Replace IMG src link tag with IMG embed content encoded in base64

convert.php

<?php
/**
 * @author Nicolas Potier <[email protected]>
 * 
 * Convert img src="" present in HTML page to <img src="data:image..." 
 * This Script is inspired by https://joekuan.wordpress.com/2015/02/01/converting-html-document-with-img-src-link-to-img-embedded-data-in-php/
 * 
 * usage : php convert.php source.html destination.html 
 *
 */
 
$srcfilepath = $argv[1];
$dstfilepath = $argv[2];

$srcDir = dirname($srcfilepath);
$srcName = basename($srcfilepath);

// Read the whole template file into memory
if (($template_content = file_get_contents($srcfilepath)) === false) {
    fprintf($stderr, "Unable to read html file: {$srcfilepath}\n");
    return false;
}

// Match the IMG tag one at a time
$offset = 0;

while (preg_match('/<img src="([^"]*)"/i', $template_content, $match, PREG_OFFSET_CAPTURE, $offset) >= 1) {
    $matchTag = $match[0][0];
    $matchOffset = $match[0][1];
    $imgFile = $srcDir.'/'.$match[1][0];
    $ext = pathinfo($imgFile, PATHINFO_EXTENSION);

    if (!file_exists($imgFile)) {
        echo "Unable to find image file {$imgFile}\n";
        return;
    }

    $img_tag = "<img src='data:image/".$ext.";base64," . base64_encode(file_get_contents($imgFile)) . "'";
    // Replace the IMG src link tag with IMG embed content
    $template_content = substr_replace($template_content, $img_tag, $matchOffset, strlen($matchTag));

    // offset for next loop
   $offset = $matchOffset + strlen($img_tag);
}

file_put_contents($dstfilepath, $template_content);