6. Velpas technology
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Bag of Visual Word approach
with in-house implementation
of key algorithms
– Lightweight local descriptors –
32-bit integer visual word
– Fast geometric verification
7. Indexing
• Pyramid of orientations
and segmentation tree
for detection of low-
level “syllables”
• Aggregation of low-level
“syllables” to high-level
“words”
• Inverted index for word-
to-image mapping
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8. Retrieval
• Query representation is
the same as for
collection image
• TF*IDF scoring of
collection images
• Geometric verification of
highest-scored images
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