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An open source C library for efficient image processing and image analysis operations

Leptonica Library
The library supports many operations that are useful on

    * Document images
    * Natural images 

Fundamental image processing and image analysis operations

    * Rasterop (aka bitblt)
    * Affine transforms (scaling, translation, rotation, shear) on images of arbitrary pixel depth
    * Binary and grayscale morphology, rank order filters, and convolution
    * Seedfill and connected components
    * Image transformations with changes in pixel depth, both at the same scale and with scale change
    * Pixelwise masking, blending, enhancement, arithmetic ops, etc. 

Ancillary utilities

    * I/O for standard image formats (jpg, png, tiff, bmp, pnm, gif, ps)
    * Utilities to handle arrays of image-related data types (e.g., pixa, boxa, pta)
    * Utilities for stacks, generic arrays, queues, heaps, lists; number and string arrays; etc. 

Examples of some applications enabled and implemented

    * Octcube-based color quantization (w/ and w/out dithering)
    * Modified median cut color quantization (w/ and w/out 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 wrapping (levels 1, 2) of images for device-independent output
    * Connectivity-preserving thinning and thickening of 1 bit/pixel images
    * Search for least-cost paths on binary and grayscale images
    * Barcode reader for 1D barcodes (very early version as of 1.55) 

Implementation characteristics

    * Efficient: image data is packed binary (into 32-bit words); operations on 32-bit data whenever possible
    * Simple: small number of data structures; simplest implementations provided that are efficient
    * Thread-safe: no non-const global vars
    * Consistent: data allocated on the heap with simple ownership rules; function names usually begin with primary data structure (e.g., pix)
    * Robust: all ptr args checked; extensive use of accessors; exit not permitted
    * Tested: thorough regression tests provided for most basic functions; valgrind tested
    * Ansi C: automatically generated prototype header file
    * Portable: endian-independent; builds in linux, osx, mingw, cygwin, windows
    * Documentation: large number of in-line comments; web pages for further background
    * Examples: many programs provided to test and show usage of approx. 1500 functions in the library 

Open Source Projects that use Leptonica

    * php (scripting language for dynamic web pages)
    * tesseract (optical character recognition)
    * jbig2enc (encodes multipage binary image documents with jbig2 compression) 

Source Files

Filename Size Changed Actions
leptonica.spec 4.58 KB over 9 years ago Download File
leptonlib-1.60.tar.gz 3.92 MB over 9 years ago Download File
wizard.xml 3.28 KB over 9 years ago Download File

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