png 3rd party
Since ViSP 2.8.0 it is not useful to install this 3rd party if OpenCV is used in ViSP.
The libpng library is a C library which enables to read and write PNG files. It can be downloaded from http://www.libpng.org/pub/png/libpng.html. libpng is licensed under the terms of the ZLib license.
The libpng library depends on ZLib library that needs also to be installed.
Hereafter we provide installation instructions for the following OS:
On Linux Debian or Ubuntu, you may install the package with:
sudo apt-get install libpng12-dev
On Fedora, RedHat or CentOS you may install the package with yum:
su -c "yum install libpng-devel"
On OSX you may install the package with homebrew:
brew install libpng
If you use Windows, we recommand to install zlib and libpng from source code by using CMake. All the required informations to do it are provided on http://www.libpng.org/pub/png/libpng.html. Build both libraries in debug and release and don’t forget to install each one by building the INSTALL project.
In order that zlib1.dll and libpng.dll are found during execution, you should add C:\zlib_and_libpng_install_path\bin in the PATH environment variable.
If libpng is not detected during ViSP configuration step, you can create an environment variable called “LIBPNG_DIR” and set it to the path corresponding to the folder containing the library.