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ocrd-page-to-alto

Convert PAGE (v. 2019) to ALTO (v. 2.0 - 4.2)

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Introduction

This software converts PAGE XML files to the ALTO XML OCR result format. It enables using PAGE XML generating software in a context where ALTO is needed to display the results, i.e. in libraries.

Installation

In a Python virtualenv:

make install     # or pip install .
# or to install from PyPI
pip install ocrd_page_to_alto

Usage

To convert the PAGE XML document example.xml to ALTO:

page-to-alto example.xml > example.alto.xml

You can get an exhaustive list of page-to-alto's many options with --help:

CLI

Usage: page-to-alto [OPTIONS] FILENAME
  Convert PAGE to ALTO
Options:
  -l, --log-level [OFF|ERROR|WARN|INFO|DEBUG|TRACE]
                                  Log level
  --alto-version [4.2|4.1|4.0|3.1|3.0|2.1|2.0]
                                  Choose version of ALTO-XML schema to produce
                                  (older versions may not preserve all
                                  features)
  --check-words / --no-check-words
                                  Check whether PAGE-XML contains any Words
                                  and fail if not
  --check-border / --no-check-border
                                  Check whether PAGE-XML contains Border or
                                  PrintSpace
  --skip-empty-lines / --no-skip-empty-lines
                                  Whether to omit or keep empty lines in PAGE-
                                  XML
  --trailing-dash-to-hyp / --no-trailing-dash-to-hyp
                                  Whether to add a  element if the last
                                  word in a line ends in "-"
  --dummy-textline / --no-dummy-textline
                                  Whether to create a TextLine for regions
                                  that have TextEquiv/Unicode but no TextLine
  --dummy-word / --no-dummy-word  Whether to create a Word for TextLine that
                                  have TextEquiv/Unicode but no Word
  --textequiv-index INTEGER       If multiple textequiv, use the n-th
                                  TextEquiv by @index
  --textequiv-fallback-strategy [raise|first|last]
                                  What to do if nth textequiv isn't available.
                                  'raise' will lead to a runtime error,
                                  'first' will use the first TextEquiv, 'last'
                                  will use the last TextEquiv on the element
  -O, --output-file FILE          Output filename (or "-" for standard output,
                                  the default)
  -h, --help                      Show this message and exit.

To process an OCR-D workspace, use ocrd_fileformat, which uses page-to-alto by default:

ocrd-fileformat-transform -I OCRD-OCR-OUTPUT-PAGE -O OCRD-OCR-OUTPUT-ALTO \
  -P script-args "--dummy-word --no-check-words --no-check-border"

TODO

  • AlternativeImage
  • unmappable regions
  • handle Border
  • TextStyle
  • ParagraphStyle
  • table regions
  • recursive regions for *Region
  • Set PAGECLASS from pc:Page/@type #4
  • Layers / z-level via StructureTag? #4
  • <SP/>
  • <HYP/>
  • rotation
  • reading order
  • input PAGE-XML not having words #5
  • multiple pc:TextEquivs
  • language
  • script no equivalent in ALTO :(
  • kerning no equivalent in ALTO :(
  • underlineStyle no equivalent in ALTO :(
  • bgColour no equivalent in ALTO :(
  • bgColourRgb no equivalent in ALTO :(
  • reverseVideo no equivalent in ALTO :(
  • xHeight no equivalent in ALTO :(
  • letterSpaced no equivalent in ALTO :(
  • ProcessingStep
  • differentiate/select ALTO versions