用强有力的密码保护和加密保护你的PDF。
在不影响画质的情况下减少文件大小。
You compressed a PDF to save space, but now the text is blurry, images are blocky, and the document looks unprofessional. Over‑compression destroys fine details, introduces 8×8 JPEG artifacts, and creates fuzzy edges. Our AI‑powered tool reverses this damage: removes blocks, sharpens edges, and recovers lost detail – all without blowing up the file size. Perfect for emails, archived documents, and any PDF that was squashed too much. Free trial, no signup required.
Did you know? JPEG compression below quality 50% discards over 90% of high‑frequency image data. Our AI reconstructs plausible detail from the remaining low‑frequency information.
Visible grid patterns around text and edges. Our deblocking filter removes them.
Sharp edges become fuzzy. AI sharpening restores crispness.
Fuzzy halos around characters. Our denoiser removes them.
Subtle textures disappear. Detail synthesis adds back realistic grain.
Bonus – downsampling blur: Some compression also reduces DPI, causing overall softness. AI upscaling can restore resolution.
Upload your compressed PDF – The tool analyses artifacts, blur, and blockiness.
Select restoration strength – Light (mild artifacts), Medium (recommended), or Strong (heavy damage).
Apply AI restoration – Deblocking, sharpening, denoising, and optional super‑resolution. Preview side‑by‑side.
Download the restored PDF – Sharper, cleaner, and more readable.
Pro Tip: If your PDF was also downsampled (low DPI), enable “Upscale to 300 DPI” after deblocking for print‑ready results.
All techniques are applied adaptively – only to damaged areas.
A 10‑page PDF was compressed at JPEG quality 30% for email. The resulting file had visible 8×8 blocks around all text, fuzzy letter shapes, and grainy backgrounds. After restoration (deblock + sharpen + denoise), the blocks disappeared, text became crisp, and OCR accuracy jumped from 64% to 97%. The final file was only 15% larger than the compressed original – still email‑friendly.
Try it yourself – upload any compressed PDF and see the difference.
Many people fear that restoring quality will balloon file size. In practice:
For typical business documents, the restored PDF stays well within email limits (25 MB).
Tip: Use “Balanced Compression” after restoration to keep the final size even smaller.
Yes, to a large extent. While you cannot recover lost information perfectly, our AI models trained on millions of compressed‑original pairs can reconstruct sharp edges, remove block artifacts, and restore fine detail. The result is dramatically better than the compressed original – often indistinguishable from a lightly compressed file.
We fix JPEG block artifacts (8×8 squares), mosquito noise (fuzzy halos around text), blur from downsampling, colour bleeding, and overall softness. Our tool also repairs PDFs that were over‑compressed for web use.
No. Artifact removal and sharpening add very little size (usually under 10%). In many cases, removing JPEG blocks actually helps compression, so the final file size may be similar or only slightly larger. If you also upscale DPI, size will increase – but that is optional.
Yes. Repeated compression compounds artifacts, but our AI can handle multiple generations. Use the “Aggressive” restoration mode for very damaged files – it applies stronger deblocking and sharpening.
Absolutely. We apply edge‑preserving sharpening to text, and deblocking + detail synthesis to images. Both benefit significantly from restoration.
Yes. TLS 1.3 encryption, auto‑deletion within 24 hours. Offline version available for sensitive documents.
The online tool processes one file at a time. For batch processing, our desktop application (paid) handles folders.
Restoration improves visual quality but does not add a text layer. If your PDF originally had no text layer (e.g., scanned), run OCR after restoration for best results.
Upload your damaged PDF and let AI remove artifacts and sharpen text – free trial, no signup.
增强PDF通过调整分辨率、锐化文本边缘以及增加前景和背景元素之间的对比度来提高视觉清晰度。此过程对于扫描文档、模糊文本或褪色文件特别有用。
多种因素可能降低PDF文档的可读性。低分辨率扫描、过度压缩、不正确的导出设置和相机拍摄的文档都可能导致模糊或降低对比度。
现代PDF增强工具应用多种处理技术来提高可读性。
PDF增强算法通过分析像素密度和灰度分布来工作。对比度调整增加了文本和背景之间的差异，而锐化滤波器重建模糊边缘。当与OCR准备结合时，增强显著提高了机器可读性。
在PDF增强指南中探索完整的工具集合。