SUPPORTING LANDMARK IMAGE RETRIEVAL WITH SKYLINE

EXTRACTION TECHNIQUES Date : 2012 / 04 / 12資訊碩一 10077034 蔡勇儀 @ LAB603

Outline Introduction Preliminaries Method Experimental result Conclusions

Introduction Image retrieval have more challenge

than text retrieval.

Use low-level feature to identify objects is non-trivial.

Skyline is a good feature to identify landmark contour.

Outline Introduction Preliminaries Method Experimental result Conclusions

Traditional image retrieval Traditional techniques for image retrieval

rely on some metadata (i.e., keywords or captions of image)

It isn’t a good method for practical applications since it is labor intensive and need more space.

Content-based image retrieval Content-based image retrieval(CBIR) is

using image’s feature for retrieval.

Query-by-example Query-by-sketch

Relevance feedback technique

Identifying landmarks with skylines Region-growing-based

Using same color region extend find the skylines Weak robustness on the sky with cloud or

complex background

Edge-based Edge detection Retaining the points which are luminous intensity

change sharply Using other method to find clear skyline.

Outline Introduction Preliminaries Method Experimental result Conclusions

Method(1/4) - Difficulties Small portion of edge points constitute

the proper skyline.

Skyline may not fully-connected.

Steep or tortuous.

Method(2/4) - RON RON(radius of neighborhood)

Defining the search region (ex. RON = 2 -> grid zone = 5*5) Solving the difficulties.

Method(3/4) – Direction priority Using clockwise

Good direction for traversal skyline.

Method(4/4) – Find the skyline Using Sobel Filter for edge detection Using DFS for search. (Need decide the

start point?)

Outline Introduction Preliminaries Method Experimental result Conclusions

Experimental Result DP VS This method ( O(n2) & O(n) )

Outline Introduction Preliminaries Method Experimental result Conclusions

Conclusions This is a feasible for landmark image retrieval.

If there are more line cross the image?

If sky have complex object(ex. Light or cloud…)?

If the beginning point is not in skyline?

More problem need to solving…

Thank for your listening! Q&A