Media item relighting technique
The present invention concerns a method of method of relighting a media item comprising media elements. The method comprises, for at least some of the media elements: determining, in a first signal domain, a light transport function describing the appearance of a particular media element under different illumination conditions at least partly defined by positions of a light source used to illuminate the particular media element; sampling, in the first signal domain, the light transport function of the particular media element to obtain discrete data samples of the light transport function; projecting the data samples in the first signal domain into a sampling grid to obtain spatially sparsely and non-uniformly sampled light transport function; interpolating, in a second signal domain, the sparsely and non-uniformly sampled light transport function to obtain an approximate light transport matrix in the second signal domain; converting the approximate light transport matrix into the first signal domain to obtain an approximate substantially uniformly sampled light transport function in the first signal domain; and using, in the first signal domain, the approximate substantially uniformly light transport function to relight the media item.
Selective Peptide-Mediated Enhanced Deposition of Polymer Fragrance Delivery Systems on Human Hair
ACS Applied Materials & Interfaces. 2017.
DOI : 10.1021/acsami.7b06569.
The deposition of fragrance delivery systems onto human hair from a shampoo formulation is a challenging task, as the primary function of shampoo is to cleanse the hair by removing primarily hydrophobic moieties. In this work, to tackle this challenge, phage-display-identified peptides that can bind to human hair under shampooing conditions are first identified and subsequently used to enhance the deposition of model fragrance delivery systems. These delivery systems are based on either poly(N-(2-hydroxypropyl)methacrylamide) (PHPMA) copolymers as a representative for polymeric profragrances or polyurethane/polyurea-type core-shell microcapsules as a model physical fragrance carrier. The incorporation of a hair-binding peptide enhanced the deposition of PHPMA copolymers by a factor of 3.5-5.0 depending on the extent of peptide incorporation, whereas 10 wt % surface functionalization of microcapsules with the peptide led to a 20-fold increase in their deposition. In a final experiment, treatment of the hair samples under realistic application conditions with the peptide-functionalized microcapsules resulted in an increase in fragrance release from the hair surfaces.
La Localisation du Jaune dans des Dessins de Dieux Réalisés par des Enfants
2017. Premiere annual conference of the international Alliance of Digital Humanities Organizations (DH 2017) , Montreal, Canada , August 8-11, 2017.
Handheld reflectance acquisition of paintings
IEEE Transactions on Computational Imaging. 2017.
DOI : 10.1109/TCI.2017.2749182.
Relightable photographs are alternatives to traditional photographs as they provide a richer viewing experience. However, the complex acquisition systems of existing techniques have restricted its usage to specialized setups. We introduce an easy-to-use and affordable solution for using smartphones to acquire the reflectance of paintings and similar almost-planar objects like tablets, engravings and textile. Our goal is to enable interactive relighting of such artifacts by everyone. In our approach, we non-uniformly sample the reflectance functions by moving the LED light of a smartphone and simultaneously tracking the position of the smartphone by using its camera. We then propose a compressive-sensing based approach for reconstructing the light transport matrix from the non-uniformly sampled data. As shown with experiments, we accurately reconstruct the light transport matrix that can then be used to create relightable photographs.
A Practical Method for Measuring the Spatial Frequency Response of Light Field Cameras
2014. IEEE International Conference on Image Processing , Paris, France , October 27-30, 2014. p. 5776-5780.
The spatial frequency response (SFR) is one of the most important and unbiased image quality measures of a digital camera. It evaluates to which extent a lens/sensor combination can resolve scene details. In this paper, we propose a simple and practical method to measure the SFR of microlens-based light field cameras. The particularity of such cameras resides in their ability to capture both spatial and angular information of the incoming light field thanks to an array of microlenses located in front of the sensor. Existing methods for measuring the SFR of conventional cameras are thus no longer applicable as the interaction between the main lens and the micro-lenses results in different resolving powers over the image plane that depend on the scene depths. By using a 3-dimensional target made of vertical lines printed on an inclined planar surface, we are able to measure the SFR across multiple depths in a single exposure. Our method allows SFR measurements from the raw light field itself as captured by the camera, and is thus independent of subsequent post-processing algorithms such as image reconstruction, digital refocusing or depth estimation. Our experimental results are consistent with theoretical bounds and reproducible.
Multispectral Interest Points for RGB-NIR Image Registration
2011. IEEE International Conference on Image Processing , Brussels, Belgium , September 2011.
DOI : 10.1109/ICIP.2011.6115818.
This paper explores the use of joint colour and near-infrared (NIR) information for feature based matching and image registration. In particular, we investigate multispectral generalisations of two popular interest point detectors (Harris and difference of Gaussians), and show that these give a marked improvement in performance when the extra NIR channel is available. We also look at the problem of multimodal RGB to NIR registration, and propose a variant of the SIFT descriptor that gives improved performance.