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 --no-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". The reports include the character
  error rate (CER) and the word error rate (WER).

  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 / --no-metrics  Enable/disable metrics and green/red
  --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 false`	Disable metrics and the green-red color scheme (default: enabled)
`-P textequiv_level line`	(PAGE) Extract text from TextLine level (default: TextRegion level)