Tesseract.js is a javascript library that gets words in [almost any language](./docs/tesseract_lang_list.md) out of images. ([Demo](http://tesseract.projectnaptha.com/))
Tesseract.js works with script tags, [webpack](https://webpack.js.org/), and [Node.js](https://nodejs.org/en/). [After you install it](#installation), using it is as simple as
Tesseract.js wraps an [emscripten](https://github.com/kripken/emscripten) [port](https://github.com/naptha/tesseract.js-core) of the [Tesseract](https://github.com/tesseract-ocr/tesseract) [OCR](https://en.wikipedia.org/wiki/Optical_character_recognition) Engine.
Tesseract.js works with a `<script>` tag via local copy or CDN, with webpack via `npm`, and on Node.js via `npm`. [Check out the docs](#docs) for a full treatment of the API.
-`options` is either absent (in which case it is interpreted as `'eng'`), a string specifing a language short code from the [language list](./docs/tesseract_lang_list.md), or a flat json object that may:
+ include properties that override some subset of the [default tesseract parameters](./docs/tesseract_parameters.md)
+ include a `lang` property with a value from the [list of lang parameters](./docs/tesseract_lang_list.md)
The main Tesseract.js functions take an `image` parameter, which should be something that is like an image. What's considered "image-like" differs depending on whether it is being run from the browser or through NodeJS.
On a browser, an image can be:
- an `img`, `video`, or `canvas` element
- a `File` object (from a file `<input>` or drag-drop event)
A TesseractJob is an object returned by a call to `recognize` or `detect`. It's inspired by the ES6 Promise interface and provides `then` and `catch` methods. It also provides `finally` method, which will be fired regardless of the job fate. One important difference is that these methods return the job itself (to enable chaining) rather than new.
In the browser, `tesseract.js` simply provides the API layer. Internally, it opens a WebWorker to handle requests. That worker itself loads code from the Emscripten-built `tesseract.js-core` which itself is hosted on a CDN. Then it dynamically loads language files hosted on another CDN.
Because of this we recommend loading `tesseract.js` from a CDN. But if you really need to have all your files local, you can use the `Tesseract.create` function which allows you to specify custom paths for workers, languages, and core.
A string specifying the location of the [tesseract.js-core library](https://github.com/naptha/tesseract.js-core), with default value 'https://cdn.jsdelivr.net/gh/naptha/tesseract.js-core@0.1.0/index.js'. Set this string before calling `Tesseract.recognize` and `Tesseract.detect` if you want Tesseract.js to use a different file.
A string specifying the location of the [worker.js](./dist/worker.js) file. Set this string before calling `Tesseract.recognize` and `Tesseract.detect` if you want Tesseract.js to use a different file.
A string specifying the location of the tesseract language files, with default value 'https://cdn.jsdelivr.net/gh/naptha/tessdata@gh-pages/3.02/'. Language file URLs are calculated according to the formula `langPath + langCode + '.traineddata.gz'`. Set this string before calling `Tesseract.recognize` and `Tesseract.detect` if you want Tesseract.js to use different language files.
Then open `http://localhost:7355/examples/file-input/demo.html` in your favorite browser. The devServer automatically rebuilds `tesseract.js` and `tesseract.worker.js` when you change files in the src folder.
After you've cloned the repo and run `npm install` as described in the [Development Section](#development), you can build static library files in the dist folder with
