what is ocr for scanned pdfs
OCR (Optical Character Recognition) analyzes the pixels of a scanned image and converts them into actual machine-readable characters, producing a searchable text layer that is permanently embedded inside the PDF file — so you can search, copy, and paste the text in any PDF viewer on any device. Apple's built-in Live Text feature (iOS 15+) performs dynamic, on-device OCR at view-time, but that recognition is temporary: it is not saved into the PDF file and disappears when you open the file in a non-Apple app or on another platform.
Resposta curta
OCR (Optical Character Recognition) analyzes the pixels of a scanned image and converts them into actual machine-readable characters, producing a searchable text layer that is permanently embedded inside the PDF file — so you can search, copy, and paste the text in any PDF viewer on any device. Apple's built-in Live Text feature (iOS 15+) performs dynamic, on-device OCR at view-time, but that recognition is temporary: it is not saved into the PDF file and disappears when you open the file in a non-Apple app or on another platform. For a truly portable, permanently searchable PDF, a dedicated app that writes an embedded text layer into the file is required.
O ScanTo Pro faz exatamente isso no seu iPhone: digitaliza para um PDF limpo, executa OCR no dispositivo e pode bloquear ficheiros com Face ID — uma aplicação de pagamento único, sem subscrição. Consulte a página na App Store para ver as funcionalidades atuais.
O que verificar antes de escolher
- Embedded OCR text layer: saved into the file permanently, searchable on any device/OS
- Apple Live Text: on-device, private, real-time — but the text layer is NOT written into the PDF
- On-device OCR (e.g., Apple Vision / Core ML) keeps document images private; cloud OCR sends images to external servers
- OCR enables accessibility: screen readers and assistive technology can read the text aloud
- OCR accuracy depends on scan quality — sharp, high-contrast scans produce far fewer recognition errors
Um processo de decisão prático
- Embedded OCR text layer: saved into the file permanently, searchable on any device/OS.
- Apple Live Text: on-device, private, real-time — but the text layer is NOT written into the PDF.
- On-device OCR (e.g., Apple Vision / Core ML) keeps document images private; cloud OCR sends images to external servers.
- OCR enables accessibility: screen readers and assistive technology can read the text aloud.
- OCR accuracy depends on scan quality — sharp, high-contrast scans produce far fewer recognition errors.
Comparação rápida
| Necessidade | O que verificar | Porque importa |
|---|---|---|
| Modelo de preços | Verifique se as funcionalidades úteis exigem subscrição, um desbloqueio único, ou nenhum dos dois. | A app mais barata no primeiro dia pode não ser a mais barata ao fim de um ano. |
| Modelo de privacidade | Prefira o processamento no dispositivo quando o conteúdo é sensível. | Documentos privados, currículos, dados de estudo e conteúdos familiares merecem um tratamento cuidadoso. |
| Exportação / dependência | Confirme os formatos de ficheiro, a partilha, as cópias de segurança e os controlos de eliminação. | Uma boa app deve ajudá-lo a concluir a tarefa, não prender o seu trabalho. |
Onde o ScanTo Pro se encaixa
ScanTo Pro is a strong fit when you want private, on-device scanning without a subscription.
Pague uma vezSem subscriçãoNo dispositivo
Este é um guia de compra escrito pelo editor da app. Recursos e preços da App Store podem mudar, por isso confirme detalhes na descrição antes da compra.
Perguntas frequentes
Can I copy text from a scanned PDF on iPhone without an OCR app?
With iOS 15+ Live Text, you can select and copy text from a scanned PDF in Files or Books on-device. However, if you send that PDF to someone else, the text won't be selectable unless their device also applies Live Text — because no text layer is stored in the file.
What languages does on-device OCR support on iPhone?
Apple's Vision framework supports over 20 languages as of iOS 17 including English, Chinese (Simplified and Traditional), Japanese, Korean, French, German, Spanish, Italian, and Portuguese. Coverage continues to expand with each iOS release.
Is cloud OCR more accurate than on-device OCR?
Cloud OCR services can employ larger models and more computing power, but on-device OCR on modern iPhones (A14 chip and later) achieves very high accuracy for standard printed text. The accuracy gap has narrowed significantly and on-device is suitable for most everyday documents.