The "ocropus" Command Line Tool

Simple Invocation

The most useful way of invoking OCRopus looks like

ocropus ocr page1.png page2.png page3.png > result.html

The output is in hOCR format. You can find tools for manipulating the format here.

Separate Segmentation / Line Recognition

These two command line interfaces are probably the most useful ones for testing and development of new layout analysis and character recognition engines.

ocropus layout prefix page1.png...

Extract (binary) lines from pages.

ocropus linerecs line1.png...

Recognize binary lines with adaptation.

Individual Processing Steps

You don't need these for normal OCR operations, but they are useful for testing, development, and prototyping.

ocropus linerec input

Recognize a single line.

ocropus binarize page.png page.bin.png

Binarize a page using Sauvola algoritm.

ocropus pageseg page.png page.plo.png

Compute a page segmentation; see http://misc.iupr.org/docs/doku.php?id=pub:ocropus:file-formats.

ocropus lineseg line.png line.cut.png

Segment a single line into sub-character components; see http://misc.iupr.org/docs/doku.php?id=pub:ocropus:file-formats.

Parameters

OCRopus takes parameters via the environment; here is a summary of the most useful ones.

   hocr=0 ./ocropus ocr input.png

If you're not using a Bourne shell, you may have to say:

   env hocr=0 ./ocropus ocr input.png

General options

adapt (0/1, default 1) Use adaptation. This option improves OCR quality, but lowers the speed. The bigger the page is, the larger the improvement will be. This option is better with spell=0 (the result of spellchecking might be strange).

hocr (0/1, default 1) Produce output in hOCR format (HTML with additional OCR-related markup). When this option is disabled, only the text is printed.

charseg_file (n/a by default) Output a character segmentation file.

charcut_file (n/a by default) Output a character cut file.

remove_hyphens (0/1, default 1) Join lines if a hyphenated word is detected.

spell (0/1, default 1) Apply spellchecking at the first pass.

verbose (0/1, default 0) Print all accepted options with brief descriptions. The printed list will be complete, unlike this one.

Binarization Options

k (default 0.5; range [0,1]) Controls the binarization threshold. In general, lower the value of k higher the number of black pixels in the image.