Khmer OCR scientific day at ITC

1. Khmer OCR
LONG Seangmeng
Lecturer and researcher, GIC - ITC
seangmeng@itc.edu.kh
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Scientific Day
3th May, 2012

2. Khmer OCR
• What is OCR?
• Khmer OCR Project
• State of the Art
• Khmer OCR System
• Project status
• Perspectives
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3. Optical Character Recognition (OCR)
OCR
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Text Image
Editable Text

4. Khmer OCR Project
• 2011
• Team
– Dr. SENG Sopheap, ITC
– Mr. LONG Seangmeng, ITC
– Mr. EN Sovann (doing master)
– Ms. PRUM Sophea (doing PhD)
– Mr. HAO Jeudi (5th year)
• Develop a Khmer OCR system
– Font independent
– Size independent
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5. State of the Art
Author Limitation Result
CHEY Chanoeurn, KOSIN
Chamnongthai and PINIT
Kumhom
10 characters (បពជកភណឃសវទ) 92%
CHEY Chanoeurn, KOSIN
Chamnongthai and PINIT
Kumhom
20 fonts 92.85% (size 22)
91.66% (size 18)
89.27% (size 12)
ING Leng Ieng and MUAZ
Ahmed
Limon R1 22 98.88%
KRUY Vanna Font and size independent
(manual preparation for
new fonts)
97%
EN Sovann Font and size independent
(manual preparation for
new fonts)
96%
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6. Khmer OCR System
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Pre processing
Segmentation
Recognition
Post processing
Text Image
Editable Text
សា លា ្រ ក រ ង រ ភ រន
សាលា្កុងភនពពញនិងសហជីព

7. Khmer OCR System (cont.)
• Pre processing
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Binarization
Noise removal
Skew detection
and correction

8. Khmer OCR System (cont.)
• Segmentation
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Line
Vertical Symbol
Blob
Page
Line 1
Line 2

9. Khmer OCR System (cont.)
• Recognition
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Blob
Training images (sample images) with label
…
Blob to be recognized
Search for closest
match
Closest match
Image:
Label: ក

10. Khmer OCR System (cont.)
• Recognition (cont.)
– How to find closest match?
– How to represent the blob image?
• Fourier transform: Any function f(t) with period T can be written as
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Blob image => 2-D Fourier transform
The blob image (B) represented by Fourier coefficients:
B[0], B[1], B[2], …
City block distance between two blobs B and B’:
Distance = |B[0] – B’[0]| + |B[1] – B’[1]| + |B[2] – B’[2]| + …

11. Khmer OCR System (cont.)
• Post processing
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ឦ
ញ
Assembling
Blob
សា លា ្រ ក រ ង រ ភ រន ពរ ព ញ រិ ន ង
សា លា ្រក រ ង រភ រន ពរព ញ រិន ង
សា្លាកងពភនពញិនង
សាលា្កុងភនពពញ
Reordering
កន
្រុង ្កុង
ពបស់
ភន
របស់
Spell Checking

12. Project status
• Pre processing
– Binarization and noise removal √
– Skew detection and correction X
• Segmentation √
• Recognition
– Features extraction √
– Automatic generation of training data for new fonts √
• Post processing
– Assembling and reordering rules
• Manual √
• Automatic X
– Spell checking X
• Performance evaluation X
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13. Perspectives
• Joining characters
• Text layout
• Low quality text images
• Curve line
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14. Thanks for your attention!
Demo & Questions???
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