Download Using Computer Vision to Test Web Display

Using Computer Vision
to Test Web Display
Xu Liu
liuxu@cs.umd.edu
Why test web display?
 Display Bugs
Bug
“Opera 7.54”
Normal
IE6
More bugs
BUG - Opera
Normal - Firefox
Normal - IE
Normal - Mozilla
Where comes these bugs?
 Different parsers on DHTML, CSS
 Web designer doesn’t follow W3C
standard
 IE tolerant buggy HTML
 Java Script, ActiveX, Flash
Which kinds of bugs do we
have?
 Text/Image Overlap
 Incorrect blank area
 Missing Text/Image
Generally they are all
layout problems
How do we detect these
bugs
 Is HTML source helpful?
 Yes, but we need a correct parser which is
being tested
 HTML does not have straight forward
relationship with display
 Eyes always tell the truth – directly use
the image of snapshot
Find the outlier
 Let them vote:
 IE, Firefox, Mozilla, Netscapte, Opera,
MyIE…
 Anyone seems distinct from others is
probably an outlier
 Assumption : Major are correct, Minor are
incorrect
Basic Question
 How do we compare 2 images? Are they same?
Missing
Front and
end
These 2 look
different but
they should be
considered the
same
Simpler Question
 How do we compare 2 sequences?
S1: 1 2 3 4 5 6 8 7
Direct Compare
|S1-S2|=0+0+1+1+0+1+2+0=5
S2: 1 2 4 5 5 5 6 7
Dynamic Time Warping !!
In fact ||S1-S2||=0,
they should be considered the same
Dynamic Time Warping
(DTW)
 A widely used technique in signal processing
 Speech recognition, Image matching
Compare S1,S2
Diff (0,0)  0
Diff (i, j )  min {Diff (k , j  1) | S1(i)  S 2( j ) |}
i1 k i 2
| S1  S 2 | Diff ( S1.length(), S 2.length())
Can we directly apply
DTW to compare web
pages?
 No!
If we directly compare 2 pages:
Most of the error will be omitted
Local VS Global
Segmentation First!!
A Segmented Page
How do we derive
segmentations
Edge Detection First
Over Segment
Merge
Next
 For every page
 We have all its segments
 For every segment
 If it CANNOT be found in other pages,
possibly it is an error
Result
http://www.microsoft.com/smallbusiness/default.mspx by Opera 7.54
Result
http://www.microsoft.com/learning/default.asp by Opera 7.54
Shortage and Future Work
 Make segmentation more accurate
 Make the system completely automatic