2.9 KiB
Local Installation
Check here for examples: https://github.com/naptha/tesseract.js/blob/master/docs/examples.md
In browser environment, 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 pass extra arguments to TesseractWorker to specify custom paths for workers, languages, and core.
In Node.js environment, the only path you may want to customize is languages/langPath.
Tesseract.recognize(image, langs, {
workerPath: 'https://cdn.jsdelivr.net/npm/tesseract.js@v4.0.3/dist/worker.min.js',
langPath: 'https://tessdata.projectnaptha.com/4.0.0',
corePath: 'https://cdn.jsdelivr.net/npm/tesseract.js-core@v4.0.3',
})
Or
const worker = await createWorker({
workerPath: 'https://cdn.jsdelivr.net/npm/tesseract.js@v4.0.3/dist/worker.min.js',
langPath: 'https://tessdata.projectnaptha.com/4.0.0',
corePath: 'https://cdn.jsdelivr.net/npm/tesseract.js-core@v4.0.3',
});
workerPath
A string specifying the location of the worker.js file.
langPath
A string specifying the location of the tesseract language files, with default value 'https://tessdata.projectnaptha.com/4.0.0'. Language file URLs are calculated according to the formula langPath + langCode + '.traineddata.gz'.
corePath
A string specifying the location of the tesseract.js-core library, with default value 'https://cdn.jsdelivr.net/npm/tesseract.js-core@v4.0.3'.
When corePath is a directory rather than specific .js file (e.g. https://cdn.jsdelivr.net/npm/tesseract.js-core@v4.0.3), Tesseract.js loads either tesseract-core-simd.wasm.js or tesseract-core.wasm.js depending on whether the users' device supports SIMD (see https://webassembly.org/roadmap/). Therefore, if self-hosting it is important that both these files are in the location you specify for corePath. Having multiple files is necessary as the SIMD-enabled version is significantly faster (for the LSTM model [the default]), however is not yet supported on all devices.
When corePath is set to a specific .js file (e.g. https://cdn.jsdelivr.net/npm/tesseract.js-core@v4.0.3/tesseract-core.wasm.js), it will load that file regardless of whether the users' device supports SIMD or not. This behavior exists to preserve backwards compatibility--specifying a directory that contains both files is strongly recommended. Specifying a single file will either result in much slower performance (if tesseract-core.wasm.js is specified) or failure to run on certain devices (if tesseract-core-simd.wasm.js is specified).