gif2png software package provides GIF -> PNG conversions, you can install in your Debian 7 (Wheezy) by running the commands given below on the terminal,
$ sudo apt-get update $ sudo apt-get install gif2png
gif2png is installed in your system.
Make ensure the gif2png package were installed using the commands given below,
$ sudo dpkg-query -l | grep gif2png *
You will get with gif2png package name, version, architecture and description in a table
| Distro | Debian 7 wheezy |
| Section | Graphics |
| Package | gif2png |
| Version | 2.5.8-1 |
| Description | GIF -> PNG conversions |
| Sub Section | Graphics |