OCR accuracy depends heavily on source document quality. These tips help you get the best text extraction from scanned PDFs.
Tip 1: Scan at 300 DPI Minimum
Scan resolution directly affects OCR accuracy. 300 DPI is the minimum for reliable results. 400 DPI is better for small text or less-than-perfect documents. Higher DPI produces larger files but significantly better OCR accuracy for challenging documents.
Tip 2: Deskew Before OCR
Slightly crooked scans (common when documents aren't perfectly aligned on the scanner) reduce OCR accuracy. Use a deskew tool (or the deskew option in your scanner software) to straighten pages before OCR processing.
Tip 3: Select the Correct Language
Always select the document's actual language for OCR. Using the wrong language model (English OCR on a French document) dramatically reduces accuracy. For multilingual documents, select the primary language.
Tip 4: Create Searchable PDF Instead of Text-Only
When you need to keep the document's visual appearance (for contracts, forms, official documents), create a searchable PDF rather than extracting to text. Searchable PDF preserves the original appearance while adding text search capability.
Tip 5: Always Proofread OCR Output
Even excellent OCR makes occasional errors — particularly with unusual characters, proper nouns, and numbers (1/l, 0/O confusion). Always proofread OCR output before using in important documents. Pay special attention to names, dates, and numbers.
Conclusion
Better scans produce better OCR. Scan at 300+ DPI, deskew first, select the correct language, and always proofread output. Extract text free at toolhq.app/tools/ocr-pdf (coming soon).
अक्सर पूछे जाने वाले सवाल
Why is my OCR output full of errors?
Common causes: scan resolution below 300 DPI, crooked/skewed pages, low contrast between text and background, or wrong language selected. Improve scan quality and rescan for better results.
Can OCR extract text from tables?
Yes. Advanced OCR preserves table structure. Results vary — simple bordered tables extract well; complex merged-cell tables may require manual correction.
Does OCR work on PDF forms?
Yes. OCR extracts text from scanned PDF forms including filled-in values. For interactive PDF forms (not scanned), text is already selectable without OCR.
Is OCR PDF free on ToolHQ?
Yes, completely free with no registration. Coming soon at toolhq.app/tools/ocr-pdf.
Can I OCR a multi-page PDF?
Yes. All pages are processed simultaneously. Each page is OCR'd and the text is added to the searchable PDF or combined into a single text file.
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