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A Sample Recognition Problem. Joseph Tighe University of North Carolina at Chapel Hill. What is recognition?. What is recognition?. What is recognition?. What is recognition?. Figure from Shotton et al. (2009). - PowerPoint PPT Presentation
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A SAMPLE RECOGNITION PROBLEM
Joseph Tighe University of North Carolina at Chapel Hill
What is recognition?
What is recognition?
What is recognition?
What is recognition?
He et al. (2004), Hoiem et al. (2005), Shotton et al. (2006, 2008, 2009), Verbeek and Triggs (2007), Rabinovich et al. (2007), Galleguillos et al. (2008), Gould et al. (2009), etc.
Figure from Shotton et al. (2009)
What is recognition? Have some entity
photo bounding box in photo pixel
Assign semantic meaning scene type, tags, sentence object label, action semantic class, material, geometric
orientation
Our Problem Entity: Images Goal: Assign 1 of 4 labels (airplane, car,
face, motorbike
Finding Similar Images
Ocean
Open Field
Highway
Street
Forest
Mountain
Inner City
Tall BuildingWhat is depicted in this image?
Which image is most similar?
Then assign the label from the most similar image
Pixels are a bad measure of similarity
Most similar according to pixel distance Most similar according to “Bag of Words”
Origin of the Bag of Words model
Orderless document representation: frequencies of words from a dictionary Salton & McGill (1983)
US Presidential Speeches Tag Cloudhttp://chir.ag/phernalia/preztags/
What are words for an image?
Wing Tail
WheelBuildingPropeller
Wing TailWheelBuildingPropeller Jet Engine
Wing TailWheelBuildingPropeller Jet Engine
Wing TailWheelBuildingPropeller Jet Engine
But where do the words come from?
Then where does the dictionary come from?
Example Dictionary
Source: B. Leibe
Another dictionary
………
…
Source: B. Leibe
Fei-Fei et al. 2005
Outline of the Bag of Words method
Divide the image into patches Assign a “word” for each patch Count the number of occurrences of
each “word” in the image
Matlab Demo