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Re: [help-GIFT] Colour blocks


From: David Squire
Subject: Re: [help-GIFT] Colour blocks
Date: Sat, 23 Aug 2003 10:19:10 +1000
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Madhvi WAHI wrote:

Hi,

According to the paper--"Content-based query of image databases, inspirations 
from text retrieval: inverted files, frequency-based weights  and releevance
feedback; two sets of features are extracted from the quantized HSV colour
space, the first, a colour histogram and the second, colour blocks.

Are the colour blocks the same as histograms, that is, once the images are 
divided at four scales, are histograms calculated for each of these four
regions, to record the local information? Also, what is the meaning of mode 
colour being calculated for each block?
Have another look at the paper:

<http://www.csse.monash.edu.au/%7Edavids/publications/postscript/1999/SquireMuellerMuellerRaki_scia99.pdf> David McG. Squire, Wolfgang Müller, Henning Müller and Jilali Raki, Content-based query of image databases, inspirations from text retrieval: inverted files, frequency-based weights and relevance feedback <http://www.csse.monash.edu.au/%7Edavids/publications/postscript/1999/SquireMuellerMuellerRaki_scia99.ps.gz>, In The 11th Scandinavian Conference on Image Analysis (SCIA'99), Kangerlussuaq, Greenland, pp. 143-149, June 7-11 1999.

which is available via http://www.csse.monash.edu.au/~davids/publications/. In section 3.2, it says

"The image is divided into square blocks at four scales, ranging from 16 x 16 through to 128 x 128. The mode colour is calculated for each block. The occurrence of of a given color in a particular block is treated as a binary feature. For our 256 x 256 images there are thus 56440 possible colour block features, of which each image has 340."

Note that there are 340 colour block features per image (4 + 16 + 64 + 256 = 340). In the collection, the mode colour of each block can be any of 166 colours, so there are 340 x 166 = 56440 possible colour block features.

"Mode" is a statistical term, just like "mean" and "median". See http://mathworld.wolfram.com/Mode.html

Regards,

David

--
Dr. David McG. Squire, Postgraduate Research Coordinator (Caulfield),
Computer Science and Software Engineering, Monash University, Australia
http://www.csse.monash.edu.au/~davids/






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