Libpng
Encyclopedia
libpng is the official Portable Network Graphics (PNG) reference
library
(originally called pnglib). It is a platform-independent library that contains C
functions for handling PNG images. It supports almost all of PNG's features, is extensible, and has been widely used and tested for over 15 years.
libpng is dependent on zlib
for data compression and decompression routines.
libpng is released under the libpng license
, a permissive free software licence
, and is free software
. It is frequently used in both free
and proprietary
software, either directly or through the use of a higher level image library.
Reference implementation
In the software development process, a reference implementation is the standard from which all other implementations, with their attendant customizations, are measured, and to which all improvements are added...
library
Library (computer science)
In computer science, a library is a collection of resources used to develop software. These may include pre-written code and subroutines, classes, values or type specifications....
(originally called pnglib). It is a platform-independent library that contains C
C (programming language)
C is a general-purpose computer programming language developed between 1969 and 1973 by Dennis Ritchie at the Bell Telephone Laboratories for use with the Unix operating system....
functions for handling PNG images. It supports almost all of PNG's features, is extensible, and has been widely used and tested for over 15 years.
libpng is dependent on zlib
Zlib
zlib is a software library used for data compression. zlib was written by Jean-Loup Gailly and Mark Adler and is an abstraction of the DEFLATE compression algorithm used in their gzip file compression program. Zlib is also a crucial component of many software platforms including Linux, Mac OS X,...
for data compression and decompression routines.
libpng is released under the libpng license
Libpng License
The libpng license is a permissive free software license, which defines the terms under which the libpng software library can be distributed.-Origin and history:...
, a permissive free software licence
Permissive free software licence
A permissive free software licence is a class of free software licence with minimal requirements about how the software can be redistributed. This is in contrast to copyleft licences, which have reciprocity / share-alike requirements. Both sets of free software licences offer the same freedoms in...
, and is free software
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
. It is frequently used in both free
Free software
Free software, software libre or libre software is software that can be used, studied, and modified without restriction, and which can be copied and redistributed in modified or unmodified form either without restriction, or with restrictions that only ensure that further recipients can also do...
and proprietary
Proprietary software
Proprietary software is computer software licensed under exclusive legal right of the copyright holder. The licensee is given the right to use the software under certain conditions, while restricted from other uses, such as modification, further distribution, or reverse engineering.Complementary...
software, either directly or through the use of a higher level image library.
External links
- libpng development home page
- libpng manual
- A howto on writing PNG images using libpng