Post on 22-Dec-2015
Text, Graphics,Text, Graphics,Symbols, and CodesSymbols, and Codes
Chapter 4Chapter 4
Text, Graphics,Text, Graphics,Symbols, and CodesSymbols, and Codes
Visual Capabilities Visual Capabilities Hardcopy Hardcopy VDT Screens VDT Screens Graphic Representation Graphic Representation Symbols Symbols Codes Codes
Visual CapabilitiesVisual Capabilities
AccommodationAccommodation
Visual AcuityVisual Acuity
Contrast SensitivityContrast Sensitivity
Factors Affecting Visual Acuity and Contrast Factors Affecting Visual Acuity and Contrast SensitivitySensitivity
AdaptationAdaptation
Color DiscriminationColor Discrimination
ReadingReading
PerceptionPerception
Visual CapabilitiesVisual Capabilities
AccommodationAccommodation• Near point, Far pointNear point, Far point
• Diopters (D)=1/distance(m)Diopters (D)=1/distance(m)
• Dark focus: about at arm’s length (1m or 1D)Dark focus: about at arm’s length (1m or 1D)
Visual CapabilitiesVisual Capabilities
Visual Acuity: Visual Acuity: Discriminate fine detailDiscriminate fine detail
• Minimum separable acuity Minimum separable acuity Fig 4-2Fig 4-2
Visual angle (VA): VA (minutes) = 3438Visual angle (VA): VA (minutes) = 3438××H/D; H/D; Fig 4-3Fig 4-3
Acuity = 1 / VA (min)Acuity = 1 / VA (min)
• Other types of acuity: Other types of acuity:
Vernier acuityVernier acuity
Minimum perceptible acuity: detect dot from backgroundMinimum perceptible acuity: detect dot from background
Stereoscopic acuityStereoscopic acuity
Visual CapabilitiesVisual Capabilities
Contrast SensitivityContrast Sensitivity• Spatial frequency Spatial frequency Fig 4-2Fig 4-2 4-44-4 fig fig
• Modulation contrastModulation contrast C= (LC= (Lmaxmax -- LLminmin) / (L) / (Lmaxmax ++ LLminmin) )
• Threshold contrast, Contrast sensitivity Threshold contrast, Contrast sensitivity Fig 4-5Fig 4-5
Visual CapabilitiesVisual Capabilities
Factors Affecting Visual Factors Affecting Visual AcuityAcuity and Contrast and Contrast SensitSensitivityivity• Luminance level: Luminance level: cone vs. rodcone vs. rod
• Contrast: Contrast: contrastcontrast acuity acuity Modulation contrastModulation contrast Luminous contrast = (LLuminous contrast = (Lmaxmax -- LLminmin) / L) / Lmaxmax
Contrast (or luminance) ratio = LContrast (or luminance) ratio = Lmaxmax / / LLminmin
• Exposure time: Exposure time: improve up to 100-200msimprove up to 100-200ms
• Target motion: Target motion: dynamic visual acuitydynamic visual acuity
• Age Age
• TrainingTraining
HardcopyHardcopy
CriterionCriterion TypographyTypography (印刷體裁)(印刷體裁)
HardcopyHardcopy -- CriterionCriterion
VisibilityVisibility LegibilityLegibility ::易識別易識別 DiscriminabilityDiscriminability ReadabilityReadability :: Recognition of the information content Recognition of the information content
of material of material
(meaningful groupings: words, sentences, text…)(meaningful groupings: words, sentences, text…)
HardcopyHardcopy -- TypographyTypography
何時需設計較佳的 何時需設計較佳的 TypographyTypography :: Viewing ConditionsViewing Conditions :: unfavorableunfavorable
InformationInformation :: importantimportant
criticalcritical
Distant ViewingDistant Viewing
Poor Vision (People) Poor Vision (People)
HardcopyHardcopy -- TypographyTypography
Stroke Width Stroke Width (stroke width – to – height ratio)(stroke width – to – height ratio)
Fig 4-6Fig 4-6 4-74-7
• Normal: Normal: 白底黑字白底黑字 1:6 – 1:81:6 – 1:8 黑底白字黑底白字 1:8 – 1:101:8 – 1:10
• Illumination: lowIllumination: low→ thick→ thick
• Contrast: low→ thickContrast: low→ thick
• Highly luminous letter: thin 1:12 – 1:20Highly luminous letter: thin 1:12 – 1:20
• 黑字黑字 on on 亮背景亮背景 : very thick: very thick
HardcopyHardcopy -- TypographyTypography
Width-to-Height Ratio Width-to-Height Ratio Fig 4-8Fig 4-8
Styles of Type Styles of Type Tab 4-1Tab 4-1
• 一般一般 : Roman: Roman
• 斜體 斜體 (Italics): (Italics): 特殊用法 特殊用法 or or 重要者重要者• 粗體 粗體 (Bold): (Bold): 重點重點
HardcopyHardcopy -- TypographyTypography
SizeSize• Points: 1-pt = 1/72in (0.35mm) Points: 1-pt = 1/72in (0.35mm) (p.106)(p.106) • For Close-up ReadingFor Close-up Reading
一般一般 : 9 – 11 pt: 9 – 11 pt Luminance, Importance Luminance, Importance Tab 4-2Tab 4-2
• For Distance ReadingFor Distance Reading Subtend same visual angleSubtend same visual angle公式 公式 (p.107) (p.107) Tab 4-3Tab 4-3
HardcopyHardcopy -- TypographyTypography
CaseCase• 小寫小寫 : : 易讀 易讀 (( 因 因 envelop, e.g. pie, big, pienvelop, e.g. pie, big, pi
g)g)
• Search for particular labelSearch for particular label ““ 開頭字母”重要,宜特大開頭字母”重要,宜特大 (e.g.) (e.g.) CCase vs. Case; ase vs. Case; CCASE vs. CASEASE vs. CASE
Layout Layout Fig 4-9Fig 4-9
• Interletter spacingInterletter spacing (字距)(字距)• Interline spacingInterline spacing (行距)(行距)
HardcopyHardcopy -- TypographyTypography
Reading EaseReading Ease• Type of SentenceType of Sentence (句型)(句型) Simple, Affirmative, ActiveSimple, Affirmative, Active
• Order of WordsOrder of Words Match the order of actionMatch the order of action
• Index of Readability Index of Readability Tab 4-4Tab 4-4
Score = Score = 206.835206.835 -- (0.846× S) (0.846× S) -- (1.015× W)(1.015× W)
S: syllables of 100 wordsS: syllables of 100 words
W: no. of words per sentenceW: no. of words per sentence
VDT ScreensVDT Screens
基本性質基本性質 TypographyTypography Reading DistanceReading Distance
• 20 in (45cm)20 in (45cm)• Eye-to-screen=Eye-to-keyboard (Accommodation)Eye-to-screen=Eye-to-keyboard (Accommodation)
SizeSize Hardware ConsiderationsHardware Considerations
• PolarityPolarity• Color Color
Screen Design IssuesScreen Design Issues
VDT ScreensVDT Screens Screen Design IssuesScreen Design Issues
• Density Density Fig 4-11Fig 4-11
Global density: mean=25% Global density: mean=25% (600 data screens)(600 data screens)
Local densityLocal density the no. of filled character spaces near other charactersthe no. of filled character spaces near other characters
DensityDensity↑↑→ Performance→ Performance↓↓
Reduce density: Reduce density: Abbreviation, Avoid unnecessary information,Abbreviation, Avoid unnecessary information, Concise wordingConcise wording (簡潔)(簡潔) , Tabular format, Tabular format
VDT ScreensVDT Screens
• GroupingGrouping
Size of the groupsSize of the groups < < 55º (VA): No. º (VA): No. 愈少愈好愈少愈好 Size of the groupsSize of the groups >> 55ºº:: Size Size 愈小愈好愈小愈好
• ComplexityComplexity
Tullis (1983)Tullis (1983) Arrangement (layout) complexity:Arrangement (layout) complexity: The extent of The extent of arrangementarrangement follows a follows a predictablepredictable visual scheme visual scheme
Columnar arrangement Columnar arrangement Fig 4-12Fig 4-12
• Highlighting / Highlighting / BlinkingBlinking (end)(end)
Graphic RepresentationGraphic Representation Of TextOf Text
• 不受限於語言不受限於語言• Instruction, Procedure manualInstruction, Procedure manual
• Combine Pictorial & textCombine Pictorial & text Pictorial: speed; Text: accuracyPictorial: speed; Text: accuracy
Of DataOf Data• Pie chart, Bar chart, Line chartPie chart, Bar chart, Line chart
• 2-D, 3-D 2-D, 3-D Fig 4-13Fig 4-13
• Distortion: Distortion: Fig 4-14Fig 4-14
• Guideline: correct perception↑Guideline: correct perception↑
SymbolsSymbols
Symbolic vs. Verbal Signs Symbolic vs. Verbal Signs Fig 4-15Fig 4-15
Objectives of Symbolic Coding SystemsObjectives of Symbolic Coding Systems• Best Represent their Referent: depend on strength of Best Represent their Referent: depend on strength of assass
ociationociation of a of a symbolsymbol with its with its referentreferent
• Guideline: Guideline: Detectability, Discriminability, Compatibility, MeaningfuDetectability, Discriminability, Compatibility, Meaningfu
lness, Standardization lness, Standardization
Criteria for Selecting Coding SymbolsCriteria for Selecting Coding Symbols• RecognitionRecognition
• MatchingMatching
• Preference & OpinionsPreference & Opinions
SymbolsSymbols
Example of StudiesExample of Studies• Mandatory-Action Symbols Mandatory-Action Symbols Fig 4-16Fig 4-16
Original test, Second testOriginal test, Second test
Recognition Recognition 佳佳 Subjects:Subjects: 初臨澳洲的越南人 初臨澳洲的越南人 (different culture)(different culture)
• Exit Symbols Exit Symbols Fig 4-17Fig 4-17
Filled Filled
Background: Background: 方方>>圓圓 Simplified figureSimplified figure
SymbolsSymbols
Perceptual Principles Perceptual Principles Fig 4-18Fig 4-18
• Figure/GroundFigure/Ground
• Figure boundaryFigure boundary
• ClosureClosure
• SimplicitySimplicity
• UnityUnity StandardizationStandardization
• International road signs International road signs Fig 4-19Fig 4-19
(end)(end)
CodesCodes
Referents: the items to be codedReferents: the items to be codedCoding dimensions: types of visual sti. usedCoding dimensions: types of visual sti. used
Single Coding DimensionsSingle Coding Dimensions Color Color 最佳 最佳 (?)(?) Fig 4-20 4-21 Tab 4-5Fig 4-20 4-21 Tab 4-5
Color Coding (surface color)Color Coding (surface color) Hue: 9Hue: 9 Hue+Saturation+Brightness: 24Hue+Saturation+Brightness: 24 Visual search Visual search 佳佳 Meaning?Meaning?
Multidimensional Code Multidimensional Code Fig 4-22Fig 4-22