Runs in your browser with pdf.js and pdf-lib
PDF Enhancer Online — make faded scans easier to read
Whiten yellowed paper, darken faint text and sharpen soft edges on scanned PDF pages. Every page shows the result as you move the sliders, so you know what you'll get before you save.
- PDF files aren't uploaded to our server
- Live preview on every page
- Whitens yellowed paper
- Free, no account
Clean up a scanned PDF, page by page
Add a PDF, pick a starting point, fine-tune while watching your pages, then save.
Drop your PDF here
or browse — one PDF, any number of pages
Page 1
Updates as you change the settings. Tap a page to check it full size.
Your pages
Pages update as you change the settings. Click one to check it full size.
How enhancement actually works
A bad scan has several problems, so there are several controls
Gray paper, faint ink and soft edges each need a different fix. One "make it better" button can't know which your scan has; your eyes on the preview can.
What happens to your pages
Each page you choose is drawn as a picture at the resolution you pick, cleaned with your settings, and put back into the same PDF at its original size and position. Pages you leave out, bookmarks and the document title stay as they were, and links and form fields stay on top of the cleaned page.
Because an enhanced page becomes a picture, its text can no longer be selected or searched. That is the trade-off of any tool that changes how a page looks pixel by pixel. pdf.js and pdf-lib do the work in your browser tab, so your PDF isn't uploaded to our server.
The controls, and what each one fixes
Clean background
Finds the paper tone on each page and turns it white, so a yellowed or gray scan looks like clean paper.
Brightness and contrast
Brightness lightens or darkens the whole page; contrast pushes faint ink darker and light areas lighter.
Sharpness
Strengthens the edges of letters that are already there. It can't recover detail a blurred photo never captured.
Grayscale or black and white
Grayscale removes color casts. Black and white picks the cut-off between ink and paper for each page on its own.
How to enhance a scanned PDF in four steps
Start from Balanced, then change one slider at a time while you watch the pages.
Add your PDF
Drop a PDF onto the upload area, or click Select PDF. Every page appears with the Balanced settings already applied.
Switch the pages to Original at any time to compare.
Pick a starting point and fine-tune
- Light, Balanced or Strong sets all four sliders at once.
- Move any slider and the pages update; the preset shows Custom.
- Grayscale or Black and white for text-only pages.
Check the details full size
Click a page to open it full size. It is drawn at the resolution it will be saved at, so small print and sharpening look exactly as they will in the file.
Choose Pages… or Pick below to enhance only some pages.
Enhance and download
Click Enhance PDF. The result shows the new file size and a preview drawn from the saved file. Rename it if you like, and download.
What enhancing a faded scan can do
One low-contrast scanned page, before and after.
Which settings to use for your scan
A starting point for common files. Check the result full size before you download.
| Scan | The problem | Settings to try |
|---|---|---|
| Old letter or yellowed book page | Paper has turned yellow or brown; ink has faded. | Balanced, Clean background 80 or more; Grayscale if the color doesn't matter. |
| Photocopy of a photocopy | Gray background, washed-out letters. | Strong, or Black and white for text-only pages. |
| Phone photo of a document | Uneven light, gray paper, soft edges. | Balanced, Sharpness 40 to 60; check one page full size. |
| Receipts and invoices for records | Thermal print fades to light gray. | Strong with Contrast 40 or more, Grayscale, 200 dpi. |
| Drawing or plan with fine lines | Thin lines blur into the paper. | Light, Sharpness 30 to 50, 300 dpi. |
| Report with photos and charts | Text pages are faded; photo pages look fine. | Pages… with only the text pages; Keep colors. |
| Sheet music for a tablet | Staff lines and notes are faint on gray paper. | Black and white, Sharpness 30. |
Settings in numbers
What each setting actually does
No hidden steps: these are the exact values behind the presets and sliders.
The presets
Clean background, brightness, contrast and sharpness: Light 30, 0, 10, 20, Balanced 60, 0, 20, 35, Strong 90, 5, 35, 55. None sets everything to 0.
Clean background
Finds the most common light tone on each page, the paper, and scales it toward white. At 100 the paper becomes pure white; dark ink changes much less. Pages without a clear paper tone, like full-page photos, are left alone.
Brightness and contrast
Brightness adds or removes up to 50 of 255 levels on every pixel. Contrast from -50 to 50 pulls tones together or apart around mid-gray.
Sharpness
An edge-strengthening filter one pixel wide at the saved resolution. 0 is off; above about 60, white halos and speckle can appear around letters.
Black and white
Each page gets its own cut-off point between ink and paper, worked out from that page's tones (Otsu's method), so a light page and a dark page both come out clean.
Resolution and file size
Enhanced pages are saved as JPEG pictures at 90% quality. An A4 page has about 2.2 million pixels at 150 dpi, 3.9 million at 200 dpi and 8.7 million at 300 dpi, so higher settings make larger files.
When the result isn't what you expected
Identify the problem, then use the matching fix.
Light text or pencil disappears
Clean background or brightness is high enough to turn faint marks white along with the paper.
Lower Clean background, set Brightness to 0 or below, and raise Contrast instead.
White halos around letters
Sharpness is too high for this scan.
Open a page full size, then lower Sharpness until the halos go.
Black and white loses parts of a photo
Black and white keeps only two tones, which suits text but not pictures.
Use Grayscale for that page, or enhance the text pages and photo pages separately with Pages….
The file got bigger
Enhanced pages are saved as new pictures, which often weigh more than the original scan or text.
Try 150 dpi, enhance only the pages that need it, or run the result through Compress PDF.
Text can't be selected any more
Each enhanced page is saved as a picture.
Enhance only the scanned pages with Pages… and leave pages with real text out.
"Pages to enhance" shows an error
A number is past the last page, a range is reversed, or there's a typo.
Follow the message under the box. Use forms like 1-3, 7 or 10- for "to the end".
A password-protected PDF won't open
Encrypted PDFs can't be rewritten by the in-browser PDF libraries.
Remove the password with Unlock PDF, then add the unlocked copy.
Clear pages without overdoing it
A working order that gets a readable file on the first try.
Start with Balanced
It suits most office scans. Go to Strong only if the paper still looks gray or the ink still looks faint.
Fix the paper first
Raise Clean background before touching Brightness. Whitening the paper often makes the text look darker on its own.
Judge sharpness full size
Small previews make sharpening look stronger than it is. Open the page with the smallest print and zoom to 200%.
Look at more than one page
Scan quality changes through a document. Scroll the pages before you save, especially the first and last.
Leave text pages out
Pages typed on a computer don't need enhancing, and keeping them out keeps their text searchable.
Keep the original
Detail turned white can't be brought back from the enhanced file. Keep the original scan as your master copy.
Common questions about enhancing PDFs
If something's not covered here, the troubleshooting section above likely has it.
Does this tool upload my PDF to a server?
No. The previews and the enhancing both run in your browser with pdf.js and pdf-lib. Your PDF is read on your device and is not uploaded to the AllInOneTools server.
Will the text in my PDF still be selectable?
Not on the pages you enhance. Each enhanced page is saved as a cleaned-up picture, so its text can't be selected or searched. Pages you leave out keep their text, and links and form fields stay on top of enhanced pages and keep working.
Which setting should I start with?
Balanced suits most scans. If the paper still looks gray or the ink faint, try Strong. For pages with only text, Black and white often gives the cleanest result. Open a page full size to check before you save.
What does Clean background do?
It finds the paper tone on each page, the most common light shade, and turns it white, so yellowed or gray paper looks clean. Because it measures every page separately, a darker page and a lighter page in the same file both come out evenly.
Why is the enhanced PDF bigger than the original?
Enhanced pages are saved as new pictures at the resolution you pick, and pictures usually weigh more than the original scan or text. Choose 150 dpi, enhance only the pages that need it, or compress the result afterwards.
Can it fix a blurry or out-of-focus scan?
Only a little. Sharpness strengthens edges that are already in the scan, which makes slightly soft text look crisper. It can't recover detail the scanner or camera never captured, and too much sharpening adds halos.
Can I enhance only some pages?
Yes. Choose Pages… and type numbers or ranges such as 1-3, 7, or choose Pick below and tap Enhance on the pages you want. Every other page is left exactly as it was.