Compress Scanned Documents
Scanners and phone scanning apps produce large colour images of what is usually dark text on white paper. This tool cleans the page (grey paper becomes white, text gets darker), converts it to greyscale or pure black and white, limits it to 300, 200 or 150 DPI for an A4 or Letter sheet and sharpens the lettering, so a scan of several megabytes typically drops to a few hundred KB and stays readable.
- Processed locally
- No upload, no wait
- No sign-up
- No watermark
Drop images here
or choose files · paste with Ctrl/⌘ V
JPG, PNG, WebP, HEIC, AVIF, GIF, TIFF, SVG, RAW, PSD, JXL, BMP, ICO and more
How to use Scan Compressor
- 1
Drop your images, choose files, or paste from the clipboard.
- 2
Adjust the options. The preview updates as you change them.
- 3
Click Compress. Files are processed on your device.
- 4
Download each result or everything as a ZIP.
Why use Aback Images for scan compressor
Cleaner pages
Levels are stretched so grey or yellowed paper turns white and faded text gets darker, which also makes the file compress better.
Colour, greyscale or 1-bit
Text pages rarely need colour. Greyscale roughly thirds the data before compression; 1-bit PNG is smallest of all for typed text.
Sized for the page
300, 200 or 150 DPI for an A4 or Letter sheet, with the DPI recorded, so the file prints at the right size. Smaller scans are never enlarged.
Processed on your device
Your images are decoded, edited and encoded inside this browser tab by Web Workers. Nothing is uploaded to a server.
About Scan Compressor
Limitations
- Pages with photos, colour charts or highlighter lose information in greyscale and black and white; keep those in colour.
- Very faint pencil can vanish in black and white mode; raise the ink threshold or use greyscale.
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Frequently asked questions
Which DPI should I choose?
200 DPI keeps ordinary text clearly readable and suits most upload portals. Use 300 DPI for small print, signatures or pages that may be printed again, and 150 DPI when the file limit is very tight.
When should I use black and white?
For typed or printed text with no photos, 1-bit black and white saved as PNG is the smallest option and very sharp. Stamps, highlighter and photos need greyscale or colour.
Can I make a PDF?
Yes: choose PDF under Save as and each scan becomes a one-page PDF. To combine pages into one document, compress them here as JPG and then use Image to PDF.
Are my images uploaded anywhere?
No. Processing happens inside your browser with WebAssembly and Web Workers. The site only downloads the app code and codecs; your files never leave your device. You can confirm this with the live upload counter on the tool, or in your browser's network panel.
Can I process many files at once?
Yes. Drop a whole selection or folder. Files are processed in parallel on several worker threads, each result can be downloaded on its own, and everything can be saved as one ZIP.
Is it free? Is there a file limit or watermark?
It is free with no account, no watermark and no daily limit. The only limit is your device's memory: very large images (over roughly 100 megapixels) may be refused to keep the tab from crashing.