NPAR12

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https://diglib.eg.org/handle/10.2312/991

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    Pixelated Image Abstraction
    (The Eurographics Association, 2012) Gerstner, Timothy; DeCarlo, Doug; Alexa, Marc; Finkelstein, Adam; Gingold, Yotam; Nealen, Andrew; Paul Asente and Cindy Grimm
    We present an automatic method that can be used to abstract high resolution images into very low resolution outputs with reduced color palettes in the style of pixel art. Our method simultaneously solves for a mapping of features and a reduced palette needed to construct the output image. The results are an approximation to the results generated by pixel artists. We compare our method against the results of a naive process common to image manipulation programs, as well as the hand-crafted work of pixel artists. Through a formal user study and interviews with expert pixel artists we show that our results offer an improvement over the naive methods.
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    Pixelating Vector Line Art
    (The Eurographics Association, 2012) Inglis, Tiffany C.; Kaplan, Craig S.; Paul Asente and Cindy Grimm
    Creating pixel art is a laborious process that requires artists to place individual pixels by hand. Although many image editors provide vector-to-raster conversions, the results produced do not meet the standards of pixel art: artifacts such as jaggies or broken lines frequently occur. We describe a novel Pixelation algorithm that rasterizes vector line art while adhering to established conventions used by pixel artists. We compare our results through a user study to those generated by Adobe Illustrator and Photoshop, as well as hand-drawn samples by both amateur and professional pixel artists.
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    Texture-Preserving Abstraction
    (The Eurographics Association, 2012) Mould, David; Paul Asente and Cindy Grimm
    Image abstraction traditionally eliminates texture, but doing so ignores the more elegant alternative of texture indication, e.g., suggesting the presence of texture through irregular silhouettes and locally chosen details. We propose a variant of geodesic image filtering which preserves the locally strongest edges, leading to preservation of both strong edges and weak edges depending on the surrounding context. Our contribution is to introduce cumulative range geodesic filtering, where the distance in the image plane is lengthened proportional to the color distance. We apply the new filtering scheme to abstraction applications and demonstrate that it has powerful structure-preserving capabilities, especially regarding preservation and indication of textures.
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    Shape-Free Hybrid Image
    (The Eurographics Association, 2012) Sripian, Peeraya; Yamaguchi, Yasushi; Paul Asente and Cindy Grimm
    Hybrid image is the image that changes interpretation according to viewing distance. By simply extracting the low and the high spatial frequency bands from two source images, the combination result image can be interpreted differently by viewing distance. This research finds the way to allow construction of hybrid image regardless of the source image's shape. Without the need to carefully pick the two images to be superimposed, hybrid image can be extended to use with any kind of image contents. There are two approaches for accomplishing shape-free hybrid image. Noise-inserted approach forces observers to perceive alternative low frequency image as meaningless noises in a close viewing distance, by manipulating contrast and details in the high frequency image. Color-inserted approach helps attract the visual attention for the high frequency image perception is also introduced in this research. Finally, hybrid image recognition experiment proves that our proposed method yield a better recognition rate over the original method while preserving hybrid image characteristic.
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    Combining Sketch and Tone for Pencil Drawing Production
    (The Eurographics Association, 2012) Lu, Cewu; Xu, Li; Jia, Jiaya; Paul Asente and Cindy Grimm
    We propose a new system to produce pencil drawing from natural images. The results contain various natural strokes and patterns, and are structurally representative. They are accomplished by novelly combining the tone and stroke structures, which complement each other in generating visually constrained results. Prior knowledge on pencil drawing is also incorporated, making the two basic functions robust against noise, strong texture, and significant illumination variation. In light of edge, shadow, and shading information conveyance, our pencil drawing system establishes a style that artists use to understand visual data and draw them. Meanwhile, it lets the results contain rich and well-ordered lines to vividly express the original scene.
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    Virtual Passepartouts
    (The Eurographics Association, 2012) Ritschel, Tobias; Templin, Krzysztof; Myszkowski, Karol; Seidel, Hans-Peter; Paul Asente and Cindy Grimm
    In traditional media, such as photography and painting, a cardboard sheet with a cutout (called passepartout) is frequently placed on top of an image. One of its functions is to increase the depth impression via the ''looking-through-a-window'' metaphor. This paper shows how an improved 3D effect can be achieved by using a virtual passepartout: a 2D framing that selectively masks the 3D shape and leads to additional occlusion events between the virtual world and the frame. We introduce a pipeline to design virtual passepartouts interactively as a simple post-process on RGB images augmented with depth information. Additionally, an automated approach finds the optimal virtual passepartout for a given scene. Virtual passepartouts can be used to enhance depth depiction in images and videos with depth information, renderings, stereo images and the fabrication of physical passepartouts
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    No Photos Harmed / Growing Paths from Seed - An Exhibition
    (The Eurographics Association, 2012) Colton, Simon; Ferrer, Blanca Perez; Paul Asente and Cindy Grimm
    We report on an exhibition centered around a dialogue between a Computational Creativity researcher presenting artwork generated by a computer program and a classically trained artist taking inspiration from the computational processes. The main purpose of the exhibition was to place software-generated art (where the program takes on some aesthetic and generative responsibilities, rather than acting as a mere tool) in both an art-production context and an art-historical context, by exploring the themes of creative responsibility and the loss of aura surrounding a work of art. A secondary purpose was to highlight the fact that computer generated art can be representational without relying on digital photographs as inputs. We describe certain technical hurdles we overcame in the production of the exhibition and the feedback we gained, in addition to elaborating on how the event and the project as a whole fits into an art-historical context. We conclude with brief details of another exhibition involving art generated by the same software system, where the notion of progression was explored; by describing a planned exhibition, where autonomy and independence in the system will be highlighted; and by providing a partial roadmap for progress towards autonomously creative software in the visual arts.
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    Consistent Stylization and Painterly Rendering of Stereoscopic 3D Images
    (The Eurographics Association, 2012) Northam, Lesley; Asente, Paul; Kaplan, Craig S.; Paul Asente and Cindy Grimm
    We present a method for stylizing stereoscopic 3D images that guarantees consistency between the left and right views. Our method decomposes the left and right views of an input image into discretized disparity layers and merges the corresponding layers from the left and right views into a single layer where stylization takes place. We then construct new stylized left and right views by compositing portions of the stylized layers. Because the left and right views come from the same source layers, our method eliminates common artifacts that cause viewer discomfort. We also present a stereoscopic 3D painterly rendering algorithm tailored to our layerbased approach. This method uses disparity information to assist in stroke creation so that strokes follow surface geometry without ignoring painted surface patterns. Finally, we conduct a user study that demonstrates that our approach to stereoscopic 3D image stylization leads to images that are more comfortable to view than those created using other techniques.
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    Active Strokes: Coherent Line Stylization for Animated 3D Models
    (The Eurographics Association, 2012) Benard, Pierre; Lu, Jingwan; Cole, Forrester; Finkelstein, Adam; Thollot, Joelle; Paul Asente and Cindy Grimm
    This paper presents a method for creating coherently animated line drawings that include strong abstraction and stylization effects. These effects are achieved with active strokes: 2D contours that approximate and track the lines of an animated 3D scene. Active strokes perform two functions: they connect and smooth unorganized line samples, and they carry coherent parameterization to support stylized rendering. Line samples are approximated and tracked using active contours (''snakes'') that automatically update their arrangment and topology to match the animation. Parameterization is maintained by brush paths that follow the snakes but are independent, permitting substantial shape abstraction without compromising fidelity in tracking. This approach renders complex models in a wide range of styles at interactive rates, making it suitable for applications like games and interactive illustrations.