How do I crop only height? I want to crop an image that is anchored at the center, but only crop the height.  How can this be done in Drupal 7?

EDIT: The process needs to be automated.  Basically I desire the functionality of the existing crop process for an image style, but without the requirement for having to enter a value for both width and height.

EDIT #2:  The width needs to be variable :)
You'll have to use custom GD methods I think. 

Have a look at this module : https://drupal.org/project/imagecache_actions

With the embed "Custom Actions" module you'll be able to use any gd method you want.

Add a custom filter to an image filter, and find the gd function to use.

In example, to get a B&amp;W picture, the php code to use is : 

return imagefilter($image-&gt;resource, IMG_FILTER_GRAYSCALE);