Создание Image Style программно

$style = image_style_save(array('name' => 'Catalog Medium (255x255)'));
  $effect = array(
    'name' => 'image_scale',
    'data' => array(
      'width' => 255,
      'height' => 255,
      'upscale' => TRUE,
    ),
    'isid' => $style['isid'],
  );
  image_effect_save($effect);

Источник: http://www.drupalfoo.com/drupal-7-creating-image-style-programatically-module