Preprocessing Fields from a Module in Drupal 7

If you're looking to preprocess a field in Drupal 7, you can use hook_preprocess_HOOK. The first "hook" is the name of your module. The second "HOOK" is the theme hook you want to preprocess (e.g. theme_node, theme_block, theme_link, theme_field). You can fine an exhustive list of the Drupal theme hooks by searching the Drupal API.

Here is a simple example of how to use it with fields.

function mymodule_preprocess_field(&$variables) {
   if ($variables['element']['#field_name'] == 'field_myfield') {
   // do something

Voila! Now you have access to preprocess fields... even ones you didn't create.

A quick tip: In order to preprocess a single field, use a conditional statement to check the "#field_name".