Deskew straightens scanned text documents: it finds the skew angle of the text lines
and rotates the image so they are horizontal. This page runs the Deskew command line tool
compiled to WebAssembly, so your images are processed on your computer and never uploaded.
Supported file formats
- Input
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- Output
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How to use it
- Open an image or drop it anywhere on the view. The skew angle is detected right away.
- Check the result: Original shows the detection area (red, dashed) and the found
content (green), Deskewed preview shows the rotated page and Work image the
thresholded image Deskew actually looked at.
- Adjust options if needed and click Deskew & download to get the output file.
Tips
- Zoom with the mouse wheel or a pinch, drag to pan, double click toggles between fit and 100 %.
- Outcome other than detected means the angle is not reliable and the image is not
rotated. Force rotation rotates it anyway.
- Pages with dark scanner borders or photos often do better with
Content area: Find automatically or with margins.
- If the angle hits the limit (At max angle limit), raise Max angle.
- Faint or very dark scans may need an explicit Threshold; the work image shows what
was considered to be text.
- Extra params takes any other command line option, e.g.
-f b1 for 1-bit
output or -p 300 to override DPI. See the full list below.
- Very large images may not fit: WebAssembly gives the page at most 4 GB of memory, and
the input, its grayscale copy and the rotated output all have to fit in it. For huge scans use the
Deskew command line tool or desktop GUI,
which are limited only by the memory of your computer.
All command line options
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