Since Sep 8, 2008 / Last update: Aug 30, 2014

Introduction

NHocr is a command line OCR (Optical Character Recognition) program for Japanese language, etc. It has been designed to recognize machine-printed Japanese characters and some ASCII characters/symbols in an image. NHocr is probably the first Open Source Japanese OCR software (offline, machine-printed), except some experimental, partial codes open to academic communities.

You can also use NHocr through WeOCR service at: * http://maggie.ocrgrid.org/nhocr/

The program is highly experimental, and the character recognition performance is limited. (You would become happier with a commercial product if you want a high performance OCR.)

The character feature used in NHocr is based on Peripheral Local Moment (P-LM) proposed by Hori et al. in late 90's.

NHocr is originally a product of the author's weekend programming. The development work may be rather slow.

Change of the source package repository (important)

The source package repository has been changed to SourceForge.JP since Google removed "Downloads" feature at Google Code. The conventional tar-ball distribution is preferred in this project. This project page remains so you can find older versions.

The newer NHocr packages and supporting materials can be found at: * https://sourceforge.jp/projects/nhocr/

Limitations of the current version

• The current NHocr can handle text block image only, since it has not been equipped with a page layout analysis engine.
• The recognition accuracy may deteriorate when wide and narrow characters are mixed or when proportional fonts are used.
• The character segmentation performance is limited, since a primitive segmentation algorithm is used in the current version.
• The recognition accuracy with ASCII characters may not be so good. Using another OCR, such as tesseract, is recommended for European languages.
• The language post-processor "gramd" is experimental and works with Japanese text only. Some side effects may exist.

Supported platforms and requirements

Solaris SPARC/x86 and Linux are officially supported. NHocr would work on other UNIX(-like) platforms and MS-Windows.

NHocr uses FreeType 2 available at: * http://www.freetype.org/

NHocr 0.21 and older depend on O2-tools package available at: * http://www.imglab.org/p/O2/

Supported languages

The current version of NHocr supports Japanese only.

The author is interested in supporting other oriental languages such as Chinese. Character code table cctable-xxx is required. Contributions are welcome.

License

Apache License 2.0 applies to newer versions.

A derivative of MIT-X applies to version 1.5e-32 and older.