Fusion of MultiSpectral and Panchromatic Images Based on Morphological Operators

International audienceNonlinear decomposition schemes constitute an alternative to classical approaches for facing the problem of data fusion. In this paper we discuss the application of this methodology to a popular remote sensing application called pansharpening, which consists in the fusion of a low resolution multispectral image and a high resolution panchromatic image. We design a complete pansharpening scheme based on the use of morphological half gradients operators and demonstrate the suitability of this algorithm through the comparison with state of the art approaches. Four datasets acquired by the Pleiades, Worldview-2, Ikonos and Geoeye-1 satellites are employed for the performance assessment, testifying the effectiveness of the proposed approach in producing top-class images with a setting independent of the specific sensor

Colour morphology and its approaches

Mathematical morphology was first applied to binary images and readily extended to grey-level images. In extending mathematical morphology to colour it is difficult to define a suitable unambiguous ordering. We present two complete ordering schemes based on colour difference and similarity ordering for colour morphology. A novel colour difference formula is first introduced. This colour difference formula is based on colour extrema derived from a simple physical model of image formation and avoids the more arbitrary mathematical and perceptual definitions previously reported. Moreover, we define similarity criteria as the basis for mathematical morphology that can be used with flat and non-flat structuring elements. The proposed orderings meet the properties of mathematical morphology, and provide a harmonised approach for binary, grey-level and colour morphology. A comparison of ordering schemes for dilation, erosion, opening, closing and filtering operator shows the colour difference-based ordering presented here to be at least as good as other ordering schemes and better than some of the well principled, previously reported methods in not generating artefacts and reducing image noise. Additionally, the development of a similarity-based ordering to perform morphological gradient and Hit-or-Miss transforms for colour images is presented

Contributions en morphologie mathématique pour l'analyse d'images multivariées

This thesis contributes to the field of mathematical morphology and illustrates how multivariate statistics and machine learning techniques can be exploited to design vector ordering and to include results of morphological operators in the pipeline of multivariate image analysis. In particular, we make use of supervised learning, random projections, tensor representations and conditional transformations to design new kinds of multivariate ordering, and morphological filters for color and multi/hyperspectral images. Our key contributions include the following points:• Exploration and analysis of supervised ordering based on kernel methods.• Proposition of an unsupervised ordering based on statistical depth function computed by random projections. We begin by exploring the properties that an image requires to ensure that the ordering and the associated morphological operators can be interpreted in a similar way than in the case of grey scale images. This will lead us to the notion of background/foreground decomposition. Additionally, invariance properties are analyzed and theoretical convergence is showed.• Analysis of supervised ordering in morphological template matching problems, which corresponds to the extension of hit-or-miss operator to multivariate image by using supervised ordering.• Discussion of various strategies for morphological image decomposition, specifically, the additive morphological decomposition is introduced as an alternative for the analysis of remote sensing multivariate images, in particular for the task of dimensionality reduction and supervised classification of hyperspectral remote sensing images.• Proposition of an unified framework based on morphological operators for contrast enhancement and salt- and-pepper denoising.• Introduces a new framework of multivariate Boolean models using a complete lattice formulation. This theoretical contribution is useful for characterizing and simulation of multivariate textures.Cette thèse contribue au domaine de la morphologie mathématique et illustre comment la statistique multivariée et les techniques d'apprentissage numérique peuvent être exploitées pour concevoir un ordre dans l'espace des vecteurs et pour inclure les résultats d'opérateurs morphologiques au processus d'analyse d'images multivariées. En particulier, nous utilisons l'apprentissage supervisé, les projections aléatoires, les représentations tensorielles et les transformations conditionnelles pour concevoir de nouveaux types d'ordres multivariés et de nouveaux filtres morphologiques pour les images multi/hyperspectrales. Nos contributions clés incluent les points suivants :• Exploration et analyse d'ordre supervisé, basé sur les méthodes à noyaux.• Proposition d'un ordre nonsupervisé, basé sur la fonction de profondeur statistique calculée par projections aléatoires. Nous commençons par explorer les propriétés nécessaires à une image pour assurer que l'ordre ainsi que les opérateurs morphologiques associés, puissent être interprétés de manière similaire au cas d'images en niveaux de gris. Cela nous amènera à la notion de décomposition en arrière plan. De plus, les propriétés d'invariance sont analysées et la convergence théorique est démontrée.• Analyse de l'ordre supervisé dans les problèmes de correspondance morphologique de patrons, qui correspond à l'extension de l'opérateur tout-ou-rien aux images multivariées grâce à l‘utilisation de l'ordre supervisé.• Discussion sur différentes stratégies pour la décomposition morphologique d'images. Notamment, la décomposition morphologique additive est introduite comme alternative pour l'analyse d'images de télédétection, en particulier pour les tâches de réduction de dimension et de classification supervisée d'images hyperspectrales de télédétection.• Proposition d'un cadre unifié basé sur des opérateurs morphologiques, pour l'amélioration de contraste et pour le filtrage du bruit poivre-et-sel.• Introduction d'un nouveau cadre de modèles Booléens multivariés en utilisant une formulation en treillis complets. Cette contribution théorique est utile pour la caractérisation et la simulation de textures multivariées

Automatic classification of skin lesions using color mathematical morphology-based texture descriptors

SPIE : Society of Photo-Optical Instrumentation EngineersInternational audienceIn this paper an automatic classification method of skin lesions from dermoscopic images is proposed. This method is based on color texture analysis based both on color mathematical morphology and Kohonen Self-Organizing Maps (SOM), and it does not need any previous segmentation process. More concretely, mathematical morphology is used to compute a local descriptor for each pixel of the image, while the SOM is used to cluster them and, thus, create the texture descriptor of the global image. Two approaches are proposed, depending on whether the pixel descriptor is computed using classical (i.e. spatially invariant) or adaptive (i.e. spatially variant) mathematical morphology by means of the Color Adaptive Neighborhoods (CANs) framework. Both approaches obtained similar areas under the ROC curve (AUC): 0.854 and 0.859 outperforming the AUC built upon dermatologists' predictions (0.792)

Mathematical Morphology on the Sphere: Application to Polarimetric Image processing

Projecte final de carrera fet en col.laboració amb Centre de morphologie mathématique, École des Mines de ParisEnglish: The fully polarimetric synthetic aperture radar (PolSAR) provides data containing the complete scattering information. Therefore, these data have drawn more attention in recent years. PolSAR data can be represented as polarization states on a sphere. We present image processing techniques based on the analysis of the polarimetric information within its location on the sphere. Mathematical morphology is a well-known nonlinear approach for image processing. It is based on the computation of minimum and maximum values of local neighborhoods. That necessitates the existence of an ordering relationship between the points to be treated. The lack of a natural ordering on the sphere presents an inherent problem when defining morphological operators extended to unit sphere. We analyze in this project some proposals to the problem of ordering on the unit sphere, leading to formulations of morphological operators suited to the configuration of the data. The notion of local supremum and infimum is introduced, which allows to define the dilation and erosion on the sphere. Supervised orderings are considered and its associated operators for target recognition issues. We also present various filtering procedures for denoising purposes. The diferent methods studied in this project pursuit the generalization of the morphological operators on the sphere. Through the analysis performed, we pretend to achieve an understanding of the data and automation of the target detection.Castellano: El radar de apertura sintética totalmente polarimétrico (PolSAR) proporciona datos que contienen la información completa de dispersión. Estos datos han captado más atención en los últimos años. Los datos PolSAR pueden ser representados como estados de polarización en una esfera. Se presentan las técnicas de procesamiento de imágenes basadas en el análisis de la información polarimétrica y en su ubicación en la esfera. La morfología matemática es una técnica no lineal para el procesamiento de imágenes. Se basa en el cálculo de los valores mínimos y máximos alrededor de un punto. Precisa de la existencia de una relación de orden entre los puntos a tratar. La falta de un orden natural en la esfera presenta un problema inherente a la hora de definir los operadores morfológicos extendidos a la esfera unidad. En este proyecto se analizan algunas propuestas para el problema del orden en la esfera unidad, lo que da lugar a formulaciones de los operadores morfológicos adaptados a la configuración de los datos. Se introduce la noción de supremo e ínfimo local, lo que permite definir la dilatación y la erosión en la esfera. Consideramos órdenes supervisados y sus operadores asociados para problemas de reconocimiento de objetivos. También se presentan varios procedimientos de filtrado para la eliminación de ruido. Los diferentes métodos estudiados en este proyecto persiguen la generalización de los operadores morfológicos a la esfera. A través del análisis realizado, se pretende lograr una comprensión de los datos y la autCatalà: El radar d'obertura sintètica totalment polarimètric (PolSAR) proporciona dades que contenen la informació completa de dispersió. Aquestes dades han captat més atenció en els últims anys. Les dades PolSAR poden ser representades com a estats de polarizació en una esfera. Es presenten tècniques de processament d'imatge basades en l'anàlisi de la informació polarimètrica i en la seva ubicació en l'esfera. La morfologia matemàtica és una tècnica no lineal per al processament d'imatges. Es basa en el càlcul dels valors mínim i màxim al voltant d'un punt. Precisa de l'existència d'una relació d'ordre entre els punts a tractar. La manca d'un ordre natural en l'esfera presenta un problema inherent a l'hora de definir els operadors morfològics estesos a l'esfera unitat. En aquest projecte s'analitzen algunes propostes per al problema de l'ordre en l'esfera unitat, el que dóna lloc a formulacions dels operadors morfològics adaptats a la configuració de les dades. S'introdueix la noció de suprem i mínim local, el que permet definir la dilatació i l'erosió en l'esfera. Considerem ordres supervisats i els seus operadors associats per a problemes de reconeixement d'objectius. També es presenten diversos procediments de filtratge per a la eliminació de soroll. Els diferents mètodes estudiats en aquest projecte busquen la generalizació dels operadors morfològics a l'esfera. Mitjançcant l'anàlisi realitzat, es pretén aconseguir la comprensió de les dades i l'a

The Bitonic Filter: Linear Filtering in an Edge-preserving Morphological Framework.

A new filter is presented which has better edge and detail preserving properties than a median, noise reduction capability similar to a Gaussian, and is applicable to many signal and noise types. It is built on a definition of signal as bitonic, i.e. containing only one local maxima or minima within the filter range. This definition is based on data ranking rather than value, hence the bitonic filter comprises a combination of non-linear morphological and linear operators. It has no data-level-sensitive parameters and can locally adapt to the signal and noise levels in an image, precisely preserving both smooth and discontinuous signals of any level when there is no noise, but also reducing noise in other areas without creating additional artefactual noise. Both the basis and the performance of the filter are examined in detail, and it is shown to be a significant improvement on the Gaussian and median. It is also compared over various noisy images to the image-guided filter, anisotropic diffusion, non-local means, the grain filter, and self-dual forms of levelling and rank filters. In terms of signal-to-noise, the bitonic filter outperforms all these except non-local means, and sometimes anisotropic diffusion. However it gives good visual results in all circumstances, with characteristics which make it appropriate particularly for signals or images with varying noise, or features at varying levels. The bitonic has very few parameters, does not require optimisation nor prior knowledge of noise levels, does not have any problems with stability, and is reasonably fast to implement. Despite its non-linearity, it hence represents a very practical operation with general applicability

Heuristics for license plate localization and hardware implementation of Automatic License Plate Recognition (ALPR) system

The project “Heuristics for license plate localization and hardware implementation of Automatic License Plate Recognition (ALPR) system” deals with detection and recognition of license plate from a captured front view of any car. The work follows all the steps in an ALPR system like preprocessing, segmentation, and license plate identification, extraction of individual characters and finally recognition of each character to form a string to match with the registered License plate numbers. The main contribution in the work is to expedite the number plate isolation from a set of segmented candidates. It utilizes a set of heuristics typically transition from object to background and vice-versa, aspect ratio of the bounding boxes. This narrow down the number of candidates for further processing and further, we suggest a rank based identification of each character in the number plate. The process scheme along with the existing methodologies is integrated to develop the overall ALPR system. A set of standard images collected from internet as well as self-collected car images of staff vehicles are used for simulation. The experiments are conducted using OpenCV. For validation, a working ALPR hardware prototype is developed using AVR development board (ATmega32 microcontroller), GP2D120 distance measurement sensor (IR-sensor).Interfacing between PC and controller-board is done using serial port. The model works with an accuracy of 80%. The ALPR system has a further scope to improve the recognition speed using parallel processing of various sub-steps