1
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2
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- Screen readers
- Images cannot be read
- W3C accessibility standards
- “Provide a text equivalent for every non-text element”
- What if no alternative text?
- Nothing
- Filename (060315_banner_253x100.gif)
- Link address (http://www.cs.washington.edu)
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3
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4
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5
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- Web Studies
- Providing Labels
- WebInSight System
- Evaluation
- Future Work
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6
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- Significant images need alternative text
- Informative
- alt, title, and longdesc HTML
attributes
- Insignificant images need empty alt text
- Automatic Determination?
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7
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- Previous studies
- img tags with defined alt
attribute:
- 27.9%[1], 47.7%[2], and 49.4%[2]
- Significant images have a
defined alt attribute?
- Gaps
- Some Ignore Image Significance
- Some Ignore Image Importance
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8
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- University of Washington CSE Department Traffic
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9
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10
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- Web Studies
- Providing Labels
- WebInSight System
- Evaluation
- Future Work
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11
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- Many important images are links
- Linked page often describes
image
- What happens if you click
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12
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13
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- Humans are best
- Recent games compel accurate labeling
- WebInSight database has over 10,000 images
- Could do this on demand
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14
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- Web Studies
- Providing Labels
- WebInSight System
- Evaluation
- Future Work
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15
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- Tasks
- Coordinate multiple labeling
sources
- Insert alternative text into
web pages
- Add code to insert alternative
text later
- Features
- Browsing speed preserved
- Alternative text available when
formulated
- Immediate availability next
time
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16
|
|
17
|
- Web Studies
- Providing Labels
- WebInSight System
- Evaluation
- Future Work
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18
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- Measuring System Performance
- WebInSight tested on web pages
from web studies
- Used Context and OCR Labelers
- Labeled 43.2% of unlabeled,
significant images
- Sampled 2500 for manual
evaluation
- 94.1% were correct
- Proper Precision/Recall Trade-off
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19
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20
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- Lack of alternative text is pervasive
- WebInSight calculates alternative text
- WebInSight inserts alternative text
- High precision and moderate recall
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21
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- User Studies
- What do users want?
- How can we provide it?
- Maintain experience.
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22
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