Show an image field using field_view_field and colorbox

blocks.inc

        $build = field_view_field('user', $context['entity'], 'field_picture', array(
          'label' => 'hidden',
          'type' => 'colorbox',
          'settings' => array(
            'colorbox_node_style' => 'user_large',
            'colorbox_image_style' => 'colorbox',
          ),
        ));