UNDER CONTRUCTION

Due for Release on Monday, Oct 3, 2016

tesseract.js

Tesseract.js is a pure javascript version of the Tesseract OCR Engine that can recognize English, Chinese, Russian, and 60 other languages.

Installation

Tesseract.js works with a <script> tag via local copy or cdn, or with npm (if you're using webpack / browserify).

Script Tag

CDN

<script src='https://cdn.rawgit.com/naptha/tesseract.js/5ed4c0bc/dist/tesseract.js'></script>

<script>
var worker = createTesseractWorker('https://cdn.rawgit.com/naptha/tesseract.js/5ed4c0bc/dist/tesseract.worker.js')

worker.recognize('#my-image')
    .progress(function (p) { console.log('progress', p) })
    .then(function (result) { console.log('result', result) })
</script>

Local

First grab copies of tesseract.js and tesseract.worker.js from the dist folder. Then include tesseract.js on your page like this:

<script src='/path/to/tesseract.js'></script>

<script>
var worker = createTesseractWorker('/path/to/tesseract.worker.js')

worker.recognize('#my-image')
    .progress(function (p) { console.log('progress', p) })
    .then(function (result) { console.log('result', result) })
</script>

npm

TODO

Docs

Tesseract.recognize(image) -> TesseractJob

Returns a TesseractJob whose then method can be used to act on the result of the OCR.

For example:

image can be

• an img element or querySelector that matches an img element
• a video element or querySelector that matches a video element
• a canvas element or querySelector that matches a canvas element
• a CanvasRenderingContext2D (returned by canvas.getContext('2d'))
• the absolute url of an image from the same website that is running your script. Browser security policies don't allow access to the content of images from other websites :(

Tesseract.detect(image) -> TesseractJob

Returns a TesseractJob whose then method can be used to act on the result of the OCR.

For example:

image can be

• an img element or querySelector that matches an img element
• a video element or querySelector that matches a video element
• a canvas element or querySelector that matches a canvas element
• a CanvasRenderingContext2D (returned by canvas.getContext('2d'))
• the absolute url of an image from the same website that is running your script. Browser security policies don't allow access to the content of images from other websites :(

TesseractJob

A TesseractJob is an an object returned by a call to recognize or detect. All methods of a TesseractJob return itself to enable chaining.

Typical use is:

var job1 = Tesseract.recognize('#my-image')

job1.progress(function(message){console.log(message)})
    .error(function(err){console.error(err)})
    .then(function(result){console.log(result)})

or more concisely:

Tesseract.recognize('#my-image')
    .progress(function(message){console.log(message)})
    .error(function(err){console.error(err)})
    .then(function(result){console.log(result)})

TesseractJob.progress(callback: function) -> TesseractJob

Sets callback as the function that will be called every time the job progresses.

callback is a function with the signature callback(progress) where progress is json object.

For example:

Tesseract.recognize('#my-image')
    .progress(function(message){console.log('progress is: 'message)})

The console will show something like:

progress is: {loaded_lang_model: "eng", from_cache: true}
progress is: {initialized_with_lang: "eng"}
progress is: {set_variable: Object}
progress is: {set_variable: Object}
progress is: {recognized: 0}
progress is: {recognized: 0.3}
progress is: {recognized: 0.6}
progress is: {recognized: 0.9}
progress is: {recognized: 1}

TesseractJob.then(callback: function) -> TesseractJob

Sets callback as the function that will be called if and when the job successfully completes.

For example:

Tesseract.recognize('#my-image')
    .then(function(result){console.log('result is: 'result)})

The console will show something like:

progress is: {
    blocks: Array[1]
    confidence: 87
    html: "<div class='ocr_page' id='page_1' ..."
    lines: Array[3]
    oem: "DEFAULT"
    paragraphs: Array[1]
    psm: "SINGLE_BLOCK"
    symbols: Array[33]
    text: "Hello World↵from beyond↵the Cosmic Void↵↵"
    version: "3.04.00"
    words: Array[7]
}

TesseractJob.error(callback: function) -> TesseractJob

Sets callback as the function that will be called if and when the job successfully completes.

Contributing

Development

To run a development copy of tesseract.js, first clone this repo.

> git clone https://github.com/naptha/tesseract.js.git

Then, cd in to the folder, npm install, and npm start

> cd tesseract.js
> npm install && npm start

  ... a bunch of npm stuff ... 

  tesseract.js@1.0.0 start /Users/guillermo/Desktop/code_static/tesseract.js
  node devServer.js

Listening at http://localhost:7355

Then open http://localhost:7355 in your favorite browser. The devServer automatically rebuilds tesseract.js and tesseract.worker.js when you change files in the src folder.

Building Static Files

After you've cloned the repo and run npm install as described in the Development Section, you can build static library files in the dist folder with

> npm run build

Send us a Pull Request!