SLAMorris Final Thesis After Corrections.pdf - Cranfield University

make less conservative judgements about the relevance of websites when
presented with a visual thumbnail. The visual thumbnail provides the user with
an opportunity to assess the layout of a webpage and identify characteristics
which may show whether it is suitable such as colour and graphics.
Photographic software such as Photoshop and iPhoto contain thumbnail caches
which assist in the viewing of large quantities of images. These caches are built
to provide quick access and minimise the use of system resources
2.4.2 Operating system Thumbnail Caches
In Windows XP, thumbnail caches are located in every directory which has
been viewed using the thumbnail display option in Windows explorer (providing
the option to cache thumbnails has not been manually turned off by the user).
Each thumbnail cache consists of a single binary file called ‘thumbs.db’, which
uses the OLE2 container format [Roukine, 2012]. Each thumbnail cache stores
information on the files within that directory, and may continue to store the
information after the files have been deleted. A variety of files types may have
associated visual thumbnails stored in the thumbnail cache, such as Microsoft
Office Documents, these show the first page or slide of these documents. The
thumbnails are stored within record entries in the catalog stream of the OLE2
container; the records are stored in a red-black binary tree structure, which
allows fast access to each thumbnail when the operating system requires it.
The maximum size of a single visual thumbnail stored within the thumbs.db
cache is 256 x 256 pixels; the size is not large enough to read individual lines of
text but it can allow a match to be made with the layout of the original
document. The thumbnail cache also contains various metadata such as file
name, path and modification time; the metadata can assist in showing a
relationship between the creating file and the thumbnail. The OLE2 structure is
also used with the Microsoft Office Suite (versions 6-12). From Office
2007saving in the binary structure was an option, an XML structure was also
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