This book constitutes thoroughly revised and selected papers from the 13th International Joint Conference on Computer Vision, Imaging and Computer Graphics Theory and Applications, VISIGRAPP 2018, held in Funchal-Madeira, Portugal, in January 2018. The 18 thoroughly revised and extended papers presented in this volume were carefully reviewed and selected from 317 submissions. The papers contribute to the understanding of relevant trends of current research on computer graphics; human computer interaction; information visualization; computer vision.

This introduction to wavelets provides computer graphics professionals and researchers with the mathematical foundations for understanding and applying this powerful tool.

In the arts and sciences, as well as in our daily lives, symmetry has made a profound and lasting impact. Likewise, a computational treatment of symmetry and group theory (the ultimate mathematical formalization of symmetry) has the potential to play an important role in computational sciences. Though the term Computational Symmetry was formally defined a decade ago by the first author, referring to algorithmic treatment of symmetries, seeking symmetry from digital data has been attempted for over four decades. Computational symmetry on real world data turns out to be challenging enough that, after decades of effort, a fully automated symmetry-savvy system remains elusive for real world applications. The recent resurging interests in computational symmetry for computer vision and computer graphics applications have shown promising results. Recognizing the fundamental relevance and potential power that computational symmetry affords, we offer this survey to the computer vision and computer graphics communities. This survey provides a succinct summary of the relevant mathematical theory, a historic perspective of some important symmetry-related ideas, a partial yet timely report on the state of the arts symmetry detection algorithms along with its first quantitative benchmark, a diverse set of real world applications, suggestions for future directions and a comprehensive reference list.

Many approaches have been proposed to solve the problem of finding the optic flow field of an image sequence. Three major classes of optic flow computation techniques can discriminated (see for a good overview Beauchemin and Barron IBeauchemin19951): gradient based (or differential) methods; phase based (or frequency domain) methods; correlation based (or area) methods; feature point (or sparse data) tracking methods; In this chapter we compute the optic flow as a dense optic flow field with a multi scale differential method. The method, originally proposed by Florack and Nielsen [Florack1998a] is known as the Multiscale Optic Flow Constrain Equation (MOFCE). This is a scale space version of the well known computer vision implementation of the optic flow constraint equation, as originally proposed by Horn and Schunck [Horn1981]. This scale space variation, as usual, consists of the introduction of the aperture of the observation in the process. The application to stereo has been described by Maas et al. [Maas 1995a, Maas 1996a]. Of course, difficulties arise when structure emerges or disappears, such as with occlusion, cloud formation etc. Then knowledge is needed about the processes and objects involved. In this chapter we focus on the scale space approach to the local measurement of optic flow, as we may expect the visual front end to do. 17. 2 Motion detection with pairs of receptive fields As a biologically motivated start, we begin with discussing some neurophysiological findings in the visual system with respect to motion detection.

INSTICC organized the third edition of VISIGRAPP that took place in Funchal- Madeira, Portugal in January 2008 after successful previous editions. This book - cludes selected papers from VISIGRAPP 2008, the Joint Conference on Computer Vision Theory and Applications (VISAPP) and Computer Graphics Theory and - plications (GRAPP). The conference was intended to stimulate the exchange of ideas on the topics of c- puter vision and computer graphics. We received a high number of paper submissions: 374 in total for both conferences. We had contributions from more than 50 countries in all continents. This confirms the success and global dimension of these jointly organized conferences. After a rigorous double-blind evaluation method, 78 submissions were accepted as full papers. From those, 20 were selected for this book. To ensure the sci- tific quality of the contributions, these were selected from the ones that were evaluated with the highest scores by the VISIGRAPP Program Committee Members and then they were extended and revised by the authors. Special thanks go to all contributors and re- rees, without whom this book would not have been possible. VISIGRAPP 2008 also featured the comments of keynote speakers, in alphabetical order, Adrian Hilton (University of Surrey, UK), Geneviève Lucet (Computer S- vices for Research at the UNAM, Mexico), Peter Sturm (INRIA Rhône-Alpes, France) and Sharathchandra Pankanti (IBM - Exploratory Computer Vision Group, USA), who are internationally recognized researchers. The presentations represented an - portant contribution to the overall quality of the conference.

This book includes selected papers from VISIGRAPP 2007, the Joint Conference on Computer Vision and Computer Graphics, comprising two component conferences, namely, the International Conference on Computer Vision Theory and Applications (VISAPP) and the International Conference on Computer Graphics Theory and App- cations (GRAPP), held in Barcelona, Spain, during March 8–11, 2007. We received quite a high number of paper submissions: 382 in total for both conf- ences. We had contributions from more than 50 countries in all five continents. This confirms the success and global dimension of these jointly organized conferences. After a rigorous double-blind evaluation method, a total of 78 submissions were accepted as full papers. From those, 18 got selected for inclusion in this book. To ensure the sci- tific quality of the contributions, these were selected from papers that were evaluated with the highest scores by the VISIGRAPP Program Committee members and then they were extended and revised by the authors. Special thanks go to all contributors and re- rees, without whom this book would not have been possible. VISIGRAPP 2007 included four invited keynote lectures, presented by internati- ally recognized researchers. The presentations represented an important contribution to increasing the overall quality of the conference. We would like to express our - preciation to all invited keynote speakers, in alphabetical order: Jake K. Aggarwal (The University of Texas at Austin/USA), André Gagalowicz (INRIA/France), Wo- gang Heidrich (University of British Columbia/Canada), Mel Slater (Universitat Politècnica de Catalunya/Spain).

The focus of this book is on providing a thorough treatment of image processing with an emphasis on those aspects most used in computer graphics. Throughout, the authors concentrate on describing and analysing the underlying concepts rather than on presenting algorithms or pseudocode. As befits a modern introduction to this topic, a healthy balance is struck between discussing the underlying mathematics of the subject and the main topics covered: signal processing, data discretization, the theory of colour and different colour systems, operations in images, dithering and half-toning, warping and morphing, and image processing.