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on \emph{texture discrimination}, the ability of human observers to |
on \emph{texture discrimination}, the ability of human observers to |
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discriminate pairs of textures. |
discriminate pairs of textures. |
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The term is often used interchangably with \emph{texture segregation}, |
The term is often used interchangably with \emph{texture segregation}, |
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the more specific task of finding the border between areas of |
the more specific task of finding the border between differently textured |
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different textures (different phases of local characteristics at the |
areas (different phases of local characteristics at the |
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border can segregate otherwise indiscriminable textures). |
border can segregate otherwise indiscriminable textures). |
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First experiments on computer-generated, unnatural textures in the 60s |
First experiments on computer-generated, unnatural textures in the 60s |
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\cite{julesz62visualpattern} led to proposals of discrimination models |
\cite{julesz62visualpattern} led to proposals of discrimination models |
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based on $N$th-order statistics (the joint distributions of all |
based on the $N$th-order statistics of textures |
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$N$-tuples of pixels for given $N$) and connectivity structures of |
(the joint distributions of the values at the corners of a randomly |
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certain micropatterns. |
placed (translated) $N$-gon for all different $N$-gons). |
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%and connectivity structures of certain micropatterns. |
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Statistical modeling of textures as samples from a probability |
Statistical modeling of textures as samples from a probability |
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distribution on a random field as already seen in \cite{julesz62visualpattern} |
distribution on a random field as already seen in \cite{julesz62visualpattern} |
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depends only on the values of its neighborhood (local characteristics). |
depends only on the values of its neighborhood (local characteristics). |
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XXX: resolution-dependency? |
XXX: resolution-dependency? |
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Attempt to explain texture perception by the densities of textons |
Attempt to explain texture discrimination by the densities of textons |
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\cite{julesz81textons}, fundamental texture elements, such as |
\cite{julesz81textons}, fundamental texture elements, such as |
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elongated blobs, line terminators, line crossings, etc. |
elongated blobs, line terminators, line crossings, etc. |
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However, the textons are hard to define formally. |
However, the textons are hard to define formally. |
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Of course, such models are not directly applicable on high-resolution |
Much simpler filtering-based models can explain texture discrimination |
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textures; some kind of filtering would be required to obtain the input. |
just as well \cite{bergen88earlyvision}. |
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However, the filtering itself can also have good explanatory power |
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\cite{bergen88earlyvision}.XXX |
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Filtering based approach, e.g., \cite{heeger95pyramid}. |
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Essentially a bank of linear filters is applied to the texture followed |
Essentially a bank of linear filters is applied to the texture followed |
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by a nonlinearity and then another set of filters. |
by a nonlinearity and then another set of filters. |
282 |
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In \cite{heeger95pyramid}, new textures with appearance similar |
283 |
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to a given texture are created by matching certain histograms |
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of filter responses. |
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Mapping texture appearance to an Euclidian texture space |
Mapping texture appearance to an Euclidian texture space |
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(see \cite{gurnsey01texturespace} and the references therein): |
(see \cite{gurnsey01texturespace} and the references therein): |
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(no color, lack of frequency-band interaction, etc.). |
(no color, lack of frequency-band interaction, etc.). |
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For some natural texture sets (see, e.g., \cite{rao96texturenaming}), |
For some natural texture sets (see, e.g., \cite{rao96texturenaming}), |
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three dimensions have also been |
three dimensions have also been |
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sufficient, but often the semantic connections cause the |
sufficient, but often semantic connections cause the |
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similarity to be context-dependant, making it hard to assess the |
similarity to be context-dependant, making it hard to assess the |
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dimensionality. |
dimensionality. |
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% XXX: this is something we should experiment with our textures |
% XXX: this is something we should experiment with our textures |
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XXX: physiological knowledge of visual perception |
XXX: physiological knowledge of visual perception |
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304 |
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XXX: in most work, texture is considered as the output of a stochastic |
305 |
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process that produces certain repeating features. |
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Different samples from the process are considered as the same texture. |
307 |
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The textures created by our algorithm, although repeating, are more like |
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complete images rather than microstructure. |
309 |
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Therefore, higher level processes of vision are also involved |
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in the perception and recognition. |
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\subsection{Focus+Context views} |
\subsection{Focus+Context views} |
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Focus+Context, or, fisheye views\cite{fc-fisheye} are |
Focus+Context, or, fisheye views\cite{fc-fisheye} are |