Category Archives: Object Recognition

Bag of Words Models for visual categorization

Lately, I’ve been reading a lot about BOW (Bag of Words) models [1] and I thought it would be nice to write a short post on the subject. The post is based on the slides from Li Fei-Fei taken from ICCV 2005 course about object detection:

As the name implies, the concept of BOW is actually taken from text analysis. The idea is to represent a document as a “bag” of important keywords, without ordering of the words (that’s why it’s a called “bag of words”, instead of a list for example).

Illustration of Bag of words model in documents

Illustration of Bag of words model in documents

In computer vision, the idea is similar. We represent an object as a bag of visual words – patches that described by a certain descriptor:

Illustration of Bag of words model in images

Illustration of Bag of words model in images

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