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- Unveiling the hand of a 19th century artist with binary image classification and bag-of-featuresPublication . Montagner, Cristina; Jesus, Rui; Correia, Nuno; Melo, Maria J.; Villarigues, Marcia; Macedo, Rita; Freitas, Helena deThe shape, orientation and distribution of brushstrokes are distinctive markers left by the artist on the surface of a painting. Consequently, they are useful as additional evidence to decide on issues of attribution and authenticity. This paper proposes an image classification algorithm for the paintings of Amadeo de Souza-Cardoso, a modern Portuguese artist who is at the top of the Portuguese police’s list of forged artists. The proposed system is based on a binary classification using bag-of-features (SIFT descriptors and a Gabor filter) for image representation. Experimental results using the algorithm show that the classification of the paintings by extracting brushstroke information is very promising.
- Methods for automatic and assisted image annotationPublication . Jesus, Rui; Abrantes, Arnaldo; Correia, NunoPersonal memories composed of digital pictures are very popular at the moment. To retrieve these media items annotation is required. During the last years, several approaches have been proposed in order to overcome the image annotation problem. This paper presents our proposals to address this problem. Automatic and semi-automatic learning methods for semantic concepts are presented. The automatic method is based on semantic concepts estimated using visual content, context metadata and audio information. The semi-automatic method is based on results provided by a computer game. The paper describes our proposals and presents their evaluations.
- Features combination for art authentication studies: brushstroke and materials analysis of Amadeo de Souza-CardosoPublication . Montagner, Cristina; Jesus, Rui; Correia, Nuno; Vilarigues, Márcia; Macedo, Rita; Melo, Maria JoãoThis work presents a tool to support authentication studies of paintings attributed to the modernist Portuguese artist Amadeo de Souza-Cardoso (1887-1918). The strategy adopted was to quantify and combine the information extracted from the analysis of the brushstroke with information on the pigments present in the paintings. The brushstroke analysis was performed combining Gabor filter and Scale Invariant Feature Transform. Hyperspectral imaging and elemental analysis were used to compare the materials in the painting with those present in a database of oil paint tubes used by the artist. The outputs of the tool are a quantitative indicator for authenticity, and a mapping image that indicates the areas where materials not coherent with Amadeo's palette were detected, if any. This output is a simple and effective way of assessing the results of the system. The method was tested in twelve paintings obtaining promising results.
- An interface to retrieve personal memories using an iconic visual languagePublication . Jesus, Rui; Romão, Teresa; Correia, NunoRelevant past events can be remembered when visualizing related pictures. The main difficulty is how to find these photos in a large personal collection. Query definition and image annotation are key issues to overcome this problem. The former is relevant due to the diversity of the clues provided by our memory when recovering a past moment and the later because images need to be annotated with information regarding those clues to be retrieved. Consequently, tools to recover past memories should deal carefully with these two tasks. This paper describes a user interface designed to explore pictures from personal memories. Users can query the media collection in several ways and for this reason an iconic visual language to define queries is proposed. Automatic and semi-automatic annotation is also performed using the image content and the audio information obtained when users show their images to others. The paper also presents the user interface evaluation based on tests with 58 participants.
- ARZombie: A mobile augmented reality game with multimodal interactionPublication . Cordeiro, Diogo; Correia, Nuno; Jesus, RuiAugmented reality games have the power to extend virtual gaming into real world scenarios with real people, while enhancing the senses of the user. This paper describes the ARZombie game developed with the aim of studying and developing mobile augmented reality applications, specifically for tablets, using face recognition interaction techniques. The goal of the ARZombie player is to kill zombies that are detected through the display of the device. Instead of using markers as a mean of tracking the zombies, this game incorporates a facial recognition system, which will enhance the user experience by improving the interaction of players with the real world. As the player moves around the environment, the game will display virtual zombies on the screen if the detected faces are recognized as belonging to the class of the zombies. ARZombie was tested with users to evaluate the interaction proposals and its components were evaluated regarding the performance in order to ensure a better gaming experience.