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NyankoTools
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Document Scan Filter: Remove Shadows and Clean Up Photos

Pick a photo of a document and get a scan-style image: uneven lighting and shadows are removed, the paper turns white, and the text gets sharper. Choose color, grayscale, or pure black & white and compare before and after. For general brightness and saturation tweaks, use Image Filter; to cut away the background first, try Image Cropper.

🔒 Runs in your browser · Your data is never sent to a server

You can also drag and drop an image file here

Presets
Color mode
Output format

PNG is lossless, so the quality setting has no effect

How to use

  1. Choose a photo of your document (drag & drop also works).
  2. Pick a preset, or adjust "Color mode", "Shadow / uneven light removal", and "Paper whiteness / text darkness".
  3. Compare the before and after previews, then choose an output format.
  4. Click "Download" to save the result.

Notes

  • Your image is processed only in your browser and is never uploaded, so contracts, IDs, and receipts stay private.
  • The saved file is at most 3,000 px on the long edge. Larger images are scaled down while keeping the aspect ratio.
  • Shadow removal assumes the paper is mostly bright across the photo. If the paper fills only a small part of the frame, or the whole page is dark, the result can look unnatural.
  • Pure black & white makes text easy to read, but photos, faint print, and colored lines can disappear. Try grayscale or adjust the "Threshold" manually.
  • Skew and perspective distortion are not corrected. Crop the image first if needed.
  • Exif metadata such as shooting location is not carried over, because the image is re-encoded.

Glossary

Binarization

Reducing an image to just black and white. Pixels darker than the threshold become black and the rest become white, which looks like a photocopy and keeps files small.

Otsu's method

A way to pick the threshold automatically from the brightness distribution so that black and white are separated cleanly. It is used when the automatic threshold option is on.

Shadow removal

Estimates how dark the paper is in each area and brightens it so the whole page ends up the same white.

FAQ

Is my photo uploaded anywhere?

No. All processing happens in your browser with Canvas, and the image is never sent to a server, so photos of contracts or IDs stay on your device.

Shadows remain or the paper looks gray. What can I do?

Raise "Shadow / uneven light removal" and nudge "Paper whiteness / text darkness" up. The paper color can only be estimated well when paper fills most of the photo, so cropping to the document first gives cleaner results.

Text looks broken in black & white mode. How do I fix it?

Turn off the automatic threshold and raise the threshold so fainter text stays black. If that is not enough, save as grayscale instead.

Can it handle large photos?

It accepts files up to about 40 megapixels and 25 MB. When saving, the long edge is scaled down to at most 3,000 px, which is plenty to read document text. Use a different tool if you need the original size.

How do I turn the result into a PDF?

Save the PNG or JPEG and load it into an image-to-PDF converter to build a PDF of your document.

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