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OCR guide

How to Improve OCR Accuracy for Scanned Documents

Practical image-quality, language and verification techniques for more accurate OCR on invoices, forms and procurement documents.

By FormatForge2026-07-218 min read

Quick summary

Practical image-quality, language and verification techniques for more accurate OCR on invoices, forms and procurement documents. This guide gives you a clear, practical explanation before you use the related online tool.

1

Use enough resolution

Text should be clearly distinguishable without excessive enlargement. Around 200–300 DPI is a useful target for many printed business documents.

2

Straighten and crop

Skewed text makes line detection harder. Rotate the page correctly and remove large borders, backgrounds or unrelated objects.

3

Improve contrast

Faint grey text, shadows and coloured paper reduce separation between characters and background. A clean, evenly lit scan usually performs better than a phone photo taken at an angle.

4

Choose the minimum language set

An unrelated language model can introduce alternative character predictions. Use one language whenever possible.

5

Watch high-risk characters

Common confusions include O and 0, I and 1, S and 5, decimal commas and points, and similar characters across scripts. Verify codes and financial values character by character.

6

Use confidence intelligently

Confidence can prioritise review but should not be treated as a guarantee. A high-confidence total can still be wrong when the source is ambiguous.

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Frequently asked questions

Is 300 DPI always required?

No, but it is a practical target for small printed text. Clear lower-resolution images may also work.

Does PDF compression hurt OCR?

Aggressive image compression can blur characters and reduce accuracy.

Can OCR fix a blurry photo?

It cannot recover details that are not present. Rescan the document when possible.

Why are tables sometimes misaligned?

OCR recognises text and layout imperfectly; complex borders and merged cells can disrupt reading order.

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