The document discusses optimizing images for faster page loads and better user experience. It outlines four simple image optimizations: 1) reducing image quality to 85%, 2) using newer formats like WebP and SVG that compress smaller, 3) sizing images appropriately for different screen sizes through responsive images, and 4) lazy loading images below the fold. Implementing these optimizations across 500,000 mobile sites showed median savings of 2.83 seconds faster load time and 419KB less data. The document provides examples and tools to implement each optimization.

1. Delivering Beautiful and Fast Images
Doug Sillars
@DougSillars
PyConWeb
June 30, 2018

3. 0.5
0.6
0.7
0.8
0.9
Standing in Line Standing on the
edge of a virtual
cliff
Experiencing
Mobile Delays
Solving a Math
Problem
https://www.ericsson.com/res/docs/2016/mobility-report/emr-feb-2016-the-stress-of-steaming-delays.pdf
Stress

4. Large Downloads Induce Delays in Rendering
3s: 53% of Users Abandon Mobile Sites
500ms: 26% Frustration
8% Engagement
100ms: 1% Revenue Walmart & Amazon (Desktop 2001)
4% Mobile Users Throw Their Phones
https://www.doubleclickbygoogle.com/articles/mobile-speed-matters
http://bit.ly/mobileWebStress
http://www.globaldots.com/how-website-speed-affects-conversion-rates/
https://www.mobilejoomla.com/blog/172-responsive-design-vs-server-side-solutions-infographic.html

5. Images make up 50% of Web Content
HTTPArchive mobile websites 15/02/18

6. Image Performance Analysis
https://Webpagetest.org https://httparchive.org

7. 4 Simple Image Optimizations

8. 4 Simple Image Optimizations
1. Quality
2. Format
3. Sizing
4. Lazy Loading

9. 4 Simple Image Optimizations
1. Quality
2. Format
3. Sizing
4. Lazy Loading

10. 4 Simple Image Optimizations
1. Quality
2. Format
3. Sizing
4. Lazy Loading

11. Image Quality
Lossy
Image size is reduced by
removing pixel information
https://developers.google.com/speed/docs/insights/OptimizeImages

12. Image Quality
magick -quality 85 riga.jpg riga85.jpg
http://res.cloudinary.com/dougsillars/image/upload/q_85/v1520504964/IMG_20180301_114117_tzasan.jpg
Lighthouse:
Recommends 85% quality on all images
https://developers.google.com/speed/docs/insights/OptimizeImages

13. Image Quality Use “In The Wild”
500,000 mobile sites
Analyzed 3/15/18

14. Image Quality Use “In The Wild”
Median Savings (50th percentile):
• 2.83 seconds faster page load
• 419KB less data

15. 100%
2.0 MB
https://res.cloudinary.com/dougsillars/image/upload/v1530340569/IMG_20151012_130742671_fafhpu.jpg

16. 85%
1.31 MB
q_85
https://res.cloudinary.com/dougsillars/image/upload/q_85/v1530340569/IMG_20151012_130742671_fafhpu.jpg

17. 50%
611 KB
q_50
https://res.cloudinary.com/dougsillars/image/upload/q_50/v1530340569/IMG_20151012_130742671_fafhpu.jpg

18. 20%
314 KB
q_20
https://res.cloudinary.com/dougsillars/image/upload/q_20/v1530340569/IMG_20151012_130742671_fafhpu.jpg

19. Graphing the Results
https://developers.google.com/speed/docs/insights/OptimizeImages

20. Graphing the Results
https://developers.google.com/speed/docs/insights/OptimizeImages

21. Automate Quality vs. File Size
• Butteraugli
• SSIM: Structural SIMilarity
https://github.com/technopagan/cjpeg-dssim
cjpeg-dssim jpegoptim munich.jpg
http://res.cloudinary.com/dougsillars/image/upload/q_auto/v1529005982/IMG_20180614_184507_ssuk1i.jpg

22. SSIM
1.07 MB
https://res.cloudinary.com/dougsillars/image/upload/q_auto/v1530340569/IMG_20151012_130742671_fafhpu.jpg

23. Graphing the Results
https://developers.google.com/speed/docs/insights/OptimizeImages

24. Results:
• Test Load on Motorola G4:

25. 4 Simple Image Optimizations
1. Quality
2. Format
3. Sizing
4. Lazy Loading

26. Image Formats – Average Size
HTTPArchive mobile websites 15/02/18

27. Image Formats – Average Size
HTTPArchive mobile websites 15/02/18

28. Scalable Vector Graphics (SVG)
Images drawn as shapes
infinitely scalable
XML - Can be added inline to HTML document
https://gist.github.com/hail2u/2884613?short_path=66a60ff

29. Scalable Vector Graphics (SVG)
Images drawn as shapes
infinitely scalable
XML - Can be added inline to HTML document
https://gist.github.com/hail2u/2884613?short_path=66a60ff

30. Scalable Vector Graphics (SVG)
Images drawn as shapes
infinitely scalable
XML - Can be added inline to HTML document
https://gist.github.com/hail2u/2884613?short_path=66a60ff

31. Scalable Vector Graphics (SVG)

32. Scalable Vector Graphics (SVG)

33. Scalable Vector Graphics (SVG)
https://github.com/google/brotli

34. Image Formats – Average Size
HTTPArchive mobile websites 15/02/18

35. SSIM + WebP
911 KB
https://res.cloudinary.com/dougsillars/image/upload/q_auto,f_auto/v1530340569/IMG_20151012_130742671_fafhpu.jpg

36. File Format: Web
<picture>
<source width = "100%" type="image/webp" srcset=”riga.webp">
<img width = "100%" src=”riga_cjpeg_dssim.jpg"
alt=”Riga, Latvia">
</picture>
<img
src=‘http://res.cloudinary.com/dougsillars/image/upload/q_auto,f_auto/v1529005982/IMG_20180614_184507_ssuk1i.jpg’>

37. File Format: WebP
https://caniuse.com/#feat=webp

38. Image Format Use “In The Wild”
500,000 mobile sites
Analyzed 3/15/18

39. Image Format Use “In The Wild”
500,000 mobile sites
Analyzed 3/15/18

40. 4 Simple Image Optimizations
1. Quality
2. Format
3. Sizing
4. Lazy Loading

41. Image Sizing
-

42. Image Sizing

43. Image Sizing
-

44. Image Sizing
624
832
-

45. Image Sizing
624
832
12,979,000 pixels
519,000 pixels
_________________
-
12,460,000 pixels

46. Image Sizing
624
832
12,979,000 pixels
519,000 pixels
_________________
-
12,460,000 pixels

47. Image Sizing
https://twitter.com/paulcalvano/status/928751141843808256

48. Image Sizing
-
Responsive Images:
Generate a set of images
25 KB difference in size

49. Responsive Images
624
832
625,000 pixels
-
106,000 pixels
519,000 pixels
_________________

50. Responsive Breakpoint Generation
https://github.com/cloudinary/responsive_breakpoints_generator
http://www.responsivebreakpoints.com/

51. Responsive Images

52. Responsive Images

53. Responsive Images

54. Responsive Images
+
Image Format
Create responsive WebP
mogrify -format webp *.jpg

55. Responsive Images + Client Hints

56. Responsive Images + Client Hints

57. Responsive Images Use “In The Wild”
500,000 mobile sites
Analyzed 3/15/18

58. Responsive Images Use “In The Wild”
442,000 mobile sites
Analyzed 3/15/18

59. Sample Website

60. Sample Website

61. 4 Simple Image Optimizations
1. Quality
2. Format
3. Sizing
4. Lazy Loading

62. Web Usage
https://www.nngroup.com/articles/scrolling-and-attention/
https://calendar.perfplanet.com/2017/progressive-image-loading-using-intersection-observer-and-sqip/

63. Web Usage
https://www.nngroup.com/articles/scrolling-and-attention/
https://calendar.perfplanet.com/2017/progressive-image-loading-using-intersection-observer-and-sqip/

64. Lazy Loading
https://www.nngroup.com/articles/scrolling-and-attention/
https://calendar.perfplanet.com/2017/progressive-image-loading-using-intersection-observer-and-sqip/

65. Lazy Loading Use “In The Wild”
442,000 mobile sites
Analyzed 3/15/18

66. Lazy Loading Use “In The Wild”
442,000 mobile sites
Analyzed 3/15/18

67. Lazy Loading
https://www.nngroup.com/articles/scrolling-and-attention/
https://calendar.perfplanet.com/2017/progressive-image-loading-using-intersection-observer-and-sqip/

68. Preview Images

69. Optimizing Content Delivery
Preview Images
https://github.com/technopagan/sqip

70. Preview Images

71. 4 Simple Image Optimizations
1. Quality
2. Format
3. Sizing
4. Lazy Loading

72. Image Optimizations – 500k sites
100 score for:
1. Quality
2. Format
3. Sizing
4. Lazy Loading

73. Image Optimizations – 500k sites
100 score for:
1. Quality
2. Format
3. Sizing
4. Lazy Loading

74. Image Optimizations – 500k sites
100 score for:
1. Quality
2. Format
3. Sizing
4. Lazy Loading

75. Image Optimizations – 500k sites
100 score for:
1. Quality
2. Format
3. Sizing
4. Lazy Loading

76. Image Optimizations – 500k sites
100 score for:
1. Quality
2. Format
3. Sizing
4. Lazy Loading

77. Summary
Testing:
WebPageTest https://www.webpagetest.org
HttpArchive https://httparchive.org
Images:
ImageMagick https://www.imagemagick.org
SSIM https://github.com/technopagan/cjpeg-dssim
LazySizes https://github.com/aFarkas/lazysizes
Responsive Breakpoints http://www.responsivebreakpoints.com/
Cloudinary https://www.cloudinary.com
Tooling

78. Conclusion
Images and Video
can be Beautiful AND Fast

79. Animated GIFs
Original MP4
1.4 MB

80. Animated GIFs

81. Animated GIFs
Animated GIF
3.8 MB
270% larger

82. Animated GIFs

83. Animated GIFs
MP4: 256 colors
247KB
93% smaller

84. Animated GIFs
Video Tags:
<video loop autoplay muted playsinline controls = "false” src="goats.mp4”/>
Video is not pre-loaded, will be last to download
Img tags are fast!
<picture>
<source type="video/mp4" srcset=”goats.mp4">
<source type="image/webp" srcset=”goats.webp">
<img src=”goats.gif">
</picture>
https://calendar.perfplanet.com/2017/animated-gif-without-the-gif/

85. Animated GIFs