Optical Music Recognition

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Optical Music Recognition

• Ichiro Fujinaga
• McGill University
• 2003

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Content

• Optical Music Recognition
• Levy Project
• Levy Sheet Music Collection
• Digital Workflow Management
• Gamera
• Guido / NoteAbility

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Optical Music Recognition (OMR)

• Trainable open-source OMR system in development
  since 1984
• Staff recognition and removal
• Run-length coding
• Projections
• Lyric removal / classifier
• Stems and notehead removal
• Music symbol classifier
• Score reconstruction
• Demo

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OMR Classifier

• Connected-component analysis
• Feature extraction, e.g
• Width, height, aspect ratio
• Number of holes
• Central moments
• k-nearest neighbor classifier
• Genetic algorithm

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Overall Architecture for OMR
Image File
Staff removal Segmentation
Recognition K-NN Classifier
Output Symbol Name
Optimization Genetic Algorithm K-nn Classifier
Knowledge Base Feature Vectors
Best Weight Vector
Off-line
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Lester S. Levy Collection
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Lester S. Levy Collection

• North American sheet music (17801960)
• Digitized 29,000 pieces
• including The Star-Spangle Banner and Yankee
  Doodle
• Database of
• text index records
• images of music (8bit gray)
• lyrics (first lines of verse and chorus)
• color images of cover sheets (32bit)http//levysh
  eetmusic.mse.jhu.edu

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Digital Workflow Management

• Reduce the manual intervention for large-scale
  digitization projects
• Creation of data repository (text, image, sound)
• Optical Music Recognition (OMR)
• Gamera
• XML-based metadata
• composer, lyricist, arranger, performer, artist,
  engraver, lithographer, dedicatee, and publisher
• cross-references for various forms of names,
  pseudonyms
• authoritative versions of names and subject terms
• Music and lyric search engines
• Analysis toolkit

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The problem

• Suitable OCR for lyrics not found
• Commercial OCR systems are often inadequate for
  non-standard documents
• The market for specialized recognition of
  historical documents is very small
• Researchers performing document recognition often
  re-invent the basic image processing wheel

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The solution

• Provide easy to use tools to allow domain experts
  (people with specialized knowledge of a
  collection) to create custom recognition
  applications
• Generalize OMR for structured documents

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Introducing Gamera

• Framework for creation of structured document
  recognition system
• Designed for domain experts
• Image processing tools (filters, binarizations,
  etc.)
• Document segmentation and analysis
• Symbol segmentation and classification
• Feature extraction and selection
• Classifier selection and combiners
• Syntactical and semantic analysis
• Generalized Algorithms and Methods for
  Enhancement and Restoration of Archives

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Features of Gamera

• Portability (Unix, Windows, Mac)
• Extensibility (Python and C plugins)
• Easy-to-use (experts and programmers)
• Open source
• Graphic User Interface
• Interactive / Batchable (scripts)

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Architecture of Gamera
Graphic User Interface (wxWindows)
Plugins (Python)
Plugins (C)
GAMERA Core (C)
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Example of C Plugin

• // Number of pixels in matrix
• include gamera.hh
• ifdef __area_wrap__
• define NARGS 1
• define ARG1_ONEBIT
• endif
• using namespace Gamera
• template ltclass Tgt
• feature_t area(T m)
• return feature_t(m.nrows() m.ncols())

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Example of Python Plugin

• // This filters a list of CC objects
• import gamera
• def filter_wide(ccs, max_width)
• tmp
• for x in ccs
• if x.ncols() gt max_width
• x.fill_matrix(0)
• else
• tmp.append(x)
• return tmp

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Gamera Interface(screenshot in Linux)
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Gamera Interface(screenshot in Linux)
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Histogram(screenshot in Linux)
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Thresholding(screenshot in Linux)
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Thresholding(screenshot in Linux)
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Staff removal Lute tablature
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(No Transcript)
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Classifier Lute(screenshot in Linux)
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Staff removal Neums
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Classifier Neums(screenshot in Linux)
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Greek example
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GUIDO Music Notation FormatH. Hoos, K. Renz, J.
Kilian

• A formal language for score-level
  representation
• Plain text readable, platform independent
• Extensible and flexible
• Adequate representation
• NoteServer Web/Windows
• GUIDO/XML
• NoteAbility (K. Hamel)

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GUIDO An example
\beamsOff \cleflt"treble"gt \keylt"D"gt
f1/8. g1/16 a1/4. d21/8 d1/4. c1/8
e11/2 _1/4 f1/8. g1/16 c21/4. b11/8
a1/4. g1/8 e1/2 f1/4 f1/8. g1/16
a1/4. d21/8 d1/4. c1/8 e11/2 _1/4
f1/8 g c21/4. b11/8 a1/4. c1/8 ,
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NoteAbility Demo
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Conclusions

• Gamera allows rapid development of
  domain-specific document recognition applications
• Domain experts can customize and control all
  aspects of the recognition process
• Includes an easy-to-use interactive environment
  for experimentation
• Beta version available on Linux
• OS X version in preparation

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Projections

• X-projections

Y-projections
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