<?php
$postText = '..includes html + image tags';
 
// find first image and redo it
preg_match_all('/<img[^>]+>/i', $postText, $images);
$postThumbnail = isset($images[0][0]) ? $images[0][0] : '';
$postThumbnail = preg_replace('/(width|height|style)="*"/', '', $postThumbnail);
$postThumbnail = preg_replace('/<img/', '<img class="blog-post-thumbnail"', $postThumbnail);
 
echo $postThumbnail;
echo $postText;
?>

http://www.apphp.com/index.php?snippet=php-change-image-properties-on-fly

Sometimes you may need to change image properties 'on-the-fly'. The best example is when you want to display blog post short description, retrieve the first image and try to turn it into the thumbnail: change some properties and add a special class name.

Change Image Properties 'On-The-Fly'

php, image

PHP