<s5>Æliens</s5> -- slide(s)

image query

obtaining descriptive information
establishing similarity

content-based description

objects in image
shape descriptor -- shape/region of object
property description -- cells in image

shape

bounding box -- (XLB,XUB,YLB,YUB)

property

property -- name=value

example


  shape descriptor: XLB=10; XUB=60; YLB=3; YUB=50   (rectangle)  
  property descriptor: pixel(14,7): R=5; G=1; B=3

definitions

image grid: $(m * n)$ cells of equal size
cell property: (Name, Value, Method)

example


  property: (bwcolor,{b,w},bwalgo)

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similarity-based retrieval

How do we determine whether the content of a segment (of a segmented image) is similar to another image (or set of images)?

solutions

metric approach -- distance between two image objects
transformation approach -- relative to specification

metric approach

distance $d:X->[0,1]$ is distance measure if:


           d(x,y) = d(y,x)
  	 d(x,y)  $<=$  d(x,z) + d(z,y)
  	 d(x,x) = 0

pixel properties

objects with pixel properties $p_1,...,p_n$
pixels: $(x,y,v1,...,v_n)$
object contains w x h (n+2)-tuples

complexity

a set of points in k-dimensional space for k = n + 2

feature extraction

maps object into s-dimensional space

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transformation approach

Given two objects o1 and o2, the level of dissimilarity is proportional to the (minimum) cost of transforming object o1 into object o2 or vice versa

transformation operators


    $to_1,...,to_r$  -- translation, rotation, scaling

cost

$cost(TS) = %S_{i=1}^{r} cost(to_{i})$

distance

$d(o,o') = min { cost(TS) | TS in TSeq(o,o') }$

advantages

user-defined similarity -- choice of transformation operators
user-defined cost-function

operations


   rotate(image-id,dir,angle)
   segment(image-id, predicate)
   edit(image-id, edit-op)

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image repository

storage -- unsegmented images
description -- limited set of features
index -- feature-based index
retrieval -- distance between feature vectors

mission

Our goal is to study aspects of the deployment and architecture of virtual environments as an interface to (intelligent) multimedia information systems ...

Æliens

2009

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solutions

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