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:

Ubuntu	Debian	Fedora	RedHat	CentOS	OSX	Windows

Ubuntu or debian installation

On Linux Debian or Ubuntu, you may install the package with:

sudo apt-get install libpng12-dev

Fedora, RedHat or CentOS installation

On Fedora, RedHat or CentOS you may install the package with yum:

su -c "yum install libpng-devel"

Mac OSX installation

On OSX you may install the package with homebrew:

brew install libpng

Windows installation

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.

Tips and tricks

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.