Reconstructing vectorised photographic images

We address the problem of representing captured images in the continuous mathematical space more usually associated with certain forms of drawn ('vector') images. Such an image is resolution-independent so can be used as a master for varying resolution-specific formats. We briefly describe the main features of a vectorising codec for photographic images, whose significance is that drawing programs can access images and image components as first-class vector objects. This paper focuses on the problem of rendering from the isochromic contour form of a vectorised image and demonstrates a new fill algorithm which could also be used in drawing generally. The fill method is described in terms of level set diffusion equations for clarity. Finally we show that image warping is both simplified and enhanced in this form and that we can demonstrate real histogram equalisation with genuinely rectangular histograms

Rendu expressif : communication visuelle et abstraction

communication oralecommunication oraleNational audienceno abstrac

Image abstraction painting of flow-like stylization

U radu se predstavlja tehnika ne-fotorealističkog prikaza u kojoj se iz fotografije dobiva stilizirana apstraktna slika s tonovima koji se prelijevaju. Zasnovana na Kuwahara filtrima i integralnim spiralnim linijama, naša metoda simultano apstrahira oblike i boje, zadržavajući u isto vrijeme osnovna obilježja slika. Posebno razvijamo metodu proširenja i detekcije ruba i usmjeravamo pažnju na specifična obilježja i rubne dijelove slike. Predloženi je algoritam promjenljiv i iterativan te se stupanj prelijevanja tonova i apstrakcije može regulirati. Eksperimentalni rezultati pokazuju da je učinkovitost naše metode u postizanju koherentne i stilizirane apstrakcije zadovoljavajuća, uz zadržavanje osnovnih obilježja iz zadanih fotografija.This paper presents a non-photorealistic rendering technique for producing flow-like abstraction stylization from a photograph. Based on anisotropic Kuwahara filtering in conjunction with line integral convolution, our method abstracts shapes and colors simultaneously while preserving features of images. In particular, we develop an edge detection and dilation method, to draw attention to salient features and image boundaries. This proposed algorithm is incremental and iterative, and therefore the degree of flow and abstraction can be controlled. Experimental results demonstrate that the effectiveness of our method in producing a coherent and flow-like abstraction stylization is satisfactory yet preserving features and directions from photographs

Importance-Driven Composition of Multiple Rendering Styles

International audienceWe introduce a non-uniform composition that integrates multiple rendering styles in a picture driven by an importance map. This map, either issued from saliency estimation or designed by a user, is introduced both in the creation of the multiple styles and in the final composition. Our approach accommodates a variety of stylization techniques, such as color desaturation, line drawing, blurring, edge-preserving smoothing and enhancement. We illustrate the versatility of the proposed approach and the variety of rendering styles on different applications such as images, videos, 3D scenes and even mixed reality. We also demonstrate that such an approach may help in directing user attention

Diffusion Curves: A Vector Representation for Smooth-Shaded Images

International audienceWe describe a new vector-based primitive for creating smooth-shaded images, called the diffusion curve. A diffusion curve partitions the space through which it is drawn, defining different colors on either side. These colors may vary smoothly along the curve. In addition, the sharpness of the color transition from one side of the curve to the other can be controlled. Given a set of diffusion curves, the final image is constructed by solving a Poisson equation whose constraints are specified by the set of gradients across all diffusion curves. Like all vector-based primitives, diffusion curves conveniently support a variety of operations, including geometry-based editing, keyframe animation, and ready stylization. Moreover, their representation is compact and inherently resolution-independent. We describe a GPU-based implementation for rendering images defined by a set of diffusion curves in realtime. We then demonstrate an interactive drawing system for allowing artists to create artworks using diffusion curves, either by drawing the curves in a freehand style, or by tracing existing imagery. The system is simple and intuitive: we show results created by artists after just a few minutes of instruction. Furthermore, we describe a completely automatic conversion process for taking an image and turning it into a set of diffusion curves that closely approximate the original image content

Artistic rendering enhancing global structure

Non-photorealistic rendering techniques usu- ally produce abstracted images. Most existing methods consider local rendering primitives, and global struc- tures may be easily obscured. Inspired by artists, we propose a novel image abstraction method that con- siders preserving or even enhancing global structures in the input images. Linear structures are particularly considered due to their wide existence and the avail- ability of techniques for their reliable detection. Based on various computer vision techniques, the algorithm is fully automatic. As demonstrated in the paper, artistic looking results are obtained for various types of images. The technique is orthogonal to many non-photorealistic rendering techniques and can be combined with them

Artistic minimal rendering with lines and blocks

Many non-photorealistic rendering techniques exist to produce artistic effects from given images. Inspired by various artists, interesting effects can be produced by using a minimal rendering, where the minimum refers to the number of tones as well as the number and complexity of the primitives used for rendering. Our method is based on various computer vision techniques, and uses a combination of refined lines and blocks (potentially simplified), as well as a small number of tones, to produce abstracted artistic rendering with sufficient elements from the original image. We also considered a variety of methods to produce different artistic styles, such as colour and 2-tone drawings, and use semantic information to improve renderings for faces. By changing some intuitive parameters a wide range of visually pleasing results can be produced. Our method is fully automatic. We demonstrate the effectiveness of our method with extensive experiments and a user study