Straighten Scans
స్కాన్ పేజీలను నిటారుగా
Tilted scanned pages found and straightened, page by page. Nothing is uploaded.
వంకరగా స్కాన్ అయిన పేజీలను నిటారుగా చేయడం: మీ ఫోన్లోనే, ఏదీ అప్లోడ్ కాదు.
1 Your PDF
2 Check the pages
Choose a PDF: each page’s tilt is measured from its lines of text.
Pages
How to straighten a tilted scan
- Choose the PDF (or drop it on the box). Each page's tilt is measured at once, on your phone or computer.
- Every page shows before and after. Tilted scans are ticked to straighten, with the tilt found, such as "Tilted 1.5° clockwise".
- Look at each after picture. Untick a page to leave it, or set its tilt by hand with −0.1° and +0.1° (or type it); the after picture turns as you go.
- Tap Straighten, then download or share the PDF.
Everything happens in your browser: the PDF is never uploaded to ap7am or anywhere else. The new file keeps
your PDF's name, such as certificate-straight.pdf.
How the tilt is found
The page's ink is found (the paper evened out first, so a shadow does not count) and projected across the page at trial angles from 10° one way to 10° the other: at the page's own tilt every line of text falls into a few rows and the gaps between the lines are clean, so the rows differ most. The best angle is found in steps of 0.5°, then 0.1°, then 0.02°. On test pages turned by known angles it comes within 0.1°. A page with too little on it, or without clear lines of text (a photo, a drawing), is not turned unless you set its tilt yourself.
Pages with real text are left as they are: a scanner cannot tilt text typed into a PDF. Pages without any picture are left too.
How the page is straightened
- A scanned page is drawn again at the scan's own resolution (or at 300 DPI when the page is more than one picture), turned back by its tilt with a smooth (bicubic) interpolation that keeps letters sharp, and cut back to the page's own size.
- The corners the turn leaves are filled with the paper's own colour, measured on the page, not with white or black, so they do not show.
- The page is saved as a picture again: black and white scans stay black and white, grey ones grey, colour ones colour, at about the scan's own quality. Check that every page reads clearly.
- The other pages are copied as they are. Links on a straightened page, and hidden text added by OCR, are not kept: run OCR PDF again afterwards if you need the text.
Questions
Can it fix a page photographed at an angle with my phone?
It fixes a page that is turned, not one that is slanted in perspective (wider at one end). For phone photos of pages, JPG to PDF lets you drag the four corners of the paper and flattens it.
A page is sideways or upside down, not just tilted.
Use Rotate PDF for quarter turns: it turns the page without redrawing it.
Does it make the PDF bigger?
Only a little, if at all: a straightened page is saved at about the quality its scan had. To get under a form's limit, use Compress PDF afterwards.
Is my PDF uploaded or stored?
No. It is measured and straightened in your browser; nothing is sent to ap7am or anywhere else.
Made with pdf-lib (MIT licence) and Mozilla's pdf.js (Apache 2.0 licence), both running in your browser.
Often used next తర్వాత ఎక్కువగా వాడేవి
More tools మరిన్ని టూల్స్
Straightened on your device: your PDF is never uploaded. Straightened scans are saved again as pictures: check that every page reads clearly.
