You might want to run 'apt --fix-broken install' to correct these.
The following packages have unmet dependencies:
libpng3 : Depends: libpng12-0 (>= 1.2.5.0-2) but it is not going to be installed
E: Unmet dependencies. Try 'apt --fix-broken install' with no packages (or specify a solution).
Ubuntu 20.04, 19.10 或者 19.04中，可以通过PPA安装libpng，安装PPA及libpng12-0的命令如下。在终端命令输入：
sudo add-apt-repository ppa:linuxuprising/libpng12
sudo apt update
sudo apt install libpng12-0
