OCR: how to extract text from scanned images
Optical character recognition (OCR) detects characters in a photo or scanned page and turns them into text that software can search or copy. The result is a software prediction, not a verified transcript. ConverteArq does not currently provide OCR; this guide explains the process and its limits.
When OCR is useful
OCR can help make a scanned document searchable, copy text from a photo, or prepare content for later editing. A digital PDF may already contain selectable text and may not need OCR.
Recognition does not verify whether a name, date, amount, or instruction is correct. Keep the source page and compare important passages before relying on the output.
How to extract text from an image
Choose an OCR service or app and check its supported formats and languages. Submit a clear image or scanned PDF within the provider’s limits, select the correct language if available, then export or copy the recognized text. The steps and features vary by product and version.
Review the result against the original, especially names, dates, amounts, accents, table columns, handwriting, and low-contrast text.
Prepare the scan and protect the document
Use sharp focus, even lighting, and straight text lines. Avoid shadows, glare, blur, and cropped letters or table edges. Tesseract’s documentation says its engine works best at 300 dpi or above; that is guidance for Tesseract, not a universal requirement for every OCR tool or camera. Follow the receiving organization’s specifications.
Before uploading a document, read the provider’s current rules for processing, storage, retention, and access. Sensitive identity, financial, health, or business documents may require an approved local workflow.
Frequently asked questions
Do all OCR tools require 300 dpi?
No. Tesseract documents 300 dpi or above as guidance for its own engine. Other software, cameras, and receiving organizations can have different requirements.
Does OCR read handwriting?
Some systems support handwriting, but results depend on the script, language, handwriting, image quality, model, and product. Check the result against the page.
Does a searchable PDF guarantee accurate text?
No. Searchable text can still contain recognition errors or incorrect reading order. Verify important details in the original.
Technical references
Related guide
For tips on taking a clear source image, read how to scan documents with a phone.