<?php
    $image_orig = "sample_image.png";
    $resize = 0.4; // Resize factor
    header("Content-Type: image/jpeg");
    list($width, $height) = getimagesize($image_orig);
    
    // new size
    $newwidth = $width * $resize;
    $newheight = $height * $resize;
    
    // create
    $image_new = imagecreatetruecolor($newwidth, $newheight);
    $image_src = imagecreatefromjpeg($image_orig);
    imagecopyresized($image_new, $image_src, 0, 0, 0, 0, $newwidth, $newheight, $width, $height);
?>