Vietnamese OCR

How Vietnamese OCR works

Drop a photo of a Vietnamese document, a book page, a receipt or a screenshot, and the text is recognised and saved as Unicode Vietnamese for Word, Google Docs, Zalo or a translator, with the accents in place.

Vietnamese uses the Latin alphabet with some of the densest diacritics of any language: vowel marks that make ă, â, ê, ô, ơ and ư, the letter đ, and five tone marks on top of those, so a single vowel can carry two marks, as in ệ, ở or ữ. Reading a Vietnamese page with English selected strips almost all of them. The Vietnamese model is trained to output each accented letter, which is what keyboards and search engines expect.

Tone marks are small and sit close to the vowel marks, so they are the first thing lost in low-resolution images: ở can become ơ, and ệ can become ê. Stacked marks also need room above the line, so tightly cropped lines lose them. Check names and prices in the result, where one wrong tone changes the meaning.

The Vietnamese model, about 1.4 MB, downloads from the jsDelivr CDN the first time you press the button and is cached, along with the OCR engine of about 4 MB, so later images start straight away. The image itself is read inside this tab and never uploaded. The result is a UTF-8 text file named after the image. For an editable Word document instead, use Image to Word and choose Vietnamese.

Vietnamese OCR options explained

When to use it

Use Vietnamese OCR to copy text from a scanned contract or certificate, to get the text of a photographed book or newspaper into a document, to search receipts and invoices, or to paste Vietnamese into a translator.

Leave some margin above the top line when you crop, so the tone marks on capital letters are not cut off, and use an image large enough that each accent is a clear shape.

About the OCR engine

Text recognition uses Tesseract, the open-source OCR engine first developed at HP, then for many years at Google, and now maintained by its open-source community. Its current generation reads whole lines of text with a neural network (an LSTM) rather than matching letters one at a time, which is what lets it handle joined scripts such as Arabic and Devanagari. Tesseract.js compiles it to WebAssembly so it runs in this tab. Each language has its own trained model, downloaded from the jsDelivr CDN only when that language is chosen and then cached, so reading English never downloads Hindi, and the other way round. The models used here are the integer versions of Tesseract's most accurate models, which keep nearly all of their accuracy at a fraction of the size. Tesseract is built for printed text: it reads books, letters, forms, signs and screenshots well, handwriting poorly, and it keeps the words of a page in reading order but not its layout.

Vietnamese OCR troubleshooting

Accents are missing

Check that Vietnamese, not English, is selected, then use a sharper, larger image.

Wrong tone marks

The image is too small for the marks to be told apart. Photograph from closer.

Capital letters lose their marks

The crop cut off the space above the line. Leave a margin above the text.

How to use Vietnamese OCR, step by step

1. Press "Choose images" or drag files onto the box.
2. Set the options if you need to; the defaults suit most uses.
3. Press "Extract text". The work happens on your device.
4. Save the result with its download button.

Is it safe to do this online?

With most online tools, "online" means your file is uploaded to a company's server, processed there and kept for a while before it is deleted. Here it is not. The page downloads the tool's code to your browser, and your file is read and processed inside the tab on your own device. It is never sent to TapToConvert or anyone else.

You can check this yourself: once the page and its engine have loaded, turn off Wi-Fi and the tool still works. That also means there is no queue, no daily limit and no file size cap set by a server; the only limit is the memory your browser gives a single tab.