Source Code and Information

    The road to wisdom? -- Well, it's plain
    and simple to express:
        Err
        and err
        and err again
        but less
        and less
        and less.

            --Piet Hein (Grooks)

Contents

This site contains well-tested C code for some basic image processing operations, along with a description of the functions and some design methods. A full set of affine transformations (translation, shear, rotation, scaling) on images of all depths is included, with the exception that some of the scaling methods do not work at all depths. There are also implementations of binary morphology, grayscale morphology, convolution and rank order filters, and applications such as jbig2 image processing and color quantization.

You will also find basic utilities for the safe and efficient handling of arrays (of strings, numbers, number pairs and image-related geometrical objects), generic and byte queues, stacks, lists, heaps, sets, ordered maps and hashmaps, as well as endian-independent indexing into 32-bit arrays.

There is a very high-level summary of the functions in the library. You can use this to quickly get an idea of where you may find a needed function.

Documentation external to the source code is provided for the following operations and applications:

1. Rasterops
   
   
2. Binary morphology
   
   
3. Grayscale morphology
   
   
4. Convolution
   
   
5. Scaling
   
   
6. Rotation
   
   
7. Affine transformations
   
   
8. Seed filling and connected components
   
   
9. Applications:
   • Jbig2 image processing
   • Color quantization
   • Color segmentation
   • Measuring image skew
   • Border representation of connected components
   • Dewarping text pages
   • Adaptive character recognition
   
   
10. Grayscale and color image enhancement
    
    
11. Grayscale mapping and binarization
    
    
12. Connectivity-preserving thinning
    
    
13. Playing around

Download

Click here to download a source release. [ update: Jan 3, 2024 ]

Be sure to download the README as well.

If you are building the library and applications on Windows, the sw package is available on the github repository. There you can obtain the latest release and build the library using cmake.

You may also find these pages useful:

• brief notes on the version history
• high-level summary of the contents of the leptonica library, organized by related functions
• notes on utilities that help with multi-platform (Unix and Windows) application programming.
• information on the library contents and usage
• an explanation of the byte-ordering conventions used in the leptonica library

Related Publications

Here are some references to selected papers on image processing and image analysis that you might find interesting.

Luc Vincent and I wrote a chapter on Document image analysis, in Mathematical morphology: theory and applications, published by ISTE-Wiley in June 2010. The book is is a compendium on topics in morphology, edited by Laurent Najman and Hugues Talbot. Here is a page that provides information, including the location of source code for running the applications and generating the figures for this chapter.

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