PDF Scan Enhancer
Local Processing (Offline Capable)Enhance scanned PDFs and smartphone photos. Removes uneven shadows, flattens yellowed backgrounds, preserves red stamps, and sharpens text.
How this tool works (no sign-up needed)
- Upload your file above. Each tool shows whether it runs Local (in your browser) or Cloud (encrypted servers).
- Adjust options, then click the Run / Convert / Process button.
- Wait for progress, then download the result. Use Next tools to continue.
If buttons are not visible, enable JavaScript — the interactive workspace loads in your browser.
Free · 100% Local Scanner EngineCamScanner-grade paper flattening: removes mobile camera shadows, boosts contrast, and sharpens text.
Enhancement is for readability only (scanning, archiving, printing). Do not use it to forge, alter, or misrepresent original documents.
Supports application/pdf,.pdf,image/png,image/jpeg,image/webp,.png,.jpg,.jpeg,.webp
Local — your file is processed in your browser and not uploaded to us. No account needed.
What is it?PDF Scan Enhancer is a PDFLean AI document tool: Enhance scanned PDFs and smartphone photos.
TL;DR: Enhance scanned PDFs and smartphone photos. Processing runs entirely in your browser — your file is never uploaded; runs offline using client-side integral image adaptive thresholding.
About this tool
A focused utility built for a single recurring document task. Enhance scanned PDFs and smartphone photos. Removes uneven shadows, flattens yellowed backgrounds, preserves red stamps, and sharpens text. Processing runs locally in your browser's memory — the document is never transmitted, and closing the tab clears it completely. The workflow is deliberately short: load the file, choose the options on the page, run the operation, and save the result. Every choice is applied before the file is written, so re-running with different settings takes seconds. Output is an enhanced PDF; PNG, JPG, and WEBP photos are accepted as input. Practical limits apply (see the on-page limits); it pairs well with the related tools linked beside this page when one step is not the whole job. Key facts — Processing: runs entirely in your browser, client-side; Access: free with no account required; File limits: see the on-page limits; Privacy: the file never leaves the device.
How to use
Drop your PDF document or photo (PNG/JPG/WEBP) into the workspace
Compare before and after in real-time preview, selecting between "Magic B&W", "Color Document", "Clean Grayscale", or "Text Sharpen"
Navigate across multi-page PDFs using the pagination controls
Click "Enhance & Export PDF" to render enhanced high-resolution pages
Download your crisp scanner-quality PDF
FAQ
Can this remove harsh shadows cast by my phone or hand when taking a photo?
Yes. Our engine uses the Bradley-Roth adaptive thresholding algorithm with integral images. It dynamically estimates local illumination fields across sliding windows, cleanly separating foreground ink strokes from ambient shadows.
Does the Color Document preset erase colored stamps or logos?
No. The Color Document preset isolates luminance from chromatic channels. It normalizes paper backgrounds to pure white while preserving the original color vibrancy of official red stamps, signatures, and charts.
Does image enhancement sharpen blurry or low-contrast text?
Yes. Adaptive contrast stretching and high-frequency edge sharpening turn gray, blurry strokes into crisp, solid dark text for easier reading and better OCR.
How fast is enhancement across multi-page scans, and will the browser lag?
Processing runs entirely in your browser without uploading files. Powered by Bradley-Roth integral images, Web Worker background threads, and Canvas rendering, it handles multi-page documents smoothly with a progress bar while keeping memory stable.
Can yellowed, aged, or stained paper backgrounds be purified to pure white?
Yes. The "Magic B&W" or "Clean Grayscale" preset estimates background paper tint and normalizes local illumination, eliminating shadows and yellowing to restore a clean, uniform white background.