31, 2017, Proceedings. Cham , pp. 197-208. Springer International Publishing.
BibTeX:
@inbook{2017bCCIW,
  author = {Khan, Haris Ahmad and Thomas, Jean-Baptiste and Hardeberg, Jon Yngve},
  editor = {Bianco, Simone and Schettini, Raimondo and Trémeau, Alain and Tominaga, Shoji},
  title = {Analytical Survey of Highlight Detection in Color and Spectral Images},
  booktitle = {Computational Color Imaging: 6th International Workshop, CCIW 2017, Milan, Italy, March 29-31, 2017, Proceedings},
  publisher = {Springer International Publishing},
  year = {2017},
  pages = {197--208},
  url = {http://jbthomas.org/Conferences/2017bCCIW.pdf},
  doi = {10.1007/978-3-319-56010-6_17}
}
Khan HA, Thomas JB and Hardeberg JY (2017), "Multispectral Constancy Based on Spectral Adaptation Transform", In Image Analysis: 20th Scandinavian Conference, SCIA 2017, Tromsø, Norway, June 12--14, 2017, Proceedings, Part II. Cham , pp. 459-470. Springer International Publishing.
BibTeX:
@inbook{2017bSCIA,
  author = {Khan, Haris Ahmad and Thomas, Jean Baptiste and Hardeberg, Jon Yngve},
  editor = {Sharma, Puneet and Bianchi, Filippo Maria},
  title = {Multispectral Constancy Based on Spectral Adaptation Transform},
  booktitle = {Image Analysis: 20th Scandinavian Conference, SCIA 2017, Tromsø, Norway, June 12--14, 2017, Proceedings, Part II},
  publisher = {Springer International Publishing},
  year = {2017},
  pages = {459--470},
  url = {http://jbthomas.org/Conferences/2017bSCIA.pdf},
  doi = {10.1007/978-3-319-59129-2_39}
}
Thomas J-B, Hardeberg JY and Simone G (2017), "Image Contrast Measure as a Gloss Material Descriptor", In Computational Color Imaging: 6th International Workshop, CCIW 2017, Milan, Italy, March 29-31, 2017, Proceedings. Cham , pp. 233-245. Springer International Publishing.
BibTeX:
@inbook{2017cCCIW,
  author = {Thomas, Jean-Baptiste and Hardeberg, Jon Yngve and Simone, Gabriele},
  editor = {Bianco, Simone and Schettini, Raimondo and Trémeau, Alain and Tominaga, Shoji},
  title = {Image Contrast Measure as a Gloss Material Descriptor},
  booktitle = {Computational Color Imaging: 6th International Workshop, CCIW 2017, Milan, Italy, March 29-31, 2017, Proceedings},
  publisher = {Springer International Publishing},
  year = {2017},
  pages = {233--245},
  url = {http://jbthomas.org/Conferences/2017cCCIW.pdf},
  doi = {10.1007/978-3-319-56010-6_20}
}
Ansari K, Thomas J-B and Gouton P (2017), "Spectral band Selection Using a Genetic Algorithm Based Wiener Filter Estimation Method for Reconstruction of Munsell Spectral Data", Electronic Imaging. Vol. 2017(18), pp. 190-193.
Abstract: Spectrophotometers are the common devices for reflectance measurements. However, there are some drawbacks associated with these devices. Price, sample size and physical state are the main difficulties in applying them for reflectance measurement. Spectral estimation using a set of camera-filters
is the eligibly solution for avoiding these difficulties. Meanwhile band selection of filters are needed to be optimized in order to apply in imaging systems. In the present study, the Genetic algorithm was applied for finding the best set of three to eight filters combinations with specific
FWHM. The algorithm tries to minimize the color difference between reconstructed and actual spectral data, assuming a simulation of imaging system. This imaging system is composed of a CMOS sensor, illuminant and 1269 matt Munsell spectral data set as the object. All simulations were done
in visible spectrum. The optimized filter selections were modeled on a CMOS sensor in order to spectral reflectance reconstruction. The results showed no significant improvement after selecting a seven filter set although a descending trend in the color difference errors was obtained with
increasing the number of filters.
BibTeX:
@article{2017EI,
  author = {Ansari, Keivan and Thomas, Jean-Baptiste and Gouton, Pierre},
  title = {Spectral band Selection Using a Genetic Algorithm Based Wiener Filter Estimation Method for Reconstruction of Munsell Spectral Data},
  journal = {Electronic Imaging},
  year = {2017},
  volume = {2017},
  number = {18},
  pages = {190-193},
  url = {http://jbthomas.org/Conferences/2017EI.pdf},
  doi = {10.2352/ISSN.2470-1173.2017.18.COLOR-059}
}
Created by JabRef on 21/06/2017.

BOOKS:

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Thomas J-B, Hardeberg J and Trémeau A (2013), "Cross-Media Color Reproduction and Display Characterization", In Advanced Color Image Processing and Analysis. , pp. 81-118. Springer New York.
BibTeX:
@incollection{ThomasBook2013a,
  author = {Thomas, Jean-Baptiste and Hardeberg, JonY. and Trémeau, Alain},
  editor = {Fernandez-Maloigne, Christine},
  title = {Cross-Media Color Reproduction and Display Characterization},
  booktitle = {Advanced Color Image Processing and Analysis},
  publisher = {Springer New York},
  year = {2013},
  pages = {81-118},
  url = {http://dx.doi.org/10.1007/978-1-4419-6190-7_4},
  doi = {10.1007/978-1-4419-6190-7_4}
}
Nozick V and Thomas J-B (2013), "Calibration et Rectification", In Vidéo 3D., October, 2013. , pp. 105-124. Hermès.
BibTeX:
@inbook{ThomasBook2013b,
  author = {Vincent Nozick and Jean-Baptiste Thomas},
  editor = {Laurent Lucas, Celine Loscos and Yannick REMION},
  title = {Calibration et Rectification},
  booktitle = {Vidéo 3D},
  publisher = {Hermès},
  year = {2013},
  pages = {105-124},
  url = {http://hal-upec-upem.archives-ouvertes.fr/hal-00844453}
}
Nozick V and Thomas J-B (2013), "Camera Calibration: Geometric and Colorimetric Correction", In 3D Video. , pp. 91-112. John Wiley & Sons, Inc..
Abstract: This chapter analyzes camera calibration from a geometric and colorimetric perspective. The first part of the chapter introduces the mathematical model that describes a camera such as position, orientation, focal, as well as its applications such as 3D reconstructions. It analyzes different geometric processes for stereoscopic images such as corrections of radial distortion as well as image rectification. The second part of the chapter focuses on colorimetric models relating to digital acquisition systems. It demonstrates how to characterize a colorimetric camera and then analyze different elements involved in color correction for images taken from a system of cameras.
BibTeX:
@inbook{ThomasBook2013c,
  author = {Nozick, Vincent and Thomas, Jean-Baptiste},
  title = {Camera Calibration: Geometric and Colorimetric Correction},
  booktitle = {3D Video},
  publisher = {John Wiley & Sons, Inc.},
  year = {2013},
  pages = {91--112},
  url = {http://dx.doi.org/10.1002/9781118761915.ch5},
  doi = {10.1002/9781118761915.ch5}
}
Thomas J-B (2009), "Colorimetric characterization of displays and multi-display systems" PhD.
BibTeX:
@incollection{Thomasthesis2009,
  author = {Thomas, Jean-Baptiste},
  editor = {Université de Bourgogne},
  title = {Colorimetric characterization of displays and multi-display systems},
  publisher = {PhD},
  year = {2009},
  url = {http://jbthomas.org/Thesis/thesis-2009.pdf}
}
Created by JabRef on 27/01/2017.

TECHNICAL REPORTS, MISCELLANEOUS:

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Thomas J-B (2009), "Colorimetric characterization of displays and multi-display systems", November, 2009.
BibTeX:
@incollection{ThomasTalk2009,
  author = {Thomas, Jean-Baptiste},
  editor = {Invited Talk VISOR Seminar},
  title = {Colorimetric characterization of displays and multi-display systems},
  year = {2009},
  url = {http://jbthomas.org/TechReport/seminarVISOR2009.pdf}
}
Thomas J-B (2014), "Sensors based on MultiSpectral Filter Arrays", March, 2014.
BibTeX:
@incollection{ThomasTalk2014a,
  author = {Thomas, Jean-Baptiste},
  editor = {Invited Talk ORA},
  title = {Sensors based on MultiSpectral Filter Arrays},
  year = {2014},
  url = {http://www.pole-ora.com/pages/projets/OPage_JTIMAGEPROC2014.php}
}
Thomas J-B (2014), "Filter array-based spectral imaging: Design choices and practical realization", September, 2014.
BibTeX:
@incollection{ThomasTalk2014b,
  author = {Thomas, Jean-Baptiste},
  editor = {Workshop of the hypercept project #5, Multispectral image capture, processing, and quality},
  title = {Filter array-based spectral imaging: Design choices and practical realization},
  year = {2014}
}
Thomas J-B (2014), "MultiSpectral Filter Arrays: Design and demosaicing", November - December, 2014.
BibTeX:
@incollection{ThomasTalk2014c,
  author = {Thomas, Jean-Baptiste},
  editor = {Guest lecture, LPNC, Grenoble and LISTIC, Annecy},
  title = {MultiSpectral Filter Arrays: Design and demosaicing},
  year = {2014}
}
Thomas J-B (2016), "MultiSpectral Filter Arrays: Tutorial and prototype definition", November - December, 2016.
BibTeX:
@incollection{ThomasTalk2016d,
  author = {Thomas, Jean-Baptiste},
  editor = {EPFL, Lausanne, NTNU-Gjovik},
  title = {MultiSpectral Filter Arrays: Tutorial and prototype definition},
  year = {2016}
}
Thomas J-B, Hardeberg J and Trémeau A (2012), "Draft Report on Cross-Media Color Reproduction and Display Characterization".
BibTeX:
@misc{ThomasTechReport2010,
  author = {Thomas, Jean-Baptiste and Hardeberg, JonY. and Trémeau, Alain},
  title = {Draft Report on Cross-Media Color Reproduction and Display Characterization},
  year = {2012},
  url = {http://jbthomas.org/TechReport/displaysCrossMedia2010.pdf}
}
Thomas J-B (2012), "Calibration de caméras couleurs. Rapport technique et références".
BibTeX:
@misc{ThomasTechReport2012,
  author = {Thomas, Jean-Baptiste},
  title = {Calibration de caméras couleurs. Rapport technique et références},
  year = {2012},
  url = {http://jbthomas.org/TechReport/cameraCalibration2012.pdf}
}
Created by JabRef on 31/01/2017.

PhDs CONDUCTED UNDER MY CO-SUPERVISION:

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ElKhoury J (2016), "Model and quality assessment of single image dehazing" PhD.
Abstract: This thesis is mainly related to color imaging science, involving many disciplines, such as color image enhancement, image formation, color reproduction, optical physics, radiometry, colorimetry,
image quality and psychophysics.
Dehazing aims at recovering the image information degraded by light scattering, e.g. bad weather.
This process is an ill-posed and a challenging problem. Although a variety of approaches have been
proposed, there is still room for further improvement and standardization. In this work, we investigate
the limitations of haze model in terms of accuracy of color image recovery. We address also the
link between the visibility deterioration and the spectral content of the images. Moreover, with the
multiple existing dehazing algorithms, it is mandatory to evaluate and compare their performance.
Indeed, only limited investigations have been performed on the quality of dehazing in particular on
the fidelity of the recovered material. Thus, we propose to evaluate the quality of dehazed images. To
this aim, a color and a multispectral hazy image databases have been conceived. These databases
represent with their ground truth clear image, an adequate tool to deal with dehazing quality in terms
of objective and subjective assessment.
BibTeX:
@incollection{ElKhourythesis2016,
  author = {ElKhoury, Jessica},
  editor = {Université de Bourgogne},
  title = {Model and quality assessment of single image dehazing},
  publisher = {PhD},
  year = {2016},
  url = {http://jbthomas.org/SupervisedPhD/2016JessicaElKhouryThesis.pdf}
}
Wang X (2016), "Filter array based spectral imaging : Demosaicking and design considerations" PhD, Doctoral thesis at NTNU;2016:251.
Abstract: Spectral imaging apparatus in current use are often cumbersome, costly and slow in operation, which becomes a major obstacle to extensive use of spectral imaging in several application areas. In recent years, the technical and commercial success of color filter array (CFA) based imaging systems has motivated researchers to generalise and expand the concept of CFA to achieve efficient spectral imaging through the use of the spectral filter array (SFA). This dissertation expounds the research into the filter array approach to spectral imaging based on a simulation framework, from the development of demosaicking methods to the design and evaluation at the system level. The dissertation first presents the development of the field of spectral imaging from its roots in spectroscopy and imaging, and explores the state-of-the-art solutions based on SFA from design to realisation. It then proposes a simulation framework composed of the major parts in a typical imaging pipeline. Based on this, the influence of chromatic aberration on CFA demosaicking and the impact of filter bandwidth on spectral reconstruction were evaluated. The results helped to better understand the delicate interactions between the components in the pipeline and verify the validity of the simulation framework. On the basis of the framework, three novel SFA demosaicking methods were developed and evaluated. The methods differ fundamentally and thus featuring distinct properties, as confirmed by the experimental results. The key to understanding the differences lies in the way demosaicking methods deal with the spatial and spectral correlation between pixels in a mosaicked image. An evaluation of the colorimetric performance shows that a properly designed SFA-based imaging system may also be useful for colour image acquisition. Lastly, performance of the proposed and conventional demosaicking methods were scrutinised, given the characteristics and parameters of a real-world SFA sensor design. We conclude that, for a successful SFA-based spectral imaging system design, it is important to consider carefully the joint influence of all the involved modules as well as the requirements and constraints of applications. And we hope that the use of SFA based spectral imaging is expected to be wider in the foreseeable future in the light of technological advances and market demand.
BibTeX:
@incollection{Wangthesis2016,
  author = {Wang, Xingbo},
  editor = {NTNU},
  title = {Filter array based spectral imaging : Demosaicking and design considerations},
  publisher = {PhD, Doctoral thesis at NTNU;2016:251},
  year = {2016},
  url = {http://jbthomas.org/SupervisedPhD/2016XingboWangThesis.pdf}
}
Zhao P (2015), "Colorimetric characterization of displays and multi-display systems" PhD, Doctoral Dissertations at Gjovik University College;3-2015.
Abstract: This thesis presents the outcomes of research carried out by the PhD candidate Ping Zhao during 2012 to 2015 in Gjøvik University College. The underlying research was a part of the HyPerCept project, in the program of Strategic Projects for University Colleges, which was funded by The Research Council of Norway. The research was engaged under the supervision of Professor Jon Yngve Hardeberg and co-supervision of Associate Professor Marius Pedersen, from The Norwegian Colour and Visual Computing Laboratory, in the Faculty of Computer Science and Media Technology of Gjøvik University College; as well as the co-supervision of Associate Professor Jean-Baptiste Thomas, from The Laboratoire Electronique, Informatique et Image, in the Faculty of Computer Science of Universit´e de Bourgogne. The main goal of this research was to develop a fast and an inexpensive camera based display image quality assessment framework. Due to the limited time frame, we decided to focus only on projection displays with static images displayed on them. However, the proposed methods were not limited to projection displays, and they were expected to work with other types of displays, such as desktop monitors, laptop screens, smart phone screens, etc., with limited modifications. The primary contributions from this research can be summarized as follows:
1. We proposed a camera based display image quality assessment framework, which was originally designed for projection displays but it can be used for other types of displays with limited modifications.
2. We proposed a method to calibrate the camera in order to eliminate unwanted vignetting artifact, which is mainly introduced by the camera lens.
3. We proposed a method to optimize the camera’s exposure with respect to the measured luminance of incident light, so that after the calibration all camera sensors share a common linear response region.
4. We proposed a marker-less and view-independent method to register one captured image with its original at a sub-pixel level, so that we can incorporate existing full reference image quality metrics without modifying them.
5. We identified spatial uniformity, contrast and sharpness as the most important image quality attributes for projection displays, and we used the proposed framework to evaluate the prediction performance of the state-of-the-art image quality metrics regarding these attributes.
The proposed image quality assessment framework is the core contribution of this research. Comparing to conventional image quality assessment approaches, which were largely based on the measurements of colorimeter or spectroradiometer, using camera as the acquisition device has the advantages of quickly recording all displayed pixels in one shot, relatively inexpensive to purchase the instrument. Therefore, the consumption of time and resources for image quality assessment can be largely reduced. We proposed a method to calibrate the camera in order to eliminate unwanted vignetting artifact primarily introduced by the camera lens. We used a hazy sky as a closely uniform light source, and the vignetting mask was generated with respect to the median sensor responses over i only a few rotated shots of the same spot on the sky. We also proposed a method to quickly determine whether all camera sensors were sharing a common linear response region. In order to incorporate existing full reference image quality metrics without modifying them, an accurate registration of pairs of pixels between one captured image and its original is required. We proposed a marker-less and view-independent image registration method to solve this problem. The experimental results proved that the proposed method worked well in the viewing conditions with a low ambient light. We further identified spatial uniformity, contrast and sharpness as the most important image quality attributes for projection displays. Subsequently, we used the developed framework to objectively evaluate the prediction performance of the state-of-art image quality metrics regarding these attributes in a robust manner. In this process, the metrics were benchmarked with respect to the correlations between the prediction results and the perceptual ratings collected from subjective experiments. The analysis of the experimental results indicated that our proposed methods were effective and efficient. Subjective experiment is an essential component for image quality assessment; however it can be time and resource consuming, especially in the cases that additional image distortion levels are required to extend the existing subjective experimental results. For this reason, we investigated the possibility of extending subjective experiments with baseline adjustment method, and we found that the method could work well if appropriate strategies were applied. The underlying strategies referred to the best distortion levels to be included in the baseline, as well as the number of them.
BibTeX:
@incollection{Zhaothesis2015,
  author = {Zhao, Ping},
  editor = {NTNU},
  title = {Colorimetric characterization of displays and multi-display systems},
  publisher = {PhD, Doctoral Dissertations at Gjovik University College;3-2015},
  year = {2015},
  url = {http://jbthomas.org/SupervisedPhD/2015PingZhaoThesis.pdf}
}
Created by JabRef on 05/04/2017.