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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.
- Exploring the behavior of the player to change the course of a gamePublication . Beleza Sousa, João; Jesus, RuiThis paper proposes and discusses a horse racing game which explores the user behavior when playing, to change the gameplay. The game includes a module to capture and analyze, in real time, the body movement and the audio produced by the player. The paper describes the rational and design principles for the game and presents the main issues of the study conducted during the development of the game.
- 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.
- Mixing the game experience with the experience of meeting peoplePublication . Francisco, João; Jesus, RuiMeeting people face-to-face is a difficult task for many people. A mobile game can be the right "alibi" to help people to start a conversation. This paper describes the game "Knowing your Sympathy", which was developed with the purpose of knowing or making the first contact with people. The paper also presents the main questions of the study conducted during the evaluation of the game. The study was performed for 2 weeks by 13 participants living in the same or nearby neighborhoods.
- 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.
- Aplicação colaborativa em cenário real para animação de um cenário virtualPublication . Gomes, Telmo; Júnior, Carlos; Jesus, Rui; Jorge, PedroAs aplicações mais populares de mistura de cenários reais com cenários virtuais têm sido as aplicações de realidade aumentada e de realidade mista (realidade aumentada + virtualidade aumentada). Este trabalho mistura a realidade com ambientes virtuais numa aplicação colaborativa para duas pessoas. O projeto tem como objetivo o desenvolvimento de uma aplicação para navegação em ambientes virtuais através da interpretação de movimentos reais de uma pessoa. Estes movimentos são capturados por uma câmara, interpretados com algoritmos de processamento de vídeo e transmitidos para a interface de animação e lógica de jogo do Blender [1] (GameLogic [2]). Este artigo descreve a aplicação e apresenta resultados experimentais que ilustram o seu desempenho.
- Using deep learning techniques for authentication of Amadeo de Souza Cardoso paintings and drawingsPublication . Chen, Ailin; Jesus, Rui; Villarigues, MárciaThis paper investigates the application of a Convolutional Neural Network (CNN), AlexNet, on the authentication of paintings by different artists, including Portuguese painter Amadeo de Souza Cardoso, Chinese painter Daqian Zhang and Dutch painter Vincent van Gogh. The research is motivated by the studies on the identification of the works by Amadeo based on the painter’s brushstroke implementing Machine Learning algorithms combined with material analysis. The employment of CNN intends to improve the performance of the brushstroke analysis and increase the accuracy while authenticating an artist’ works. The results show that the implementation of AlexNet produces higher accuracies than its counterparts applying previous brushstroke analysis. Notably, when Amadeo drawings are included in the testing based on Amadeo paintings, the accuracies obtained with the original algorithm drop substantially, whilst the counterparts attained with AlexNet improved considerably. However, when other testing sets are introduced, especially the Chinese paintings, the accuracies show a great increase with the original algorithm but a significant decrease with AlexNet. It implies that AlexNet surpasses the traditional computation through learning by examples; it can potentially solve the problem of limited number of artworks by a specific artist for training.
- 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.