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SECURE OBJECT-BASED CODINGVISUAL PRIVACY PROTECTION SOLUTION

University of TorontoMultimedia Labwww.dsp.utoronto.ca

Karl Martin kmartin@comm.utoronto.ca | www.dsp.utoronto.ca/~kmartin/

Prof. Kostas Plataniotiskostas@comm.utoronto.ca | www.dsp.utoronto.ca/~kostas/

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Outline

Technology Overview Object-Based Coding Secure Object-Based Coding

Privacy Protection Approach Example Application Scenario

Video Demonstration2

Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

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Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

Technology Overview Coding (compression) a necessary

component of most imaging systems for transmission/storage Several standards:

Still images: JPEG, JPEG2000, etc. Video: MPEG-(1/2/4), H.263, H.264, etc.

Object-Based Coding allows storage of arbitrarily shaped objects

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Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

Shape + Texture

Object is defined by shape and texture

Benefits of object-based coding: Allows intelligent processing of individual

objects Objects can have any semantic meaning and

be of arbitrary shape E.g.: face, body, car, suitcase, etc.

Coding schemes: MPEG-4, ST-SPIHT (UofT)

Technology Overview (cont’d)

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Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

Secure Object-Based Coding Combines encryption with object-based

coding Object texture (and optionally shape) is

confidential, enforced via private key Efficient encryption algorithm integrated

into coder, supporting real-time operation Encrypted objects completely obscured to

viewers without correct private key Provision of correct key allows perfect

recovery (decryption) of coded object

Technology Overview (cont’d)

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Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

Wavelet-based scheme for images and video

MPEG-4 -based scheme for video

Technology Overview (cont’d)

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Original

Object

Encrypted Object

(texture only)

Encrypted Object

(texture and shape)

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Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

Protect visual data of persons appearing in surveillance-style images/video Treat face or full body images as objects of

interest Code and encrypt objects separate from

background Reversible – Private decryption key to decrypt

face/body images provided based on appropriate authority

Background not encrypted – for “general” viewing

Privacy Protection Approach

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Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

Example Application Scenario

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Image/VideoCapture

Face/BodyDetection

ObjectSegmentation

Accurate or Rough Bounding Box

BackgroundImage/Video

Public/Low Level Personnel Viewing

Secure Object-Based

Coding

Secured Face/Body Objects

High LevelAuthority

Secure Decryption/Decoding

Decrypted Face/Body Objects

Storage

Storage

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Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

Example Application Scenario (cont’d)

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Original Sequence

Protected Sequence Protected Sequence(attempted access with

incorrect key)

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Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

Conclusion Secure object-based coding provides privacy

protection solution for images and video Arbitrarily-shaped objects such as face/body

can be coded and encrypted separate from background

Reversible encryption allows access to protected visual data with provision of secret decryption key

Efficient encryption approach supports real-time operation

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