4 research outputs found

    Blur Invariants for Image Recognition

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    Blur is an image degradation that is difficult to remove. Invariants with respect to blur offer an alternative way of a~description and recognition of blurred images without any deblurring. In this paper, we present an original unified theory of blur invariants. Unlike all previous attempts, the new theory does not require any prior knowledge of the blur type. The invariants are constructed in the Fourier domain by means of orthogonal projection operators and moment expansion is used for efficient and stable computation. It is shown that all blur invariants published earlier are just particular cases of this approach. Experimental comparison to concurrent approaches shows the advantages of the proposed theory.Comment: 15 page

    Métrica de evaluación de simetría global en imágenes naturales basadas en valoraciones de observadores humanos

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    En este proyecto se estudia la correlación entre la simetría global existente en imágenes naturales con la percepción humana de las mismas mediante la creación de una métrica continua capaz de evaluar la simetría en estas imágenes. Este trabajo se divide en dos partes: una primera parte en la que se realiza un experimento para extraer valoraciones humanas respecto a la cantidad de simetría de una imagen, se extraen características de las imágenes y se crean diversos algoritmos para poder relacionar estas características con las valoraciones humanas; y una segunda parte en la que se realiza un estudio del experimento y se mejoran los algoritmos basándose en este estudio. Adicionalmente, se estudian diversas métricas ya existentes que permiten darle una valoración de cuán simétrica es a una imagen y se utilizan como modelos para poder realizar una comparación de los resultados obtenidos.This project studies the correlation between the global symmetry that exists in natural images with the human perception of them by creating a continuous metric capable of evaluating the existing symmetry in these images. This work is divided into two parts: a first part in which an experiment is carried out to extract human evaluations regarding the amount of symmetry of an image, characteristics of the images are extracted and algorithms are created to be able to relate these characteristics with the human evaluations; and a second part in which a study of the experiment is carried out and the algorithms are improved based on this study. Additionally, various existing metrics are studied that allow an assessment of how symmetric an image is and are used as models to be able to make a comparison of the results obtained.En aquest projecte s'estudia la correlació entre la simetria global existent en imatges naturals amb la percepció humana de les mateixes mitjançant la creació d'una mètrica contínua capaç d'avaluar la simetria en aquestes imatges. Aquest treball es divideix en dues parts: una primera part en la qual es realitza un experiment per a extreure valoracions humanes respecte a la quantitat de simetria d'una imatge, s'extreuen característiques de les imatges i es creen diversos algorismes per a poder relacionar aquestes característiques amb les valoracions humanes; i una segona part en la qual es realitza un estudi de l'experiment i es milloren els algorismes basant-se en aquest estudi. Addicionalment, s'estudien diverses mètriques ja existents que permeten donar-li una valoració de que simètrica és a una imatge i s'utilitzen com a models per a poder realitzar una comparació dels resultats obtinguts

    Recognition of Symmetric 3D Bodies

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    The paper deals with the recognition of symmetric three-dimensional (3D) bodies that can be rotated and translated. We provide a complete list of all existing combinations of rotation and reflection symmetries in 3D. We define 3D complex moments by means of spherical harmonics, and the influence of individual symmetry groups on complex moment values is studied. Each particular symmetry pre-defines certain moment values. These moments can no longer differentiate between two objects of the same symmetry, which decreases the recognition power of the feature set. They should not be included when constructing the invariants. Translation and rotation invariants up to the fourth order are presented and their performance is studied on both artificial and real data
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