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  • Exposing Photo Manipulation with

    Geometric Inconsistencies James F. O’Brien

    U.C. Berkeley

    Collaborators

    Hany Farid Eric Kee Valentina Conotter Stephen Bailey

    1 image-forensics-PG14.key - October 9, 2014

  • Communication by Images

    2-1 image-forensics-PG14.key - October 9, 2014

  • Communication by Images

    2-2 image-forensics-PG14.key - October 9, 2014

  • Image Manipulation

    Iranian missile test, 2008

    3-1 image-forensics-PG14.key - October 9, 2014

  • Image Manipulation

    Iranian missile test, 2008

    3-2 image-forensics-PG14.key - October 9, 2014

  • Image Manipulation

    Iranian stealth fighter, 2013

    4-1 image-forensics-PG14.key - October 9, 2014

  • Image Manipulation

    Iranian stealth fighter, 2013

    4-2 image-forensics-PG14.key - October 9, 2014

  • Image Manipulation

    Economist manipulates image of Obama, 2010

    5-1 image-forensics-PG14.key - October 9, 2014

  • Image Manipulation

    Economist manipulates image of Obama, 2010

    5-2 image-forensics-PG14.key - October 9, 2014

  • Image Manipulation

    Fabricated image of John Kerry and Jane Fonda, 2004

    6-1 image-forensics-PG14.key - October 9, 2014

  • Image Manipulation

    Fabricated image of John Kerry and Jane Fonda, 2004

    6-2 image-forensics-PG14.key - October 9, 2014

  • Video Manipulation

    Flying Birdman Hoax, 2012

    7-1 image-forensics-PG14.key - October 9, 2014

  • Video Manipulation

    Flying Birdman Hoax, 2012

    7-2 image-forensics-PG14.key - October 9, 2014

  • Historical Image Manipulation

    •Image manipulation as old as photography

    •Primitive techniques work surprisingly well

    Library of Congress archive

    photo of Abraham Lincoln

    1826

    8-1 image-forensics-PG14.key - October 9, 2014

  • Historical Image Manipulation

    •Image manipulation as old as photography

    •Primitive techniques work surprisingly well

    Library of Congress archive

    photo of Abraham Lincoln

    1826

    8-2 image-forensics-PG14.key - October 9, 2014

  • Historical Image Manipulation

    9-1 image-forensics-PG14.key - October 9, 2014

  • Historical Image Manipulation

    9-2 image-forensics-PG14.key - October 9, 2014

  • Image Forensics

    •Detect forgeries

    •Detect signs of manipulation

    •Prove image was modified in some way

    •Cannot prove an image unmodified

    !

    •Suite of detection tools

    •Individual methods can be countered by informed attacker

    •Individual tools may not apply in all cases

    •Each additional method makes forgery harder

    10 image-forensics-PG14.key - October 9, 2014

  • Advantage: Forgers

    •People:

    •Good at understanding scene content

    •Poor at noticing many types of inconsistencies

    •Simple manipulation methods work well

    •New manipulation methods being developed

    11 image-forensics-PG14.key - October 9, 2014

  • Example Inconsistency

    N = 20; RT = 7.6s Farid and Bravo 2010

    Selected as correct: 62.1% Selected as correct: 50.1%

    12 image-forensics-PG14.key - October 9, 2014

  • Things we don’t see

    13 image-forensics-PG14.key - October 9, 2014

  • Things we don’t see

    14 image-forensics-PG14.key - October 9, 2014

  • Advantage: Forgers

    •People:

    •Good at understanding scene content

    •Poor at noticing many types of inconsistencies

    •Simple manipulation methods work well

    •New manipulation methods being developed

    15 image-forensics-PG14.key - October 9, 2014

  • Image Forensics •Format Methods

    •EXIF meta data

    •Quantization tables

    •Coding decisions

    •Signatures or watermarks

    •Pixel Methods •Linear dependance

    •Bayer pattern artifacts

    •Chromatic aberration

    •Compression artifacts

    •Not tied to scene content

    •Easy to apply

    •Easy to fool (informed attacker)

    •Not robust to common operations

    16 image-forensics-PG14.key - October 9, 2014

  • Image Forensics

    •Geometric methods •Content inconsistencies

    •Require human annotation

    •Computer analysis

    •Examples:

    •Shadows

    •Lighting

    •Reflections

    17 image-forensics-PG14.key - October 9, 2014

  • Geometric Image Forensics

    •Not same as Computer Vision •Possibly user involved in loop •Only looking for inconsistencies only •Don’t need to fully extract scene content

    18 image-forensics-PG14.key - October 9, 2014

  • 19 image-forensics-PG14.key - October 9, 2014

  • 20 image-forensics-PG14.key - October 9, 2014

  • 21 image-forensics-PG14.key - October 9, 2014

  • 22 image-forensics-PG14.key - October 9, 2014

  • 23 image-forensics-PG14.key - October 9, 2014

  • 24 image-forensics-PG14.key - October 9, 2014

  • 25 image-forensics-PG14.key - October 9, 2014

  • 26 image-forensics-PG14.key - October 9, 2014

  • 27 image-forensics-PG14.key - October 9, 2014

  • 28 image-forensics-PG14.key - October 9, 2014

  • 29 image-forensics-PG14.key - October 9, 2014

  • 30 image-forensics-PG14.key - October 9, 2014

  • 31 image-forensics-PG14.key - October 9, 2014

  • 32 image-forensics-PG14.key - October 9, 2014

  • 33 image-forensics-PG14.key - October 9, 2014

  • 34 image-forensics-PG14.key - October 9, 2014

  • 35 image-forensics-PG14.key - October 9, 2014

  • Light in front of camera

    Light behind camera

    36 image-forensics-PG14.key - October 9, 2014

  • 37 image-forensics-PG14.key - October 9, 2014

  • 38 image-forensics-PG14.key - October 9, 2014

  • 39 image-forensics-PG14.key - October 9, 2014

  • 40 image-forensics-PG14.key - October 9, 2014

  • Shading Constraints

    (c)(b)

    41 image-forensics-PG14.key - October 9, 2014

  • Shading Constraints

    8 a b

    c d

    d

    b

    c

    a 1 2

    3

    4

    5

    6 7

    8

    a b c d

    765

    4

    3 21

    a b c

    d

    1 2

    3

    4

    5

    6 7

    42 image-forensics-PG14.key - October 9, 2014

  • Shading Constraints

    8 a b

    c d

    d

    b

    c

    a 1 2

    3

    4

    5

    6 7

    8

    a b c d

    765

    4

    3 21

    a b c

    d

    1 2

    3

    4

    5

    6 7

    43 image-forensics-PG14.key - October 9, 2014

  • Shading Constraints

    c

    b

    a

    4

    3

    2 1

    b

    a

    c

    3

    2

    1

    4

    44 image-forensics-PG14.key - October 9, 2014

  • Motion in Video

    45-1 image-forensics-PG14.key - October 9, 2014

  • Motion in Video

    45-2 image-forensics-PG14.key - October 9, 2014

  • Parabolic Motion in World (Still Camera)

    c

    q⌧

    p⌧

    p⌧ = c+ ↵⌧ (q⌧ � c)

    ↵⌧

    ⌧ 2 1..n

    p⌧ = p0 +�t ⌧ v0 + 1

    2 (�t ⌧)2g

    Solve for: ↵⌧

    v0

    g

    46 image-forensics-PG14.key - October 9, 2014

  • Matching observed motion

    z

    x

    y

    47 image-forensics-PG14.key - October 9, 2014

  • http:// www.youtube.com/ watch?v=WbaH52JI3So

    48-1 image-forensics-PG14.key - October 9, 2014

  • http:// www.youtube.com/ watch?v=WbaH52JI3So

    48-2 image-forensics-PG14.key - October 9, 2014

  • 49-1 image-forensics-PG14.key - October 9, 2014

  • 49-2 image-forensics-PG14.key - October 9, 2014

  • z x

    y

    50-1 image-forensics-PG14.key - October 9, 2014

  • z x

    y

    50-2 image-forensics-PG14.key - October 9, 2014

  • c⌧

    q⌧

    p⌧

    Parabolic Motion in World (Moving Camera)

    p⌧ = c+ ↵⌧ (q⌧ � c) ⌧ 2 1..n

    p⌧ = p0 +�t ⌧ v0 + 1

    2 (�t ⌧)2g

    Solve for: ↵⌧

    v0

    g

    Track camera motion

    51 image-forensics-PG14.key - October 9, 2014

  • 52-1 image-forensics-PG14.key - October 9, 2014

  • 52-2 image-forensics-PG14.key - October 9, 2014

  • z

    x

    y

    53 image-forensics-PG14.key - October 9, 2014

  • Basic Mirror Geometry

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