1. PBA Front-End Week 3

2. Colors, theory & practice Why are colors important…?

3. Colors, theory & practice Vision is (usually) the ”strongest” human sense – primary source of information Humans are good at spotting differences in colors (~10 million hues) Colors and feelings are closely related On a website, colors is the first thing we notice – first impression is important!

4. Colors, theory & practice What are colors actually? Physically: Electro- magnetic radiation in a narrow wavelength interval Actual colors exist only in our brains…

5. Colors, theory & practice Primary colors: – Yellow – Blue – Red

6. Colors, theory & practice Secondary colors: – Green – Orange – Violet

7. Colors, theory & practice Tertiary colors: – Yellow-orange – Red-orange – Red-violet – Blue-violet – Blue-green – Yellow-green

8. Colors, theory & practice Complimentary colors: Colors opposite each other on the color wheel

9. Colors, theory & practice Analogous colors: Colors next to each other on the color wheel

10. Colors, theory & practice Warm colors Cool colors

11. Colors, theory & practice Tint – adding white to a pure color

12. Colors, theory & practice Shade – adding black to a pure color

13. Colors, theory & practice Tone – adding grey to a pure color

14. Colors, theory & practice How do we define a color in quantitative terms (using numbers) We use color models Most widespread color model in the context of computers is RGB Additive color model, uses Red, Green and Blue as additive primary colors (why not Yellow instead of Green…?)

15. Colors, theory & practice Typical representation in RGB is to use 24 bits 24 bits = 3 bytes One byte for each component color Approx 16.7 millions hues possible Approx what the human eye/brain can differentiate www.colorpicker.com

16. Colors, theory & practice How are colors relevant with regards to Web Design? Usability: Good color choices make the website easier to use (to read, to navigate,…) Convey emotions: Colors are strongly associated with human emotions

17. Colors, theory & practice How does color affect usability Text: If a website is text-rich, colors should ”support” the user in reading text Avoid choices that make it hard to read the text; the user will tire and go away…

18. Colors, theory & practice These are (almost) complimentary colors… You could then assume that they would produce high contrast…..and make the text easy to read… …but it doesn’t look like it!

19. Colors, theory & practice Black and white is often a good choice for text Can appear somewhat ”harsh” on the eye Can be softened with e.g. beige background, grey text

20. Colors, theory & practice Black and white is often a good choice for text Can appear somewhat ”harsh” on the eye Can be softened with e.g. beige background, grey text

21. Colors, theory & practice Black and white is often a good choice for text Can appear somewhat ”harsh” on the eye Can be softened with e.g. beige background, grey text …And even in reverse, maybe…

22. Colors, theory & practice Also, colors should not surprise the user On a website, I expect that this is a link ”Wrong” colors may also confuse a user who must make a choice: Do you really wish to delete your user profile? YesNo

23. Colors, theory & practice Fact: Colors invoke feelings! Why…? Which feelings? Depends on – Culture – Personality – Mood – …?

24. Colors, theory & practice

29. You can find more color symbolisms at: http://webdesign.about.com/od/colorcharts/l/bl_colorculture.htm http://webdesign.about.com/od/colorcharts/l/bl_colorculture.htm You can probably find other interpretations elsewhere as well…

30. Colors, theory & practice Now I have to design a website, including choosing colors…how do I start? In many situations, the colors for the website may be predetermined Visual corporate identity

31. Colors, theory & practice

33. The obvious colors might also be ”taken” by somebody or something you do not want to be associated with…

34. Colors, theory & practice If choice of colors is ”free”… …start by finding adjectives that match the theme of your website Find base color(s) that match those adjectives (not more than three colors) Decide what kind of color scheme you will apply

35. Colors, theory & practice Color scheme – a palette of colors to apply to your wesbite Given the base color(s), find additional colors to apply A number of standard color harmonies exist for generating color schemes

36. Colors, theory & practice (taken from www.tigercolor.com )www.tigercolor.com

37. Colors, theory & practice (taken from www.tigercolor.com )www.tigercolor.com

38. Colors, theory & practice (taken from www.tigercolor.com )www.tigercolor.com

39. Colors, theory & practice (taken from www.tigercolor.com )www.tigercolor.com

40. Colors, theory & practice (taken from www.tigercolor.com )www.tigercolor.com

41. Colors, theory & practice (taken from www.tigercolor.com )www.tigercolor.com

42. Colors, theory & practice

44. Visual elements Why do we actually need graphics on a website…?

45. Visual elements Just as for colors, a distinct graphic can be part of a corporate identity In general, we use graphics for – Illustration – Explanation – Integration

46. Visual elements ”Many children on the African continent suffer from malnutrition, which can be attributed to poor living conditions, climate changes, civil unrest and population growth”

47. Visual elements

48. ”Many people find that Puppies are cute, and the prominent eyes, fluffy fur and their childish personalities and behavior support this percep- tion of Puppies”

49. Visual elements

50. An illustration can – obviously – convey emotions very effectively Illustrations should of course be chosen in accordance with the general theme, style and tone of the website DNA…?

51. Visual elements A diagram can help explain complex concepts to the user However, the complexity of the diagram need not be reduced (no dumbing-down…) Be aware of physical limitations – Printed material: 300+ dpi (dots per inch) – PC Screen resolution: 80-100 dpi

52. Visual elements A chart can help present quantita- tive data to the user Same considerations as for diagrams apply to charts

53. Visual elements General tips on using diagrams/charts: – Trust the reader’s intelligence – Respect the medium – Tell the truth as you see it – Do not bias your data – Be bold and substantial …and test it!

54. Visual elements Still quite a number of technical issues to consider when using graphics – Display capacity – Bandwith – File formats – Graphics technology – Graphics compression

55. Visual elements Mainstream PC monitor anno 2011 – 24” size, 16:9 format (approx 20” x 12”) – 1920x1080 resolution – Approx 100 dpi – 24-bit color (16.7 mill hues) – Price: Cheap!

56. Visual elements Other displays – Laptop: 12”-17”, around 120 dpi – Tablet: 7”-10”, around 150 dpi (iPad 132) – SmartPhones: 3”-5”, up to 300 dpi (!) Upcoming resolutions – 2560x1600 (even in 10” tablets!) – QFHD/4K, about 10M pixels (later…)

57. Visual elements No reason to rework e.g. a printed image with regards to colors – we can show all colors! May need to rework resolution Graphics for the web should be optimised for typical screen resolutions – current recommen- dation is 72 dpi (ppi)

58. Visual elements Gamma – degree of midtone contrast (?)

59. Visual elements What can we assume about bandwidth…? Does ”eyerybody” have a broadband (2+ mbps) connection now…? What about mobile broadband…? Is the ”penetration” of high-speed access related to e.g. demographic factors?

60. Visual elements

63. The more graphics on a web page, the longer it takes to load (duh!?) BUT – 0,01 sec vs. 0,1 sec, not so important – 1 sec vs. 10 secs, definitely important!

64. Visual elements Even with broadband, care must be taken to optimise physical size of graphics Efficient algorithms for compressing images exist – images can thus be stored as: – Uncompressed – Compressed without quality loss – Compressed with quality loss Pixel-oriented graphics are called raster graphics

65. Visual elements Uncompressed – Saved as ”raw” bitmap – Fixed number of bits per pixel (4-24) – Size only depends on image size –.bmp format (on Windows) – Should never be used on the Web!

66. Visual elements Compressed without loss of quality – Several different algorithms (e.g. Lempel-Ziv- Welch, or just LZW) – Used in the GIF image format (and PNG) – GIF only supports 256 colors in an image, but the actual 256 colors can vary – GIF suitable for sharp-edge line art (logo), simple animations, low-res clips (animated GIF) – Not so well suited for high-quality images

67. Visual elements Good for GIF Not-so-good for GIF

68. Visual elements Compressed with (possible) loss of quality – Most common file format is JPEG – Offers image quality vs. file size tradeoff – Compression highly dependent on image content and complexity, can be quite impressive – Can be used for….anything. But where is a non- perfect image acceptable? Logo, probably not Photo, probably ok

69. Visual elements http://en.wikipedia.org/wiki/File:Quality_com parison_jpg_vs_saveforweb.jpg http://en.wikipedia.org/wiki/File:Quality_com parison_jpg_vs_saveforweb.jpg

70. Visual elements Progressive JPEG – Loads successively better versions of the image – Useful for providing ”preview” of a large image – Helps on user impatience – NOTE: Not fully supported by all browsers

71. Visual elements Be aware that JPEG is a no-way-back compression of images! Keep the original material uncompressed, and create suitably compressed JPEG versions as needed

72. Visual elements Small graphics for navigation, buttons, logos, simple icons, etc Sharp-edge line art, e.g. diagrams Use GIF/PNG Small-to-medium images (up to about 200x200) Use GIF/PNG or JPEG, not much difference in file size Large imagesUse JPEG

73. Visual elements Vector graphics Defining an image in terms of geometric shapes instead of pixels No inherent resolution! Image definition is purely logical (geometric)

74. Visual elements Creating vector graphics – Mostly useful for creating complex diagrams, illustrations, etc. – Several professional programs for creating vector graphics exist (Abode Illustrator) – Most common file format is SVG (Scalable Vector Graphics), developed by W3C

75. Visual elements Using vector graphics – Can be converted to e.g. JPEG in any desired quality, and then published – Adobe Flash supports vector graphics directly – Some browsers support SVG, but not all – Recommendation: Create source material as vector graphics, publish on the Web as raster graphics

76. Visual elements Using video on a Website…why? – Some concepts lend themselves well to ”dynamic” visual presen- tation (complex instructions, sales presentations, etc.) – Users are used to video on the Web (Youtube) – Bandwidth is not really an issue anymore

77. Visual elements Using video on a Website…why not? – Producing high-quality video is very costly and time-demanding – Users have higher and higher expectations concerning quality of content – Bandwidth is still an issue

78. Visual elements Video uses a lot of bandwidth! Almost all video formats use some sort of compression Other factors – Resolution – Frame rate – Content http://web.forret.com/tools/video_fps.asp

79. Visual elements Examples of video bit rates (MPEG2) – Blu-Ray: 40 Mbit – 1080i: 25 Mbit – 720p: 18 Mbit – DVD: 10 Mbit – Standard TV, 576i: 3-4Mbit – 320x240: 0,5 Mbit BUT, can be reduced with quality loss

80. Visual elements Video compression is also very sensitive to content Compression works by storing differences between subsequent frames – ”Car chase” – poor comp – ”TV speaker” – high comp

81. Visual elements Tips on creating video for the Web – Shoot original video – full quality control – Use close-ups – better for low resolution – Use simple backgrounds – better compression – Steady camera – better compression – Avoid zooming and panning – bad for low resolution, bad for compression – Use hard cuts, avoid ”silly” effects – bad for compression

82. Visual elements