Upgrade to Pro — share decks privately, control downloads, hide ads and more …

Suz Hinton on Accessible images (AIMS)

Suz Hinton on Accessible images (AIMS)

In my latest experimentations in 'Guerilla Accessibility,' I stumbled upon this paper a mere two weeks after publication and was excited about the explorations in it. The ideas built upon an unlikely hero of the anti-surveillance field delighted me. There are wide implementation gaps that remain unaddressed in this paper, and I took liberty on these when implementing the algorithms. I'll be sharing both the triumphs and pitfalls of this proposed technique of improving the accessibility of online web content.


February 15, 2018

More Decks by Papers_We_Love

Other Decks in Technology


  1. None
  2. a model to build self‐describing images for assisting screen reader

  3. Topics covered Web Accessibility Steganography techniques Browser Extensions

  4. Web Accessibility

  5. (A11y)

  6. Screen Readers

  7. Screen Readers JAWS NVDA VoiceOver Speakup TalkBack

  8. Demo

  9. <img src=“cat.jpg” alt=“grey cat asleep on a chair” />

  10. <img src=“decorative.jpg” alt=“” />

  11. Excerpt from Accessible images (AIMS): a model to build self‐describing

    images for assisting screen reader users
  12. Pros + Ease of implementation + Works with any image

    MIME type + Supported in browsers since HTML 2
  13. None
  14. Cons – Requires coding knowledge – Decoupled from the actual

    image – Plenty* of devs have little to no a11y skills *presenter’s observation of peers from over 12 years of experience in front-end development field
  15. None
  16. None
  17. May 16, 2006 newscientist.com/article/dn9177-gamers-help-the-blind-get-the-picture

  18. None
  19. Steganography

  20. Steganography the practice of concealing messages or information within other

    nonsecret text or data.
  21. None
  22. None
  23. None
  24. None
  25. there are many steganography techniques and approaches

  26. + concealing text in images + using LSB method

  27. 1 convert text to bits 2 store bits in LSBs

    of pixel data
  28. close up photo of a lion facing to the left

    99 1100011 ASCII character code
  29. 20, 255, 102 0010100 LSB c 99 1100011 ASCII character

    code save! 1
  30. None
  31. None
  32. None
  33. Assumptions ? knowing length of alt text ? method to

    compute bit position in image
  34. Knowing the length of alt text ? store length in

    consistent pixel location ? use special character to indicate end (EOF?) ? NLP (lol no)
  35. Computing bit position in image ? use a PRNG with

    seed ? decoder needs to know the seed
  36. Browser extension

  37. Browser extension third party script that can run on pages

    loaded by a user
  38. Browser extension a terrifying way to give third party code

    a same-origin policy waiver
  39. None
  40. None
  41. Implementation noopkat.github.io/a11y-alt-stego

  42. Pros + Description is portable with image + Less code

    + Less effort + Rad use of steganography
  43. Cons – Single language restriction – Lossless image format required

    – Compression can destroy / corrupt data – Most significant human labor not removed – Opt-in, standard adoption challenges
  44. thanks