Open the app — PDF Border Cleaner
Lay a book face down on a copier and everything around it comes out pitch black.
The lid can’t close, so the empty space gets photographed along with the page.
Material from libraries usually arrives in exactly this state.
On screen you shrug it off, but printing is another matter.
Filling in those black borders drains toner alarmingly fast, and the paper comes out damp.
Print one 100-page document and you start resenting the cost of toner.
This tool finds only the dark area around the edges and turns it white.
Text and photographs inside the page are left alone.
How to Use
Basic Steps
- Drag a PDF file in or click to upload it.
- Check the original and result side by side in the preview.
- Adjust the settings if needed.
- Click [Clean Borders & Download].
The preview is split left and right, so you can see immediately what changes.
Changing a setting updates the preview, so try a few values before deciding.
Darkness Threshold
Decides how dark something has to be to count as border. From 30 to 150, default 80.
| Situation | What to do |
|---|---|
| Border isn’t fully removed | Raise it (treats lighter grey as border too) |
| Body text is disappearing | Lower it (only very dark areas count as border) |
The right value depends on the scan. Watching the preview while you adjust is the fastest route.
Border Margin
Decides how much further inward to push after removing the border. From 0 to 30 pixels, default 5.
Between the black area and the white paper there is usually a blurred boundary.
Erase exactly up to the black and that grey rim stays behind, looking untidy.
A little margin sweeps that away too.
Push it too far and the edges of your text can get cut, so start at 5.
Rendering Scale
Decides how large the page is drawn while processing. From 1× to 4×, default 2×.
Higher scales give a more precise result but take longer and produce bigger files.
Use 3× or more for material with small type; leave the default for ordinary documents.
Convert to Grayscale
An option to save the file in black and white instead of color.
Printing a text-only document in color burns color toner just to make black.
Convert to grayscale and only black toner is used, which saves that much.
Good to Know
How Only the Border Is Picked Out
The key is that it starts at the edges and spreads inward.
Pixels along the four sides are examined first; anything darker than the threshold is marked as border, and the marking spreads to dark pixels connected to it.
It seeps inward like water and stops when it meets something bright.
Because of this, a black photograph or heavy lettering in the middle of the page is safe.
If it isn’t connected to the edge, it is never touched no matter how dark it is.
Simply turning “every dark pixel” white would have destroyed the photographs too.
Material It Suits
- Pages scanned by laying an open book on a copier
- Older scans received from libraries and institutions
- Anything with a black band around the edge
It is not suited to material whose background is meant to be dark — black-background slides, for instance. The whole background would be treated as border.
Notes
- Pages are redrawn as images, so text search is lost. Keep the original if you need to search it.
- Large files or high scales take a long time.
- All processing happens in the browser and no file is sent to a server.
Pairs Well With
For material scanned as open spreads, splitting it first with the PDF Left-Right Splitter and then cleaning the borders gives the tidiest result.
Open the app — PDF Border Cleaner