WordPress Automatically use Resized Images instead of originals

Replace your uploaded image with the large image generated by WordPress. This will save space on your server, and save bandwidth if you link your thumbnail to the original image. I love things that speed up your website.

 
function replace_uploaded_image($image_data) { 
// if there is no large image : return
 
 
if (!isset($image_data['sizes']['large'])) return $image_data; 
// paths to the uploaded image and the large image 
$upload_dir = wp_upload_dir(); 
$uploaded_image_location = $upload_dir['basedir'] . '/' .$image_data['file']; 
$large_image_location = $upload_dir['path'] . '/'.$image_data['sizes']['large']['file']; 
// delete the uploaded image 
unlink($uploaded_image_location); 
// rename the large image 
rename($large_image_location,$uploaded_image_location); 
// update image metadata and return them 
$image_data['width'] = $image_data['sizes']['large']['width']; 
$image_data['height'] = $image_data['sizes']['large']['height']; 
unset($image_data['sizes']['large']); 
 
return $image_data; 
} 
add_filter('wp_generate_attachment_metadata','replace_uploaded_image');