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Automatic and Topology-Preserving Gradient Mesh Generation for Image Vectorization
"... Figure 1: Vectorization of an amulet with 21 holes, using a single topology-preserving gradient mesh. Gradient mesh vector graphics representation, used in commercial software, is a regular grid with specified position and color, and their gradients, at each grid point. Gradient meshes can compactly ..."
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Figure 1: Vectorization of an amulet with 21 holes, using a single topology-preserving gradient mesh. Gradient mesh vector graphics representation, used in commercial software, is a regular grid with specified position and color, and their gradients, at each grid point. Gradient meshes can compactly represent smoothly changing data, and are typically used for single objects. This paper advances the state of the art for gradient meshes in several significant ways. Firstly, we introduce a topology-preserving gradient mesh representation which allows an arbitrary number of holes. This is important, as objects in images often have holes, either due to occlusion, or their 3D structure. Secondly, our algorithm uses the concept of image manifolds, adapting surface parameterization and fitting techniques to generate the gradient mesh in a fully automatic manner. Existing gradient-mesh algorithms require manual interaction to guide grid construction, and to cut objects with holes into disk-like regions. Our new algorithm is empirically at least 10 times faster than previous approaches. Furthermore, image segmentation can be used with our new algorithm to provide automatic gradient mesh generation for a whole image. Finally, fitting errors can be simply controlled to balance quality with storage.
A Subdivision-Based Representation for Vector Image Editing
"... Vector graphics has been employed in a wide variety of applications due to its scalability and editability. Editability is a high priority for artists and designers who wish to produce vector-based graphical content with user interaction. In this paper, we introduce a new vector image representatio ..."
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Cited by 5 (0 self)
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Vector graphics has been employed in a wide variety of applications due to its scalability and editability. Editability is a high priority for artists and designers who wish to produce vector-based graphical content with user interaction. In this paper, we introduce a new vector image representation based on piecewise smooth subdivision surfaces, which is a simple, unified and flexible framework that supports a variety of operations, including shape editing, color editing, image stylization, and vector image processing. These operations effectively create novel vector graphics by reusing and altering existing image vectorization results. Because image vectorization yields an abstraction of the original raster image, controlling the level of detail of this abstraction is highly desirable. To this end, we design a feature-oriented vector image pyramid that offers multiple levels of abstraction simultaneously. Our new vector image representation can be rasterized efficiently using GPU-accelerated subdivision. Experiments indicate that our vector image representation achieves high visual quality and better supports editing operations than existing representations.
Curve Structure Extraction for Cartoon Images
- THE 5TH JOINT CONFERENCE ON HARMONIOUS HUMAN MACHINE ENVIRONMENT (HHME)
, 2009
"... We propose a novel method for curve structure extraction of cartoon images. Our method handles two types of cartoon curves, decorative curves and boundary curves, in a uniform way. The method consists of two steps. First, we calculate curve points by applying non-maximal suppress on secondary deriva ..."
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We propose a novel method for curve structure extraction of cartoon images. Our method handles two types of cartoon curves, decorative curves and boundary curves, in a uniform way. The method consists of two steps. First, we calculate curve points by applying non-maximal suppress on secondary derivative of cartoon images. Second, these curve points are linked together to form structure curves while unreliable curves are removed away. Compared to curve structure extraction algorithm proposed by Steger, the number of curves generated by our algorithm is only 19% of Steger’s on average, with better curve quality. Furthermore, more accurate curve position can be obtained by our method.
Topology-Driven Vectorization of Clean Line Drawings
"... Vectorization provides a link between raster scans of pencil-andpaper drawings and modern digital processing algorithms that require accurate vector representations. Even when input drawings are comprised of clean, crisp lines, inherent ambiguities near junctions make vectorization deceptively diffi ..."
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Cited by 4 (0 self)
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Vectorization provides a link between raster scans of pencil-andpaper drawings and modern digital processing algorithms that require accurate vector representations. Even when input drawings are comprised of clean, crisp lines, inherent ambiguities near junctions make vectorization deceptively difficult. As a consequence, current vectorization approaches often fail to faithfully capture the junctions of drawn strokes. We propose a vectorization algorithm specialized for clean line drawings that analyzes the drawing’s topology in order to overcome junction ambiguities. A gradientbased pixel clustering technique facilitates topology computation. This topological information is exploited during centerline extraction by a new “reverse drawing” procedure that reconstructs all possible drawing states prior to the creation of a junction and then selects the most likely stroke configuration. For cases where the automatic result does not match the artist’s interpretation, our drawing analysis enables an efficient user interface to easily adjust the junction location. We demonstrate results on professional examples and evaluate the vectorization quality with quantitative comparison to hand-traced centerlines as well as the results of leading commercial algorithms.
Online Video Stream Abstraction and Stylization
"... Abstract—This paper gives an automatic method for online video stream abstraction, producing a temporally coherent output video stream, in the style with large regions of constant color and highlighted bold edges. Our system includes two novel components. Firstly, to provide coherent and simplified ..."
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Abstract—This paper gives an automatic method for online video stream abstraction, producing a temporally coherent output video stream, in the style with large regions of constant color and highlighted bold edges. Our system includes two novel components. Firstly, to provide coherent and simplified output, we segment frames, and use optical flow to propagate segmentation information from frame to frame; an error control strategy is used to help ensure that the propagated information is reliable. Secondly, to achieve coherent and attractive coloring of the output, we use a color scheme replacement algorithm specifically designed for an online video stream. We demonstrate real-time performance for CIF videos, allowing our approach to be used for live communication and other related applications. Index Terms—Abstraction, color scheme replacement, optical flow, segmentation, temporal coherence, video stream. I.
EXCOL: An EXtract-and-COmplete Layering Approach to Cartoon Animation Reusing
"... Abstract—We introduce the EXCOL method (EXtract-and-COmplete Layering) — a novel cartoon animation processing technique to convert a traditional animated cartoon video into multiple semantically meaningful layers. Our technique is inspired by vision-based layering techniques but focuses on shape cu ..."
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Abstract—We introduce the EXCOL method (EXtract-and-COmplete Layering) — a novel cartoon animation processing technique to convert a traditional animated cartoon video into multiple semantically meaningful layers. Our technique is inspired by vision-based layering techniques but focuses on shape cues in both the extraction and completion steps to reflect the unique characteristics of cartoon animation. For layer extraction, we define a novel similarity measure incorporating both shape and color of automatically segmented regions within individual frames and propagate a small set of user-specified layer labels among similar regions across frames. By clustering regions with the same labels, each frame is appropriately partitioned into different layers, with each layer containing semantically meaningful content. Then a warping-based approach is used to fill missing parts caused by occlusion within the extracted layers to achieve a complete representation. EXCOL provides a flexible way to effectively reuse traditional cartoon animations with only a small amount of user interaction. It is demonstrated that our EXCOL method is effective and robust, and the layered representation benefits a variety of applications in cartoon animation processing. Index Terms—cartoon animation, layer extraction, layer completion, label propagation 1
Recognizing text elements for svg comic compression and its novel applications
- In Proceedings of the 2011 International Conference on Document Analysis and Recognition, ICDAR ’11
, 2011
"... Abstract—SVG (scalable vector graphics) has become the standard format for 2D graphics in HTML5. Although some image-to-SVG conversion systems had been proposed, the sizes of files they produced are still large. In [1], we proposed a new system to convert raster comic images into vector SVG files. T ..."
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Abstract—SVG (scalable vector graphics) has become the standard format for 2D graphics in HTML5. Although some image-to-SVG conversion systems had been proposed, the sizes of files they produced are still large. In [1], we proposed a new system to convert raster comic images into vector SVG files. The compression ratio is better than the previous methods. However, these methods do not process text in raster images. In this paper, we improve our system to recognize text elements in the comic and use these text elements to provide better compression and novel applications. The proposed method uses SCW (sliding concentric windows) and SVM (support vector machine) to identify text regions. Then, OCR (optical character recognition) is applied to recognize text elements in those regions. Instead of encoding the text regions as vectors, the text elements are embedded in the SVG file along with their coordinate values. Experimental results show that we can reduce the file sizes to about 52 % of the original SVG files. Using these text elements, we can translate comics into other languages to provide multilingual services easily. Text/content-based image search can be supported efficiently. It can also provide a novel application system for story teller. Keywords- text detection, SVG, vector compression, SCW segmentation I.
Rights IEEE Transactions on Visualization and Computer Graphics.Copyright © IEEE A Subdivision-Based Representation for Vector Image Editing
"... Abstract—Vector graphics has been employed in a wide variety of applications due to its scalability and editability. Editability is a high priority for artists and designers who wish to produce vector-based graphical content with user interaction. In this paper, we introduce a new vector image repre ..."
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Abstract—Vector graphics has been employed in a wide variety of applications due to its scalability and editability. Editability is a high priority for artists and designers who wish to produce vector-based graphical content with user interaction. In this paper, we introduce a new vector image representation based on piecewise smooth subdivision surfaces, which is a simple, unified and flexible framework that supports a variety of operations, including shape editing, color editing, image stylization, and vector image processing. These operations effectively create novel vector graphics by reusing and altering existing image vectorization results. Because image vectorization yields an abstraction of the original raster image, controlling the level of detail of this abstraction is highly desirable. To this end, we design a feature-oriented vector image pyramid that offers multiple levels of abstraction simultaneously. Our new vector image representation can be rasterized efficiently using GPU-accelerated subdivision. Experiments indicate that our vector image representation achieves high visual quality and better supports editing operations than existing representations. Index Terms—Vector graphics, subdivision surfaces, multiresolution representation, vector image editing Ç 1
CS 838: Advanced Graphics Project 1: Stylized Editable Vectorizations
, 2009
"... The goal of this project was the creation of simple, recognizable and easily editable vectorized representations of real-world image inputs. Towards this goal I implemented a novel vectorization system using the combination of two preexisting, but relatively new, algorithms- one for image abstractio ..."
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The goal of this project was the creation of simple, recognizable and easily editable vectorized representations of real-world image inputs. Towards this goal I implemented a novel vectorization system using the combination of two preexisting, but relatively new, algorithms- one for image abstraction and simplification, one for segmentation and vectorization of abstract or cartoon images. I also experimented with methods of detecting occlusion and filling holes in the vectorized result, with a qualitative goal of simplifying the steps necessary to modify or delete regions within the image and produce a visually consistent result. 1 Image Abstraction The first step in my method stylizes and abstracts the input image to a form better suited for vectorization. For this I use the shape-simplifying abstraction technique of Kang and Lee [2]. Their method involves the iterative application of the evolution equation where It = s · κ| | ▽ I| | (1) κ = I2 xIyy − 2IxIyIxy + I 2 xIxx
CTU in Prague, FEE
"... Figure 1: An example of output from our system: texture-mapped hand-drawn cartoon enhanced by 3D-like effects. We present a novel and practical texture mapping algorithm for hand-drawn cartoons that allows the production of visually rich animations with minimal user effort. Unlike previous technique ..."
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Figure 1: An example of output from our system: texture-mapped hand-drawn cartoon enhanced by 3D-like effects. We present a novel and practical texture mapping algorithm for hand-drawn cartoons that allows the production of visually rich animations with minimal user effort. Unlike previous techniques, our approach works entirely in the 2D domain and does not require the knowledge or creation of a 3D proxy model. Inspired by the fact that the human visual system tends to focus on the most salient features of a scene, which we observe for hand-drawn cartoons are the contours rather than the interior of regions, we can create the illusion of temporally coherent animation using only rough 2D image registration. This key observation allows us to design a simple yet effective algorithm that significantly reduces the amount of manual labor required to add visually complex detail to an animation, thus enabling efficient cartoon texturing for computer-assisted animation production pipelines. We demonstrate our technique on a variety of input animations as well as provide examples of postprocessing operations that can be applied to simulate 3D-like effects entirely in the 2D domain. 1
