Using Responsive Images Responsibly: Performance & Accessibility

C3e8ba214714b1402f3073334249fcdc?s=47 newtron
September 27, 2014

Using Responsive Images Responsibly: Performance & Accessibility

Accessibility Camp Toronto 2014,
September 27, 2014
https://github.com/nwtn/pres-respimg-perf-a11yto

C3e8ba214714b1402f3073334249fcdc?s=128

newtron

September 27, 2014
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  1. 1.

    David Newton, St. Michael’s Hospital 1 Using Responsive Images Responsibly:

    Performance & Accessibility: Accessibility Camp Toronto 2014 Twitter:!@newtron! Github:!@nwtn! Email:!! david@davidnewton.ca! ! Slides:! https://github.com/nwtn/pres-respimg-perf-a11yto
  2. 4.

    “ 4 ‘Disability’ means… any degree of physical disability, infirmity,

    malformation or disfigurement that is caused by bodily injury, birth defect or illness… —Accessibility for Ontarians with Disabilities Act
  3. 6.

    “ 6 Following these guidelines will make content accessible to

    a wider range of people with disabilities, including blindness and low vision, deafness and hearing loss, learning disabilities, cognitive limitations, limited movement, speech disabilities, photosensitivity and combinations of these. Following these guidelines will also often make your Web content more usable to users in general. —Web Content Accessibility Guidelines 2.0! (emphasis mine)
  4. 8.

    “ 8 The goal of Web design is not merely

    to dazzle, but to deliver information to the widest audience possible.! ! …Compromise should not come at the expense of the user, but rather in terms of the native capabilities of the user’s choice of device.…! ! Leave no one behind. —Steven Champeon, Inclusive Web Design for the Future! (emphasis mine)
  5. 9.
  6. 11.

    “ 11 Rather than creating disconnected designs, each tailored to

    a particular device or browser, we should instead treat them as facets of the same experience. —Ethan Marcotte, Responsive Web Design! (emphasis mine)
  7. 12.

    12 Responsive web design Deliver a great experience to all

    users, regardless of their viewing context.
  8. 14.

    “ 14 Many of us are fortunate to live in

    high bandwidth regions, but there are still large portions of the world that do not. By keeping your client side code small and lightweight, you can literally open your product up to new markets. —Chris Zacharias, Page Weight Matters! (emphasis mine)
  9. 19.

    18 Accessibility Progressive enhancement Responsive web design Web performance Universal

    web design Accessibility Progressive enhancement Responsive web design Web performance
  10. 20.

    18 Accessibility Progressive enhancement Responsive web design Web performance Universal

    web design Accessibility Progressive enhancement Responsive web design Web performance
  11. 22.

    “ 19 Universal design is the design of products and

    environments to be usable by all people, to the greatest extent possible, without the need for adaptation or specialized design. —Ronald L. Mace
  12. 24.

    21 63% of Americans used a phone to access the

    internet! 34% of Americans used a mobile device as their primary way to access the web
  13. 25.

    “ 22 More human beings today have access to a

    cellphone than…a clean toilet. –Anand Giridharadas, New York Times April 10 2010
  14. 26.

    “ 22 More human beings today have access to a

    cellphone than…a clean toilet. –Anand Giridharadas, New York Times April 10 2010
  15. 30.

    26

  16. 31.

    27

  17. 33.

    29

  18. 34.

    30

  19. 35.

    31 —HTTP Archive, September 15 2014 Stylesheets 56 KB HTML

    59 KB Flash 75 KB Other 141 KB Scripts 296 KB Images 1,194 KB Total 1,890 KB
  20. 36.

    32

  21. 37.

    33 2x resolution = 4x as many pixels! 3x resolution

    = 9x as many pixels! 4x resolution = 16x as many pixels
  22. 38.

    34 more pixels = more energy! more pixels = more

    money! more pixels = more time
  23. 44.

    40

  24. 45.

    41

  25. 46.

    42

  26. 48.

    44

  27. 52.

    48 Firefox! (Gecko) Chrome/Opera! (Blink) Safari! (WebKit) Internet Explorer! (Trident)

    srcset (partial) N/A Chrome 34! Opera 21 Safari 8 N/A? srcset (full)! +! sizes Behind a flag: FF 32! On by default: FF 36? Behind a flag: C37, O24! On by default: C38, O25 Safari 8.1? 12? picture Behind a flag: FF 33! On by default: FF 36? Behind a flag: C37, O24! On by default: C38, O25 Safari 8.1? 12?
  28. 57.
  29. 58.
  30. 59.
  31. 60.
  32. 61.

    56 <img src="wolf600.jpg" alt="A rad wolf" srcset="wolf300.jpg 0.5x, wolf600.jpg 1x,

    wolf1200.jpg 2x, wolf2400.jpg 3x, wolf4800.jpg 4x" />
  33. 62.

    57 <img src="wolf600.jpg" alt="A rad wolf" srcset="wolf300.jpg 0.5x, wolf600.jpg 1x,

    wolf1200.jpg 2x, wolf2400.jpg 3x, wolf4800.jpg 4x" />
  34. 65.

    60 <img src="wolf4800.jpg" alt="A rad wolf" sizes="100vw" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  35. 66.

    61 <img src="wolf4800.jpg" alt="A rad wolf" sizes="100vw" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  36. 67.

    62 <img src="wolf4800.jpg" alt="A rad wolf" sizes="100vw" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  37. 68.

    63 <img src="wolf4800.jpg" alt="A rad wolf" sizes="100vw" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  38. 69.

    64 <img src="wolf4800.jpg" alt="A rad wolf" sizes="100vw" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  39. 70.

    65 <img src="wolf4800.jpg" alt="A rad wolf" sizes="100vw" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  40. 71.

    66 <img src="wolf4800.jpg" alt="A rad wolf" sizes="600px" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  41. 72.

    67 <img src="wolf4800.jpg" alt="A rad wolf" sizes="calc(100vw - 10em)" srcset="wolf300.jpg

    300w, wolf600.jpg 600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  42. 73.

    68 <img src="wolf4800.jpg" alt="A rad wolf" sizes=“100%" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  43. 74.

    69 <img src="wolf4800.jpg" alt="A rad wolf" sizes="100vw" srcset="wolf300.jpg 300w, wolf600.jpg

    600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  44. 75.

    70

  45. 76.

    71 <img src="wolf4800.jpg" alt="A rad wolf" sizes="(min-width: 1000px) 33vw, (min-width:

    600px) 50vw, 100vw" srcset="wolf300.jpg 300w, wolf600.jpg 600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  46. 77.

    72 <img src="wolf4800.jpg" alt="A rad wolf" sizes="(min-width: 1000px) 33vw, (min-width:

    600px) 50vw, 100vw" srcset="wolf300.jpg 300w, wolf600.jpg 600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  47. 88.

    83

  48. 89.

    84

  49. 91.

    86 <picture> <source media="(min-width: 1000px)" srcset="wolf-crop-bg.jpg" /> <source media="(min-width: 600px)"

    srcset="wolf-crop-sm.jpg" /> <img src="wolf.jpg" alt="A rad wolf" /> </picture>
  50. 92.

    87 <picture> <source media="(min-width: 1000px)" srcset="wolf-crop-bg.jpg" /> <source media="(min-width: 600px)"

    srcset="wolf-crop-sm.jpg" /> <img src="wolf.jpg" alt="A rad wolf" /> </picture>
  51. 93.

    88 <picture> <source media="(min-width: 1000px)" srcset="wolf-crop-bg.jpg" /> <source media="(min-width: 600px)"

    srcset="wolf-crop-sm.jpg" /> <img src="wolf.jpg" alt="A rad wolf" /> </picture>
  52. 94.

    89 <picture> <source media="(min-width: 1000px)" srcset="wolf-crop-bg.jpg" /> <source media="(min-width: 600px)"

    srcset="wolf-crop-sm.jpg" /> <img src="wolf.jpg" alt="A rad wolf" /> </picture>
  53. 95.

    90 <picture> <source media="(min-width: 1000px)" srcset="wolf-crop-bg.jpg" /> <source media="(min-width: 600px)"

    srcset="wolf-crop-sm.jpg" /> <img src="wolf.jpg" alt="A rad wolf" /> </picture>
  54. 98.

    92 <picture> <source type="image/webp" media="(min-width: 1000px)" sizes="33vw" srcset="wolf-crop-big-300.jpg 300w, wolf-crop-big-600.jpg

    600w, wolf-crop-big-1200.jpg 1200w, wolf-crop-big-2400.jpg 2400w, wolf-crop-big-4800.jpg 4800w" /> <source type="image/webp" media="(min-width: 600px)" sizes="50vw" srcset="wolf-crop-small-300.jpg 300w, wolf-crop-small-600.jpg 600w, wolf-crop-small-1200.jpg 1200w, wolf-crop-small-2400.jpg 2400w, wolf-crop-small-4800.jpg 4800w" /> <source type="image/webp" sizes="100vw" srcset="wolf-crop-med-300.jpg 300w, wolf-crop-med-600.jpg 600w, wolf-crop-med-1200.jpg 1200w, wolf-crop-med-2400.jpg 2400w, wolf-crop-med-4800.jpg 4800w" /> <source media="(min-width: 1000px)" sizes="33vw" srcset="wolf-crop-big-300.jpg 300w, wolf-crop-big-600.jpg 600w, wolf-crop-big-1200.jpg 1200w, wolf-crop-big-2400.jpg 2400w, wolf-crop-big-4800.jpg 4800w" /> <source media="(min-width: 600px)" sizes="50vw" srcset="wolf-crop-small-300.jpg 300w, wolf-crop-small-600.jpg 600w, wolf-crop-small-1200.jpg 1200w, wolf-crop-small-2400.jpg 2400w, wolf-crop-small-4800.jpg 4800w" /> <source sizes="100vw" srcset="wolf-crop-med-300.jpg 300w, wolf-crop-med-600.jpg 600w, wolf-crop-med-1200.jpg 1200w, wolf-crop-med-2400.jpg 2400w, wolf-crop-med-4800.jpg 4800w" /> <img src="wolf-crop-med-600.jpg" alt="A rad wolf" /> </picture> !
  55. 99.

    93 <img src="wolf600.jpg" alt="A rad wolf" sizes="(min-width: 1000px) 33vw, (min-width:

    600px) 50vw, 100vw" srcset="wolf300.jpg 300w, wolf600.jpg 600w, wolf1200.jpg 1200w, wolf2400.jpg 2400w, wolf4800.jpg 4800w" />
  56. 107.

    101

  57. 108.

    102

  58. 112.

    106 ExpiresActive on ExpiresDefault "access plus 1 month" ExpiresByType image/gif

    "access plus 1 year" ExpiresByType image/jpeg "access plus 1 year" ExpiresByType image/png "access plus 1 year" ExpiresByType image/svg+xml "access plus 1 year" Note: Apache is confusing and I’m not guaranteeing this will work.
  59. 113.

    107 1. Responsive images! 2. Image optimization! 3. Deferred image

    loading! 4. Caching & CDNs! 5. Appropriate contrast and colour! !
  60. 114.
  61. 115.
  62. 116.

    110

  63. 119.

    113 1. Responsive images! 2. Image optimization! 3. Deferred image

    loading! 4. Caching & CDNs! 5. Appropriate contrast and colour! 6. Text-based alternatives!
  64. 121.

    115 http://www.w3.org/TR/html-alt-techniques/ HTML5: Techniques for providing useful text alternatives http://www.w3.org/WAI/GL/wiki/Using_aria-describedby_to_provide_descriptions_of_images

    Using aria-describedby to provide descriptions of images http://w3c.github.io/test-results/html-longdesc/cr-report.html longdesc Implementation Report http://www.paciellogroup.com/blog/2013/12/using-aria-enhance-svg-accessibility/ Using ARIA to enhance SVG accessibility http://www.w3.org/WAI/GL/wiki/Using_aria-labelledby_to_provide_a_text_alternative_for_non- text_content Using aria-labelledby to provide a text alternative for non-text content
  65. 122.

    116 1. Responsive images! 2. Image optimization! 3. Deferred image

    loading! 4. Caching & CDNs! 5. Appropriate contrast and colour! 6. Text-based alternatives! 7. Fewer images!
  66. 124.

    118

  67. 125.

    119

  68. 126.

    120 Unoptimized Optimized + Responsive Optimized + Responsive + Lazyload

    CSS 1 KB 1 KB 1 KB HTML 2 KB 3 KB 3 KB Scripts 29 KB 33 KB 33 KB Images 661 KB 253 KB 87 KB Total 693 KB 290 KB! (~58% savings) 119 KB! (~83% savings)
  69. 127.

    121 Browser Unoptimized Optimized + Responsive + Lazyload Firefox (Desktop)

    2.2 s 2.0 s Safari (iOS) 2.1 s 1.7 s Average 2.2 s 1.9 s! (~14% savings)
  70. 128.

    122

  71. 130.

    David Newton, St. Michael’s Hospital 124 Using Responsive Images Responsibly:

    Performance & Accessibility: Accessibility Camp Toronto 2014 Twitter:!@newtron! Github:!@nwtn! Email:!! david@davidnewton.ca! ! Slides:! https://github.com/nwtn/pres-respimg-perf-a11yto