How to Fix Common OCR Errors

Introduction

Identify and correct typical OCR mistakes: character confusion, spacing, and encoding issues. This guide assumes you have a basic understanding of PDF files and builds on that knowledge with more detailed techniques and real-world scenarios. Whether you're using PDFly's free online tools or building your own workflow, this guide covers everything you need to know about how to fix common ocr errors.

Understanding OCR

OCR (Optical Character Recognition) transforms scanned documents and images into searchable, selectable text. This technology is essential for working with scanned paperwork, making it searchable, editable, and accessible. Modern OCR engines achieve 99%+ accuracy on quality scans.

Key Concepts You Need to Know

OCR accuracy depends on scan quality — 300 DPI is the recommended minimum
Pre-processing (deskew, despeckle, binarize) dramatically improves OCR results
Multi-language OCR requires language packs and script detection
OCR creates a text layer over the image, preserving the original appearance
AI-enhanced OCR achieves higher accuracy on handwriting and low-quality scans

1

Upload Your Scanned PDF

Open PDFly's OCR tool and upload your scanned document or image-based PDF.

2

Select Language

Choose the document's language for accurate text recognition. Multi-language is supported.

3

Run OCR Processing

Click the OCR button. The tool processes each page, creating a searchable text layer.

4

Download Searchable PDF

Download the OCR-processed PDF. You can now search, select, and copy text from the document.

Tips & Best Practices

Pre-process scans with deskewing and despeckling for best OCR accuracy

Use 300 DPI minimum for OCR — lower resolutions significantly reduce accuracy

Choose the correct language pack for documents in non-English languages

Review OCR output for common errors (0/O, 1/l/I, rn/m confusion)

Use batch OCR for large document sets to save time

Common Mistakes to Avoid

Avoid These Common Pitfalls

Low-resolution scans produce poor OCR results with many errors
Not selecting the correct language causes character recognition failures
Skipping pre-processing steps significantly reduces accuracy
Handwritten text is still challenging for most OCR engines
Multi-column layouts may produce jumbled text without proper handling

Quality Checklist

0 / 5 completed

Scan quality is at least 300 DPI The correct language pack is selected Pre-processing (deskew, despeckle) has been applied OCR output has been reviewed for common errors The searchable PDF has been tested for text selection

Key Takeaways

300 DPI minimum scan quality is essential for accurate OCR

Pre-processing (deskew, despeckle) dramatically improves results

OCR creates a searchable text layer without changing the document appearance

Frequently Asked Questions

OCR (Optical Character Recognition) converts text in images and scanned documents into searchable, selectable text. Without OCR, scanned PDFs are just images — you can't search, copy, or edit the text.

Modern OCR engines achieve 95-99% accuracy on quality scans (300 DPI or higher). Accuracy decreases with poor scan quality, unusual fonts, handwriting, or complex layouts.

Yes, PDFly's OCR supports 100+ languages. You can select the document's language for optimal accuracy, and multi-language documents are supported.

No, OCR adds an invisible text layer over the original image. The visual appearance remains identical — you can now search, select, and copy text, but the document looks the same.

How to Fix Common OCR Errors

Introduction

Understanding OCR

Key Concepts You Need to Know