dinglehopper

dinglehopper is an OCR evaluation tool and reads ALTO, PAGE and text files. It compares a ground truth (GT) document page with a OCR result page to compute metrics and a word/character differences report.

Goals

• Useful
  • As a UI tool
  • For an automated evaluation
  • As a library
• Unicode support

Installation

It's best to use pip, e.g.:

sudo pip install .

Usage

Usage: dinglehopper [OPTIONS] GT OCR [REPORT_PREFIX]

  Compare the PAGE/ALTO/text document GT against the document OCR.

  dinglehopper detects if GT/OCR are ALTO or PAGE XML documents to extract
  their text and falls back to plain text if no ALTO or PAGE is detected.

  The files GT and OCR are usually a ground truth document and the result of
  an OCR software, but you may use dinglehopper to compare two OCR results. In
  that case, use --metrics='' to disable the then meaningless metrics and also
  change the color scheme from green/red to blue.

  The comparison report will be written to $REPORT_PREFIX.{html,json}, where
  $REPORT_PREFIX defaults to "report". Depending on your configuration the
  reports include the character error rate (CER), the word error rate (WER)
  and the flexible character accuracy (FCA).

  The metrics can be chosen via a comma separated combination of their acronyms
  like "--metrics=cer,wer,fca".

  By default, the text of PAGE files is extracted on 'region' level. You may
  use "--textequiv-level line" to extract from the level of TextLine tags.

Options:
  --metrics                 Enable different metrics like cer, wer and fca.
  --textequiv-level LEVEL   PAGE TextEquiv level to extract text from
  --progress                Show progress bar
  --help                    Show this message and exit.

For example:

dinglehopper some-document.gt.page.xml some-document.ocr.alto.xml

This generates report.html and report.json.

dinglehopper-extract

The tool dinglehopper-extract extracts the text of the given input file on stdout, for example:

dinglehopper-extract --textequiv-level line OCR-D-GT-PAGE/00000024.page.xml

OCR-D

As a OCR-D processor:

ocrd-dinglehopper -I OCR-D-GT-PAGE,OCR-D-OCR-TESS -O OCR-D-OCR-TESS-EVAL

This generates HTML and JSON reports in the OCR-D-OCR-TESS-EVAL filegroup.

The OCR-D processor has these parameters:

Parameter	Meaning
-P metrics cer,wer	Enable character error rate and word error rate (default)
-P textequiv_level line	(PAGE) Extract text from TextLine level (default: TextRegion level)

For example:

ocrd-dinglehopper -I ABBYY-FULLTEXT,OCR-D-OCR-CALAMARI -O OCR-D-OCR-COMPARE-ABBYY-CALAMARI -P metrics cer,wer

Developer information

Please refer to README-DEV.md.