Large-Scale Image Retrieval: Visual Object Recognition and Instance Retrieval, Lecture notes of Computer Science

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Large-scale Instance Retrieval

Computer Vision

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Multi-view matching

vs

Matching two given

views for depth

Search for a matching

view for recognition

Kristen GraumanDocsity.com

Perceptual and Sensory Augmented ComputingVisual Object Recognition Tutorial

Video Google System

1. Collect all words within

query region

2. Inverted file index to find

relevant frames

3. Compare word counts

4. Spatial verification

Sivic & Zisserman, ICCV 2003

• Demo online at : http://www.robots.ox.ac.uk/~vgg/r esearch/vgoogle/index.html

Query region

Retrieved frames

Kristen GraumanDocsity.com

Perceptual and Sensory Augmented ComputingVisual Object Recognition Tutorial

B. Leibe

Example Applications

Mobile tourist guide

• Self-localization
• Object/building recognition
• Photo/video augmentation

[Quack, Leibe, Van Gool, CIVR’08]Docsity.com

Perceptual and Sensory Augmented ComputingVisual Object Recognition TutorialVisual Object Recognition Tutorial

Web Demo: Movie Poster Recognition

http://www.kooaba.com/en/products_engine.html#

50’000 movie posters indexed

Query-by-image from mobile phone available in Switzer- land

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Application: Image Auto-Annotation

K. Grauman, B. Leibe 18

Left: Wikipedia image

Right: closest match from Flickr

[Quack CIVR’08]

Moulin Rouge

Tour Montparnasse Colosseum

Viktualienmarkt

Maypole

Old Town Square (Prague)

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Indexing local features

• Each patch / region has a descriptor, which is a

point in some high-dimensional feature space

(e.g., SIFT)

Descriptor’s

feature space

Kristen GraumanDocsity.com

Indexing local features

• When we see close points in feature space, we

have similar descriptors, which indicates similar

local content.

Descriptor’s

feature space

Database

images

Query

image

Easily can have millions of

features to search! Docsity.comKristen Grau

Visual words

• Map high-dimensional descriptors to tokens/words

by quantizing the feature space

Descriptor’s feature space

• Quantize via

clustering, let

cluster centers be

the prototype

“words”

• Determine which

word to assign to

each new image

region by finding

the closest cluster

center.

Word #

Kristen GraumanDocsity.com

Visual words

• Example: each

group of patches

belongs to the

same visual word

Figure from Sivic & Zisserman, ICCV 2003 (^) Kristen GraumanDocsity.com

Inverted file index

• Database images are loaded into the index mapping

words to image numbers

Kristen GraumanDocsity.com

• New query image is mapped to indices of database

images that share a word.

Inverted file index

Kristen GraumanDocsity.com

Analogy to documents

Of all the sensory impressions proceeding to the brain, the visual experiences are the dominant ones. Our perception of the world around us is based essentially on the messages that reach the brain from our eyes. For a long time it was thought that the retinal image was transmitted point by point to visual centers in the brain; the cerebral cortex was a movie screen, so to speak, upon which the image in the eye was projected. Through the discoveries of Hubel and Wiesel we now know that behind the origin of the visual perception in the brain there is a considerably more complicated course of events. By following the visual impulses along their path to the various cell layers of the optical cortex, Hubel and Wiesel have been able to demonstrate that the message about the image falling on the retina undergoes a step- wise analysis in a system of nerve cells stored in columns. In this system each cell has its specific function and is responsible for a specific detail in the pattern of the retinal image.

sensory, brain, visual, perception, retinal, cerebral cortex, eye, cell, optical nerve, image Hubel, Wiesel

China is forecasting a trade surplus of $90bn (£51bn) to $100bn this year, a threefold increase on 2004's $32bn. The Commerce Ministry said the surplus would be created by a predicted 30% jump in exports to $750bn, compared with a 18% rise in imports to $660bn. The figures are likely to further annoy the US, which has long argued that China's exports are unfairly helped by a deliberately undervalued yuan. Beijing agrees the surplus is too high, but says the yuan is only one factor. Bank of China governor Zhou Xiaochuan said the country also needed to do more to boost domestic demand so more goods stayed within the country. China increased the value of the yuan against the dollar by 2.1% in July and permitted it to trade within a narrow band, but the US wants the yuan to be allowed to trade freely. However, Beijing has made it clear that it will take its time and tread carefully before allowing the yuan to rise further in value.

China, trade, surplus, commerce, exports, imports, US, yuan, bank, domestic, foreign, increase, trade, value

ICCV 2005 short course, L. Fei-FeiDocsity.com

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