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Speaker |
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Date |
Nov 1, 2007 |
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Time |
2:30PM to 3:30PM |
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Place |
GRAIL (CSE 291) |
For the longest time, vector graphics representations were limited to
illustrations with flat or very simple shading. Vectorized
representations of photorealistic image content were largely prohibitive due to
the excessive number of vector primitives required to approximate realistic
image detail. Recently, several user-assisted, mesh-based methods have been
introduced to address this issue.
In this work, we present an alternative vector representation and vectorization system, based on multi-scale edges, with the
following advantages. Our system is fully automatic; no user-assistance is needed
to guide mesh placement and sub-division. Our vector representation is
intuitive; since edges occur at visible discontinuities within the image and
are thus directly linked to image content, their manipulation results in
predictable changes in the output image. Additionally, various edge-parameters
can be controlled individually, such as location and geometry, color, and width
(blur). Our vector representation is simple to manipulate; unlike mesh-based
approaches, each vectorized edge is independent of any
other edge. The edges, along with edge parameters, are encoded as simple splines, like those employed in most vector manipulation software.
Our representation is compact; as we only store information at edges, we are not
constrained by the arbitrary mesh topology of previous approaches. An integral
part of our initial image edge-analysis is a computation of edge-importance.
Usually, faint texture edges are less dominant than strong illumination edges.
The user can choose which edges to include in the representation (or which ones
to manipulate), based on their importance, thus allowing for a natural
level-of-detail control and powerful compactness vs. fidelity trade-off.
In addition, our representation encodes both color and gradient information
across edges. This allows us to offer various Poisson-based editing operations
for vector graphics that have previously been available only in raster
representations, such as texture transfer and seamless compositing. We
demonstrate our work with a complete end-to-end vectorization
and interactive editing solution, enabled by a real-time, GPU-based Poisson
solver.