Secure your PDF with strong password protection and encryption.
Reduce file size without losing quality.
Extracting text from scanned PDFs is frustrating when the original scan is crooked, dusty, low‑contrast, or low‑resolution. Our AI‑powered pre‑processor cleans and optimises your scans for near‑perfect OCR and text extraction. Apply deskew, despeckle, contrast normalisation, background flattening, and optional DPI upscaling – all in one click. Perfect for legal discovery, invoice processing, academic research, and digitising archives. No software installation required – your files are processed securely and automatically deleted.
Did you know? Raw OCR accuracy on a 150 DPI, skewed, speckled scan can be as low as 60%. After our enhancement (deskew + despeckle + upscale to 300 DPI), accuracy typically exceeds 96% on the same document.
Cropped baselines confuse OCR, turning "rn" into "m". Deskew corrects this.
Dust and scratches create phantom punctuation and characters. Despeckle removes them.
Light grey text on grey background fails to trigger character detection. Contrast normalisation darkens text and whitens background.
Small characters become pixelated; OCR cannot distinguish fine features. Upscaling to 300 DPI solves this.
Bonus issue – bleed‑through: Text from the reverse side of a page adds ghost letters. Our bleed‑through removal isolates the front side.
Upload your scanned PDF – Our system automatically analyses skew, DPI, noise, and contrast.
Enable OCR‑prep mode – Select "Text Extraction" preset. It applies deskew, despeckle, contrast optimisation, and optional upscale to 300 DPI.
Preview the enhanced document – Check that text is straight, dark, and background is uniform.
Download the prepared PDF – Then run your favourite OCR tool (Tesseract, Adobe, ABBYY, or our online OCR) on the enhanced file.
Pro Tip: For mixed documents (text + images), use "Text‑only sharpening" after upscaling. This boosts character edges without affecting photos.
All steps are applied automatically in the "Text Extraction" preset. You can adjust individual strengths in advanced mode.
Our prepared PDFs work seamlessly with Tesseract, Adobe Acrobat OCR, ABBYY FineReader, Google Cloud Vision OCR, Microsoft Read API, and any custom OCR pipeline. We also offer our own free online OCR tool. After enhancement, run OCR and witness accuracy improvements of 30‑50% compared to the raw scan.
Real‑world example: A financial firm processed 10,000 invoices using our pre‑processor then ABBYY OCR. Character‑error rate dropped from 8% to 1.2%, saving hundreds of hours of manual correction.
Basic cleaning (deskew, despeckle, contrast) adds very little size. Upscaling to 300 DPI will increase file size by 2‑3x, but it is often worth it for mission‑critical OCR. Use our "Balanced" compression to reduce overhead by up to 50% while preserving fine detail. For trial runs, you can upscale only one page to test accuracy before processing the whole document.
Tip: If file size is critical, keep the original DPI and only apply deskew + despeckle + contrast. You will still see a significant accuracy boost.
⚡ Need to adjust or standardise DPI without changing pixels?
Use our dedicated PDF DPI Changer to view, adjust, or unify the DPI metadata of embedded images. Perfect for pre‑press compliance, print workflow validation, and preparing files for commercial printing without altering visual quality.
Scanned PDFs are images, not machine‑encoded text. OCR engines struggle with skew, dust speckles, low contrast, low DPI, and background noise. Proper pre‑processing fixes these issues, boosting extraction accuracy by up to 40%.
All four steps matter, but deskew‑ing (straightening crooked pages) has the biggest impact. A tilted page can break line detection and merge characters. Next is upscaling to 300 DPI, then contrast normalisation, and finally despeckling.
Yes. Most OCR engines are trained on 300 DPI images. Low‑DPI input (150 DPI) gives the engine too few pixels to distinguish between similar characters ("rn" vs "m", "0" vs "O"). Upscaling to 300 DPI dramatically reduces these errors.
Absolutely. Our enhancement is content‑agnostic. It improves overall image quality without altering text geometry, so all fonts, sizes, and layouts remain unchanged – only the clarity improves.
The online version processes one file at a time. For batch preparation of hundreds of PDFs, use our desktop application or API. Contact us for enterprise pricing.
Basic cleaning (deskew, despeckle, contrast) adds little size. Upscaling to 300 DPI may increase size by 2‑3x, but our smart compression keeps it manageable. You can also keep the original resolution and only clean the image.
Yes. All uploads are encrypted with TLS 1.3 and automatically deleted within 24 hours. We never use your documents for training. An offline version is available for strict security requirements.
Yes, it works on all modern smartphones and tablets. Upload from cloud storage or local storage – processing runs in the cloud. Wi‑Fi recommended for large files.
Upload your scanned PDF, let AI clean and optimise it, then run OCR for near‑perfect text extraction.
Enhancing a PDF improves visual clarity by adjusting resolution, sharpening text edges, and increasing contrast between foreground and background elements. This process is particularly useful for scanned documents, blurry text, or faded paperwork.
Several factors may reduce the readability of a PDF document. Low-resolution scanning, aggressive compression, improper export settings, and camera-captured documents can all introduce blur or reduce contrast.
Modern PDF enhancement tools apply multiple processing techniques to improve readability.
PDF enhancement algorithms work by analyzing pixel density and grayscale distribution. Contrast adjustment increases the difference between text and background while sharpening filters reconstruct blurred edges. When combined with OCR preparation, enhancement dramatically improves machine readability.
Explore the full collection of tools in the PDF Enhancement Guide.