kba / page-to-alto

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

ocrd-page-to-alto

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

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