Secure Object-based Coding v isual Privacy protection solution

1. Secure Object-based Codingvisual Privacy protection solution University of Toronto Multimedia Lab www.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/

2. Outline • Technology Overview • Object-Based Coding • Secure Object-Based Coding • Privacy Protection Approach • Example Application Scenario • Video Demonstration Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

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

4. Technology Overview (cont’d) • 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) + Texture Shape Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

5. Technology Overview (cont’d) • 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 Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

6. Technology Overview (cont’d) • Wavelet-based scheme for images and video • MPEG-4 -based scheme for video OriginalObject Encrypted Object(texture only) Encrypted Object(texture and shape) Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

7. Privacy Protection Approach • 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 keyto decrypt face/body images provided based on appropriate authority • Background not encrypted – for “general” viewing Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

8. Example Application Scenario Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

9. Example Application Scenario (cont’d) Original Sequence Protected Sequence(attempted access with incorrect key) Protected Sequence Secure Object-Based Coding – Visual Privacy Protection Solution – University of Toronto

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