SLAMorris Final Thesis After Corrections.pdf - Cranfield University

The results of the H3 identification method are in table 8.2, and the success rate
is shown in table 8.3. The results show a success rate of 75.5% for the method;
the rate reflects the amount of JPEG fragments which do not belong to the
thumbnail cache which contain markers not found in table 8.1. The markers
identified were the only ones found in the thumbnail cache file fragments
analysed.
8.6 A hybrid approach for thumbnail cache identification
The combined approach aims to take the strengths of each of the individual
methods and combine them to create a hybrid approach with improved
classification statistics. Whilst the bases of the combined approach are the
methods previously implemented in Chapter 7 other information is also added
to the individual approaches as appropriate to improve their performance. The
complete hybrid method takes in a cluster which comprises of 4096 bytes; the
method can also take disk images which once added are broken down into
4096 byte fragments to send to the identification method. Each cluster is
individually assessed for classification using the hybrid method. The method is
broken down into 6 testing stages. In general each testing stage is followed
sequentially, however depending on validation checks performed at each stage
a fragment may be classified or miss classification stages. If at any stage a
fragment is identified as not belonging to a thumbnail cache it is rejected and
categorised as H6. The process is summarised in figure 8.3; each stage of the
identification method is described below.
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