Active Roles provides a policy (Built-in Policy - Picture Management Rules) to enforce the picture size limits, including maximal and minimal dimensions and the option to resize the picture automatically:
When you add a picture to the user, group or contact, Active Roles checks the dimensions of the picture, and does not apply the picture in case of policy violation. If automatic picture resizing is enabled, Active Roles reduces the dimensions of the picture as needed, by re-sampling down the original picture.
By default, the built-on Policy Object is applied to the Active Directory node in the Active Roles namespace, so the policy options affect all users, groups and contacts in the managed domains. If you need different policy options for different domains or containers, create a copy of the built-in Policy Object, and then configure and apply the copy as appropriate.