how to create new image size with new image style with php code in drupal 7? I want to create a new image style in Drupal 7, with a name like front_video_thumbnail. I want to use this size image on front page. I wrote code in template.php preprocess_page(), like the following one.

$img = theme('image_style', array('style_name' =&gt; 'front_video_thumnail', 'path' =&gt; $value['uri']));
$content =l($img, $node_url, array('html' =&gt; TRUE));


No image is showing, because no image has been created in the new style folder. 

How can I make this new image style created in the style folder?
You have to go to Configuration => Image Styles. Create the Image Style with the name front_video_thumnail and once it's configuration is saved your code should work.