30 years of demosaicing

This paper proposes a review of thirty years of the development of demosaicing algorithms used in digital camera for the reconstruction of color image. Most recent digital camera used a single sensor in front of a color filter array is placed. This sensor sample a single chromatic value per spatial position and an interpolation algorithm is needed for the definition of a color image with three components per spatial position. This article shows that the whole signal and image processing technics have been used for solving this problem. Moreover, a new method proposed recently by the author and collaborators is decribed. This method based on a model of chromatic sampling by the cones in the retina highlights the nature of spatio-chromatic sampling in digital camera with single sensor.Cet article propose une revue de trente années de développement des algorithmes de démosaïçage utilisés dans les caméras numériques pour la reconstruction des images couleurs. La plupart des caméras numériques actuelles utilisent un seul capteur devant lequel est placée une matrice de filtres couleurs. Ce capteur échantillonne par conséquent une seule couleur par position spatiale et un algorithme d'interpolation est nécessaire pour la définition d'une image couleur avec trois composantes par position spatiale. Cet article montre que l'ensemble des techniques du traitement du signal et des images a été utilisé pour résoudre ce problème. Aussi, une nouvelle méthode proposée récemment par l'auteur et collaborateurs est décrite. Cette méthode, basée sur un modèle d'échantillonnage couleur par les cônes de la rétine, révèle la nature de l'échantillonnage spatio-chromatique dans les caméras couleur à un seul capteur

Biomimetic Space-Variant Sampling in a Vision Prosthesis Improves the User's Skill in a Localization Task

In this experiment, we test the hypothesis of whether a 'retina-like' space variant sampling pattern can improve the efficiency of a visual prosthesis. Subjects wearing a visuo-auditory substitution system were tested for their ability to point at visual targets. The test group (space-variant sampling), performed significantly better than the control group (uniform sampling). The pointing accuracy was enhanced, as was the speed to find the target. Surprisingly, the time spanned to complete the training was also reduced, suggesting that this space-variant sampling scheme facilitates the mastering of sensorimotor contingencies

Capteurs CMOS à Photosites standard

Brevet N°CNRS N°WO 2014/19562

Joint demosaicing and super-resolution imaging from a set of unregistered aliased images

We present a new algorithm that performs demosaicing and super-resolution jointly from a set of raw images sampled with a color filter array. Such a combined approach allows us to compute the alignment parameters between the images on the raw camera data before interpolation artifacts are introduced. After image registration, a high resolution color image is reconstructed at once using the full set of images. For this, we use normalized convolution, an image interpolation method from a nonuniform set of samples. Our algorithm is tested and compared to other approaches in simulations and practical experiments. © 2007 SPIE-IS&T.status: publishe

The importance of low spatial frequency information for recognizing fearful facial expressions.

International audienc

Real-time bio-inspired retina simulation software.

The way the retina processes and format visual information contributes, to a large extent, to the efficiency, compaction and reliability of the human visual system, which is of strong interest to artificial vision systems. Based on the transfer function of retinal neurons and their synaptic interaction, our application software computes, in real time, the different outputs of the human retina, from photoreceptors to Magno and Parvo ganglion cells. It is modular and fully configurable so that it can be used in a wide field of applications. A video camera is available to experiment, in live, how the different outputs of the retina reacts to various visual stimulations, and a user interface gives the oportunity to test the effects of retina space and time parameters as well as intensity and contrast local adaptation gain control. Attendees can also bring their own video data to be processed