INSTALLING GRAPHICS UTILITIES
There's a very useful image processing utility called convert - it will convert images from one format to another, resize them and all sorts of other transformations.
To install ImageMagick, follow the steps below:
First, ensure that the package cache is up to date:
sudo apt-get update
Now install ImageMagick:
sudo apt-get install imagemagick
For more information on convert, go to ImageMagick.