Find missing or not readable product image files in Magento1.

fmpif.php

<?php
/**
 * Find missing or not readable product image files in Magento1.
 * Run this file via command line ( php fmpif.php ) or open it in your web browser.
 *
 * @copyright   Copyright (c) 2016 Tobias Forkel (http://www.tobiasforkel.de)
 * @license     http://opensource.org/licenses/osl-3.0.php Open Software License (OSL 3.0)
 */

require_once 'app/Mage.php';
Mage::app();

// Collection of all products
$products = Mage::getModel('catalog/product')->getCollection();

// Get absolute path to media folder
$media = Mage::getBaseDir('media');

// Count missing files
$i = 0;

foreach ($products as $_product)
{
    $product = Mage::getModel('catalog/product')->load($_product->getId());

    foreach ($product->getMediaGalleryImages() as $image)
    {
        $file = $media . '/catalog/product' . $image['file'];

        if (!is_readable($file))
        {
            $i++;
            echo sprintf('The image file (%s) from product SKU number (%s) doesn\'t exists or is not readable.', $file, $_product->getSku());
        }
    }
}

if ($i == 0)
{
    echo 'All good!';
}

?>