fast retrieval of old dropcap images mathieu delalandre, jean-marc ogier and josep llados idoc...
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Fast Retrieval of Old Dropcap Images
Mathieu Delalandre, Jean-Marc Ogier and Josep Llados
IDoc Meeting
Valencia, Spain
22th February 2007
Fast Retrieval of Old Dropcap Images
Dropcaps in old books of XV° and XVI° Problematics
(1) Historian people are interested to retrieve similar printings
Wood plug(bottom
view)
Plug 1 Plug 2 Plug 3
Printing 1
Printing 2
(2) Several large databases are available on the web, a system must retrieve in real-time in order to allow cross queries
DB
DB
DB
query
query
r1 r2 r3
r1 r2 r3
Level 1 : image sizes Level 2 : image densityLevel 3 : RLE comparison
2121
2121
,max,max vvuu
vvuud
Our system (1/2)Our key ideas
(2) To use different level of operator (from more speed to more accurate)
query
1st Level
2sd Level
Speed
Depth
(1) To use a Run Length Encoding (RLE) of Image
Compression rate/Dropcap
0,7
0,8
0,9
1
Dropcap
Co
mp
res
sio
n r
ate
0.75
0.950.8
8
x2 x2 x2
x1x1 x1
x2
line (y) image
1
3
1
2 4
5 6
7line (y+dy)
image 2
while x1 x2 handle image 1
while x2 x1 handle image 2
Fast Retrieval of Old Dropcap Images
Our system (2/2)
2
clusterthreshold
Distance curve
00,10,20,30,40,50,60,70,8
1 167 333 499 665 831 997 1163 1329 1495 1661 1827 1993
Dropcap
Dis
tan
ce
1
2if 1 - 2 < 0
push x, cluster
while 1 - 2 < 0
next
Fast Retrieval of Old Dropcap Images
To switch between levels we use the ‘elbow criteria’
Results
32.89 s903.62 sMax
10.00 s337.06 sMean
05.35 s176.67 sMin
Our system
Raster comparisonQuery times
(laptop 1.8GHZ)
250 to 350 dpiResolutions
UncompressCompression
TiffFormat
grayModel
279.7 MoSize
2038Files
Test database
around 30 timesmore faster
0.1947 0.2517 0.3485 0.3616 0.3819 0.4064
Same plug
Next plug
Query
0.4109 0.4209
Example of query result
Fast Retrieval of Old Dropcap ImagesWorks in progress …
BaseOur
Retrieve engine
control
display
retrieve
Labels
driven labelling
Bench1 Bench2 Bench2To produce
To use our system like a groundtruthing one to evaluate retrieval results
0
5
10
15
20
25
30
35
40
0
5
10
15
20
25
30
35
40
To use a run based signature as additional level to speed up again the process
Application perspectives
To implement the engine on BVH website in next months
http://www.bvh.univ-tours.fr/
Contacts in progress with the EVODIA company to develop a commercial software
http://www.evodia.fr/