Node-tesseract OCR Windows使用小结

1.首先安装 Tesseract-OCR (windows )

  Github

   Wiki

2.设置环境变量

    1)PATH 增加  tesseract 安装目录

    2)新增系统变量 TESSDATA_PREFIX='安装目录文件夹下\tessdata'

3.nodejs 调用

 安装wraper，npm install node-tesseract

var tesseract = require('node-tesseract');

// Recognize text of any language in any format

tesseract.process(__dirname+'/test.png',function(err, text) {

    if(err) {

            console.error(err);

   } else {

             console.log(text);

              }

       });

4. 多语言

通过-l 选项，依次增加语言

tesseract imagename outputbase [-l lang] [-psm pagesegmode] [configfile...]

var options = {

l: 'chi_sim+eng',

psm: 6,

};

tesseract.process(__dirname + '/test.jpg', options, function(err, text) {

if(err) {

console.error(err);

} else {

console.log('----------------------------W');

console.log(text);

}

});

-psm:Member name Value Description

PSM_OSD_ONLY 0 Orientation and script detection only.

PSM_AUTO_OSD 1 Automatic page segmentation with orientation and script detection. (OSD)

PSM_AUTO_ONLY 2 Automatic page segmentation, but no OSD, or OCR.

PSM_AUTO 3 Fully automatic page segmentation, but no OSD.

PSM_SINGLE_COLUMN 4 Assume a single column of text of variable sizes.

PSM_SINGLE_BLOCK_VERT_TEXT 5 Assume a single uniform block of vertically aligned text.

PSM_SINGLE_BLOCK 6 Assume a single uniform block of text. (Default.)

PSM_SINGLE_LINE 7 Treat the image as a single text line.

PSM_SINGLE_WORD 8 Treat the image as a single word.

PSM_CIRCLE_WORD 9 Treat the image as a single word in a circle.

PSM_SINGLE_CHAR 10 Treat the image as a single character.

PSM_SPARSE_TEXT 11 Find as much text as possible in no particular order.

PSM_SPARSE_TEXT_OSD 12 Sparse text with orientation and script det.

PSM_RAW_LINE 13 Treat the image as a single text line, bypassing hacks that are Tesseract-specific.

5.配合 GraphicsMagick 识别验证码的例子

   参考链接    gm

6.Localized OCR(识别特定区域）

有时候需要识别特定区域，可以通过UZN 文件配合 -psm 4参数实现

Tesseract can read in uzn files, and use them instead of doing its own segmentation, on two conditions:

The segmentation mode PSM_SINGLE_COLUMN must be used (Check manpage for details)

The uzn file must be named imageName.uzn, so for scan01.png the uzn file must be named scan01.uzn

两个前提：

-psm 4

uzn 文件与图片文件名称相同

https://github.com/charlesw/tesseract/issues/66

例如，考虑有内容如下的图片test.png：

This is a text

            This is another test

      This is a last test

test.uzn:

50 65 100 15 Text

命令行输入：

 "tesseract.exe test.png test -psm 4"

输出结果：

This is another test

7. node-tesseract 增加hocr输出

两种方法：

1） 首先修改安装目录下  \lib\tesseract.js ，第22行处options增加hocr属性

options: {

           'l': 'eng',

          'psm': 3,

          'config': null,

          'binary': 'tesseract',

          'hocr':null

},

70行增加：

if (options.hocr !== null) {

command.push('hocr');

}

如果想要输出hocr格式，参考：

var options = {

          l: 'chi_sim+eng',

          psm: 4,

          hocr:'hocr'

};

tesseract.process( '/test.png', options, function(err, text) {

          if(err) {

                    console.error(err);

        } else {

                console.log(text);

          }

        });

2）参考 Git pull request，好像没更新，需要修改到自己的 tesseract.js 文件中