i need a fast and reliable way to modify a lot of images.
There is a lot of white around my pictures i want to get rid about.
The problem is, it is a number of similar pictures, but they have different sizes.
An example is here: [a link](http://www2.chemie.uni-erlangen.de/projects/vsc/chemie-mediziner-neu/atombau/orbitale.html) My pictures have only the red and blue part and a huge white space around them.
I want pictures with the same format and less white space.

First i would need the maximum dimension of the non-white part of all pictures and then crop all pictures to the format of the biggest dimension. But the center of the image has to stay the center.

Is this somehow possible with convert or any other command line tool?