1.首先安装 Tesseract-OCR (windows )
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
