Updated: June 11, 2021
Leptonica is a pedagogically-oriented open source site
containing software that is broadly useful for image processing
and image analysis applications.
Featured operations are
- Rasterop (a.k.a. bitblt)
- Affine transformations (scaling, translation, rotation, shear)
on images of arbitrary pixel depth
- Binary and grayscale morphology, rank order, and convolution
- Seedfill and connected components
- Image transformations combining changes in scale and pixel depth
- Pixelwise masking, blending, enhancement, arithmetic ops, etc.
Ancillary operations include
- I/O for standard image formats
- Utilities to handle arrays of image-related data types
- Utilities for generic stacks, queues, heaps and lists;
and for byte queues and arrays of numbers and strings
Example applications include
- Octcube-based color quantization, with and without dithering
- Modified median-cut color quantization, with and without dithering
- Skew determination of text images
- Segmentation of page images with mixed text and images
- jbig2 unsupervised classifier
- Border representations of 1 bit/pixel images and raster
conversion for SVG
- PostScript generation (levels 1, 2, 3) of images for
- PDF generation (levels 1, 2) of images for device-independent output
- Dewarping images of text taken with a camera
- Book-adaptive text recognition
- Rendering text on an image
- Connectivity-preserving thinning and thickening of 1 bit/pixel images
- Line removal from a grayscale sketch
- Search for least-cost paths on binary and grayscale images
Reference documentation for users
- The Leptonica image processing and analysis source code comes
with a very weakly restricted
- The README
gives an overview of installation and usage, with a brief
description of the library contents.
- A page of brief notes on version
- A high-level view of the source
files in the library.
- For a deeper look into specific components of the library,
see the web pages linked from the
image processing page.
- Tom Powers has built the
Unofficial Leptonica Documentation.
It only covers the versions up to 1.68 (2011), but is more
easily navigated. You can use it, but be aware that some
information is no longer valid.
- Uncompleted sets of somewhat detailed
usage notes and a
lightweight overview have been attempted but are unlikely
to be completed anytime in the current millenium.
- The final arbiter is, of course, the source itself.
- Click here to download
[ update: June 11, 2021 ]
- See here for further
information about the source code.
Contact: Dan Bloomberg (bloomberg "at" ieee "dot" org) for
questions and suggestions
Leptonica is licensed by Dan Bloomberg
under a Creative Commons
Attribution 3.0 United States License.
© Copyright 2001-2020, Leptonica