Internal Program Version:  Leptonica 1.68  (The HEADER-Files)

Well-tested C library 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), byte queues, generic stacks, generic
lists, and endian-independent indexing into 32-bit arrays.

http://www.leptonica.org/