下面这个脚本能使WordPress生成一个大幅图片，并用该图片代替用户所上传的图片（如果所上传图片尺寸大于用户的后台设置），以节省服务器空间，如果你链接到的是原始图片的缩略图，还可以节省带宽，效果和lightbox插件一样。
只要将以下代码添加到functions.php文件并保存即可。
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');
注意：不同主题对该代码的支持程度会有所不同
原文：How to automatically use resized images instead of originals
分类：新闻资讯