Improving performance with responsive (and responsible!) images [OpenWest]

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David Newton, St. Michael’s Hospital 1 Improving performance with responsive (and responsible!) images OpenWest, 2015-05-07 Twitter: @newtron Github: @nwtn Email: david@davidnewton.ca Slides: https://github.com/nwtn/pres-respimg-perf-openwest

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2 Web performance

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“ 3 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)

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“ 4 Good performance is good design. —Brad Frost

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5 Why images?

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6 —Marc Andreessen, www-talk, February 1993

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“ 8 More human beings today have access to a cellphone than…a clean toilet. –Anand Giridharadas, New York Times April 10 2010

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“ 8 More human beings today have access to a cellphone than…a clean toilet. –Anand Giridharadas, New York Times April 10 2010

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9 — OpenSignal, Android Fragmentation Visualized (August 2014)

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10 —https://twitter.com/lukew/status/507880029737328640/photo/1

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11 img { max-width: 100%; }

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14 A solution: Serve one big image and let the browser scale it

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19 Bullet 1 Bullet 2 Bullet 3

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20 Bullet 1 Bullet 2 Bullet 3

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22 2x resolution = 4x as many pixels 3x resolution = 9x as many pixels 4x resolution = 16x as many pixels

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23 more pixels = more energy more pixels = more money more pixels = more time

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24 — Dave Rupert , Mo’ Pixels, Mo’ Problems Caption

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25 That’s why images.

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26 Responsive images

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27 A solution: Serve one big image and let the browser scale it

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28 A better solution: Serve an appropriate image to each user

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32 SVG WebP JPEG XR JPEG 2000

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34 Using JavaScript is a bad idea.

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35 Using CSS is a bad idea.

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36 http://whatwg.org/html#the-picture-element Responsive images speciﬁcation

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37 You can use this now!

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38 Firefox (Gecko) Chrome/Opera (Blink) Safari (WebKit) Internet Explorer/ Edge srcset + sizes Works now! Firefox 38 Works now! Chrome 34 Opera 21 Works now! * Safari 6.2 Safari 7.1 iOS 8 In development picture Works now! Firefox 38 Works now! Chrome 38 Opera 25 In development Under consideration

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39 http://picturefill.responsiveimages.org/ Picturefill by Scott Jehl & others http://filamentgroup.com/lab/to-picturefill.html To Picturefill, or not to Picturefill

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40 Resolution switching Markup

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40 Resolution switching Markup

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48 Viewport (and resolution!) switching Markup

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62 File type switching Markup

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70 Art direction Markup

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71 —Adventure Time

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80 All the things! Markup a.k.a. the scary slide

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80 All the things! Markup a.k.a. the scary slide

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83 http://whatwg.org/html#the-picture-element Responsive images speciﬁcation

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84 Responsive images are a pain in the butt

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86 https://www.npmjs.com/package/grunt-respimg grunt-respimg

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87 $ npm install grunt-respimg --save-dev

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88 https://www.npmjs.com/package/grunt- responsive-images-extender/ grunt-responsive-images-extender

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89 $ npm install grunt-responsive-images- extender --save-dev

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90 https://github.com/nwtn/php-respimg/ php-respimg

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91 $ composer require nwtn/php-respimg

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92 https://wordpress.org/plugins/ricg- responsive-images/ WP RICG Responsive Images plugin

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93 Responsible images

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94 1. Responsive images

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95 1. Responsive images 2. Image optimization

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96 https://imageoptim.com/ ImageOptim https://github.com/toy/image_optim image_optim https://github.com/svg/svgo-gui SVGO-GUI https://github.com/svg/svgo SVGO

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97 SetOutputFilter DEFLATE AddOutputFilterByType DEFLATE "image/svg+xml"

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98 1. Responsive images 2. Image optimization 3. Deferred image loading

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100

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101 http://css-tricks.com/snippets/javascript/lazy-loading-images/ LazyLoad JS scripts and plugins, e.g.:

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102 1. Responsive images 2. Image optimization 3. Deferred image loading 4. CDNs & Caching

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103 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"

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104 1. Responsive images 2. Image optimization 3. Deferred image loading 4. CDNs & Caching 5. Appropriate contrast and colour

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105 7% 8% 10% 11% 29% 35% April May June July August September

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106 7% 8% 10% 11% 29% 35% April May June July August September

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107

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108 http://colororacle.org/ Color Oracle

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109 September 7% August 8% July 10% June 11% May 29% April 35%

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110 1. Responsive images 2. Image optimization 3. Deferred image loading 4. CDNs & Caching 5. Appropriate contrast and colour 6. Text-based alternatives

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111 [alt] [aria-describedby], [aria-labelledby] [longdesc] SVG elements and attributes

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112 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

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113 1. Responsive images 2. Image optimization 3. Deferred image loading 4. CDNs & Caching 5. Appropriate contrast and colour 6. Text-based alternatives 7. Fewer images!

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114 Performance impact

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117 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)

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118 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)

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119

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120 Accessibility Progressive enhancement Responsive web design Web performance

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David Newton, St. Michael’s Hospital 121 Improving performance with responsive (and responsible!) images OpenWest, 2015-05-07 Twitter: @newtron Github: @nwtn Email: david@davidnewton.ca Slides: https://github.com/nwtn/pres-respimg-perf-openwest