PHP Script: Make your own Thumbnail Generator via API

: Category: Zoho; 29 May 2025; Hits: 1463

What?
Looking for an online tool that will take an image and make a thumbnail copy? This article is for me if I ever want to recreate an online tool capable of receiving an image URL and which both generates and outputs a thumbnail image and makes it downloadable via URL.

Why?
Performance. I have a client with about 10k images of products that they want to appear in a dropdown menu of a JavaScript widget. When the user first loads up the webpage containing the widget, 10k images are downloaded. I have put in a lazy loading process where it will load the first few images and as the user scrolls down the dropdown, more are loaded. This still gets buggy on certain mobile devices as some images are over 1Mb.

So I needed a tool that every time a new product is added, a thumbnail gets generated and stored in the same application. Trawling through the first few pages of Google, all the online tools that did the same had a pricing page. I can understand why you would need to limit users so I don't blame them. But if you can, why not make your own?

How?
So you will need a webserver of your own running PHP 8. The following PHP script was only tested using PHP version 8.x so I can't say whether it will work for previous versions.

I cannot take credit for this script, as I asked OpenAI's ChatGPT to write it initially, and to build upon it as I kept moving the goal posts, figuratively speaking, and changing the requirements. I am impressed however that every version it iterated, worked exactly as I asked with only 1 error where it mixed a method with a comment but thereafter, a working script every time.

The PHP Script: I'm calling it thumbnailer.php

Deploy the Script
Place thumbnailer.php into a web-accessible directory on your server (for example, public_html/api/thumbnailer.php). It will be called as a JSON API over GET and does not render a webpage.
Create Storage Folders
In the same directory, create two writable subfolders:
- _origs/ — stores the original downloaded images
- _thmbs/ — stores the 75×75 thumbnail images
Ensure both folders are writable by your web-server user (e.g. www-data).
Client-Specific Subfolders
The script automatically creates per-client subdirectories inside both _origs and _thmbs when you supply a client key in the request. You do not need to pre-create those.
Secure Access via GET
All calls must include:
- name — the output file name without the extension
- url — the source image URL
- auth — your daily MD5 API key
- client — your lowercase alphanumeric client identifier
Requests missing or failing any parameter will be rejected with a JSON error.
Example Request
copyrawstyler
```
https://your-domain.com/api/thumbnailer.php?
 			url=https://picsum.photos/400
 			&name=test_photo
 			&client=joellipman
 			&auth=YOUR_DAILY_KEY
```
1. https://your-domain.com/api/thumbnailer.php?
2. url=https://picsum.photos/400
3. &name=test_photo
4. &client=joellipman
5. &auth=YOUR_DAILY_KEY
On success, you’ll receive:
copyrawstyler
```
{
  "original": "https://your-domain.com/api/_origs/joellipman/test_photo.jpg",
  "thumbnail": "https://your-domain.com/api/_thmbs/joellipman/test_photo_75x75.jpg"
}
```
1. {
2. "original": "https://your-domain.com/api/_origs/joellipman/test_photo.jpg",
3. "thumbnail": "https://your-domain.com/api/_thmbs/joellipman/test_photo_75x75.jpg"
4. }
Permissions & Logging
• Ensure PHP can write to _origs and _thmbs.
• Optionally monitor or rotate logs for download and processing errors.

copy raw

<?php
/**
 * PHP Thumbnail Generator with Dynamic Auth, Extended Format Support,
 * URL Parameter, Custom Output Name, JSON Response, Original Image Storage,
 * and Client-based Subfolders
 *
 * Accepts via GET:
 * - 'url'    (image URL, required)
 * - 'name'   (custom base filename, optional)
 * - 'auth'   (API key, required; must match md5(internal_auth_key_1 . internal_auth_key_2 . the_client_name . date('d-M-Y')))
 * - 'client' (client identifier, required; lowercase, alphanumeric, hyphens/underscores)
 *
 * If 'auth' is invalid, returns HTTP 403 with JSON {"error":"invalid key"}.
 * If 'client' is invalid or missing, returns HTTP 400 with JSON {"error":"invalid client"}.
 * Otherwise, downloads the image, stores the original in '_origs/{client}',
 * creates a 75x75 thumbnail in '_thmbs/{client}', and returns JSON with both URLs.
 * Supports JPEG, PNG, GIF, WebP, BMP (GD), HEIC/others (Imagick).
 *
 * Changelog:
  * v1.0.0 2025-05-28: - Initial Release
 *  - Basic script to download an image from a hard-coded URL.
 *  - Resizes to 75x75 pixels using GD.
 *  - Saves thumbnail in a Thumbnails directory.
 *
 * v1.1.0 2025-05-28: - Added Format Support
 *  - Added support for PNG and GIF formats (with transparency preservation).
 *  - Detects image type via getimagesize() and calls the appropriate GD loader.
 *
 * v1.2.0 2025-05-28: - WebP Support
 *  - Added detection and handling for WebP images.
 *  - Uses imagecreatefromwebp()/imagewebp() when available.
 *  - Error message if WebP support is missing in PHP.
 *
 * v1.3.0 2025-05-28: - BMP and HEIC Support
 *  - Added BMP support via imagecreatefrombmp()/imagebmp().
 *  - Added HEIC (and other formats) support via Imagick fallback.
 *  - HEIC handled by Imagick::cropThumbnailImage() when GD cannot process.
 *
 * v1.4.0 2025-05-28: - Basic Authentication
 *  - Added private key basic authentication including date. 
 *  - Returns a JSON payload with both original and thumbnail URLs.
 *
 * v1.5.0 2025-05-28: - Custom Folders and Client Subfolders
 *  - Changed destination folder from Thumbnails to _thmbs and originals to _origs.
 *  - Automatically creates per-client subdirectories when &client= is passed.
 *  - Included client name in authentication
 *
 * v1.6.0 2025-05-29: - JSON Response & Original URL
 *  - Ensures originals are saved with their original file extensions.
 *
 * v1.7.0 2025-05-29: - Filename Suffix Change
 *  - Changed thumbnail suffix from _thumb to _75x75 to reflect dimensions.
 *
 * v1.8.0 2025-05-29: - Aspect Ratio & Background Fill
 *  - Retains source aspect ratio when resizing.
 *  - Outputs a square 75x75 thumbnail by centering on a white canvas.
 *  - Implements both GD and Imagick branches for background fill.
 *
 * v1.9.0 2025-05-29: - Force JPEG Output for Thumbnails
 *  - Force thumbnail to always be JPG (compression at 90)
 *
 * v1.10.0 2025-06-18: - AVIF compatibility
 *  - Handle AVIF image format
 *  - Upload and convert original to JPG format
 *  */

header('Content-Type: application/json');

// Validate client parameter
$clientRaw = filter_input(INPUT_GET, 'client', FILTER_SANITIZE_STRING);
$client    = preg_match('/^[a-z0-9_-]+$/', $clientRaw) ? $clientRaw : '';
if (!$client) {
    header('HTTP/1.1 400 Bad Request');
    echo json_encode(['error' => 'invalid client']);
    exit;
}

// Validate API auth parameter (change the $auth1 and $auth2 values and match these to the requesting script)
$auth     = filter_input(INPUT_GET, 'auth', FILTER_SANITIZE_STRING);
$auth1    = "just_some_random_key_about_64_characters_long_of_alphanumeric_and_symbols";
$auth2    = "another_random_key_about_64_characters_long_of_alphanumeric_and_symbols";
$today    = date('d-M-Y');
$expected = md5($auth1 . $auth2 . $client . $today);
if ($auth !== $expected) {
    header('HTTP/1.1 403 Forbidden');
    echo json_encode(['error' => 'invalid key']);
    exit;
}

// *********** NO NEED TO CHANGE ANYTHING BELOW THIS COMMENT LINE ***********

// Fetch and validate URL
$url    = filter_input(INPUT_GET, 'url', FILTER_VALIDATE_URL);
if (!$url) {
    header('HTTP/1.1 400 Bad Request');
    echo json_encode(['error' => "Provide a valid 'url' parameter."]);
    exit;
}

// Determine base filename
$customName = filter_input(INPUT_GET, 'name', FILTER_SANITIZE_STRING);
if ($customName) {
    $baseName = preg_replace('/[^A-Za-z0-9_-]/', '', $customName);
    if ($baseName === '') {
        header('HTTP/1.1 400 Bad Request');
        echo json_encode(['error' => "'name' invalid—use letters, numbers, hyphens, underscores."]);
        exit;
    }
} else {
    $baseName = pathinfo(parse_url($url, PHP_URL_PATH), PATHINFO_FILENAME);
}

// Settings: client-specific directories
$originalFolder  = __DIR__ . '/_origs/' . $client;
$thumbnailFolder = __DIR__ . '/_thmbs/' . $client;
$thumbWidth      = 75;
$thumbHeight     = 75;

// Ensure directories exist (creates parent paths automatically)
foreach ([$originalFolder, $thumbnailFolder] as $dir) {
    if (!is_dir($dir) && !mkdir($dir, 0755, true)) {
        header('HTTP/1.1 500 Internal Server Error');
        exit(json_encode(['error' => "Failed to create directory: $dir"]));
    }
}

// Base URL paths
$protocol     = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS']!=='off') ? 'https' : 'http';
$host         = $_SERVER['HTTP_HOST'];
$scriptDir    = rtrim(dirname($_SERVER['PHP_SELF']), '/');
$origBaseURL  = "$protocol://$host$scriptDir/_origs/$client";
$thumbBaseURL = "$protocol://$host$scriptDir/_thmbs/$client";

// Download source to temp file
$tempFile = tempnam(sys_get_temp_dir(), 'img_');
$imgData  = @file_get_contents($url);
if (!$imgData || file_put_contents($tempFile, $imgData) === false) {
    header('HTTP/1.1 502 Bad Gateway');
    exit(json_encode(['error' => 'Failed to download image.']));
}

// Validate image
$info = @getimagesize($tempFile);
if (!$info) {
    unlink($tempFile);
    header('HTTP/1.1 415 Unsupported Media Type');
    exit(json_encode(['error' => 'Downloaded file is not a valid image.']));
}
list($origW, $origH, $type) = $info;

// Ensure AVIF constant
if (!defined('IMAGETYPE_AVIF')) define('IMAGETYPE_AVIF', 19);

// Convert and save original as JPEG
if (class_exists('Imagick')) {
    try {
        $imOrig = new Imagick($tempFile);
        $imOrig->setImageFormat('jpeg');
        $imOrig->writeImage($origPath);
        $imOrig->destroy();
    } catch (Exception $e) {
        // fallback to GD
    }
}

// Determine base filename
$path    = parse_url($url, PHP_URL_PATH);
$urlBase = pathinfo($path, PATHINFO_FILENAME);
$base    = $customName
    ? preg_replace('/[^a-zA-Z0-9_-]/', '', $customName)
    : $urlBase;
$mimeExtMap = [
    IMAGETYPE_JPEG=>'jpg',IMAGETYPE_PNG=>'png',IMAGETYPE_GIF=>'gif',
    IMAGETYPE_WEBP=>'webp',IMAGETYPE_BMP=>'bmp', IMAGETYPE_AVIF => 'avif'
];
$origExt      = $mimeExtMap[$type] ?? 'img';
$origFilename = "$base.$origExt";

// Save original in client folder
copy($tempFile, "$originalFolder/$origFilename");

// Prepare thumbnail filename (JPEG)
$thumbFilename = $base . "_{$thumbWidth}x{$thumbHeight}.jpg";
$thumbPath     = "$thumbnailFolder/$thumbFilename";

// JSON error helper
function errorJson($msg, $code=500) {
    http_response_code($code);
    exit(json_encode(['error'=>$msg]));
}

// Generate thumbnail (Imagick if available)
if (class_exists('Imagick')) {
    try {
        $im     = new Imagick($tempFile);
        $im->thumbnailImage($thumbWidth, $thumbHeight, true);
        $w      = $im->getImageWidth();
        $h      = $im->getImageHeight();
        $canvas = new Imagick();
        $canvas->newImage($thumbWidth, $thumbHeight, new ImagickPixel('white'));
        $canvas->compositeImage($im, Imagick::COMPOSITE_OVER, ($thumbWidth-$w)/2, ($thumbHeight-$h)/2);
        $canvas->setImageFormat('jpeg');
        $canvas->writeImage($thumbPath);
        $im->destroy(); $canvas->destroy(); unlink($tempFile);
        header('Content-Type:application/json');
        exit(json_encode(['original'=>"$origBaseURL/$origFilename", 'thumbnail'=>"$thumbBaseURL/$thumbFilename"]));
    } catch (Exception $e) {
        unlink($tempFile);
        errorJson('Imagick error: '.$e->getMessage());
    }
}

// Fallback to GD
switch ($type) {
    case IMAGETYPE_JPEG: $src=imagecreatefromjpeg($tempFile); break;
    case IMAGETYPE_PNG:  $src=imagecreatefrompng($tempFile);  break;
    case IMAGETYPE_GIF:  $src=imagecreatefromgif($tempFile);  break;
    case IMAGETYPE_WEBP:
        if (!function_exists('imagecreatefromwebp')) errorJson('WebP not supported');
        $src=imagecreatefromwebp($tempFile); break;
    case IMAGETYPE_BMP:
        if (!function_exists('imagecreatefrombmp')) errorJson('BMP not supported');
        $src=imagecreatefrombmp($tempFile); break;
    case IMAGETYPE_AVIF:
        if (!function_exists('imagecreatefromavif')) errorJson('AVIF not supported');
        $src=imagecreatefromavif($tempFile); break; 
    default:
        unlink($tempFile);
        errorJson('Unsupported image format', 415);
}
// Create white canvas and prepare thumbnail

    // Initialize a white background canvas of size {$thumbWidth}×{$thumbHeight}
    $thumb = imagecreatetruecolor($thumbWidth, $thumbHeight);
    $whiteColor = imagecolorallocate($thumb, 255, 255, 255);
    imagefilledrectangle(
        $thumb,      // destination image
        0, 0,        // top-left corner
        $thumbWidth, // width
        $thumbHeight,// height
        $whiteColor  // fill color
    );

    // Calculate aspect ratio to fit the original image into the square canvas
    $ratio    = min($thumbWidth / $origW, $thumbHeight / $origH);
    $newW     = (int) ($origW * $ratio);
    $newH     = (int) ($origH * $ratio);

    // Calculate centering offsets
    $offsetX  = (int) (($thumbWidth  - $newW) / 2);
    $offsetY  = (int) (($thumbHeight - $newH) / 2);

    // Copy and resize original onto the canvas
    imagecopyresampled(
        $thumb,     // destination
        $src,       // source
        $offsetX,   // dest x
        $offsetY,   // dest y
        0,          // src x
        0,          // src y
        $newW,      // dest width
        $newH,      // dest height
        $origW,     // src width
        $origH      // src height
    );

// Save JPEG thumbnail
imagejpeg($thumb,$thumbPath,90);

// Cleanup
imagedestroy($src); 
imagedestroy($thumb); 
unlink($tempFile);

// Return JSON
header('Content-Type:application/json');
echo json_encode([
    'original'=>"$origBaseURL/$origFilename", 
    'thumbnail'=>"$thumbBaseURL/$thumbFilename"
]);

?>

<?php
/**
* PHP Thumbnail Generator with Dynamic Auth, Extended Format Support,
* URL Parameter, Custom Output Name, JSON Response, Original Image Storage,
* and Client-based Subfolders
*
* Accepts via GET:
* - 'url' (image URL, required)
* - 'name' (custom base filename, optional)
* - 'auth' (API key, required; must match md5(internal_auth_key_1 . internal_auth_key_2 . the_client_name . date('d-M-Y')))
* - 'client' (client identifier, required; lowercase, alphanumeric, hyphens/underscores)
*
* If 'auth' is invalid, returns HTTP 403 with JSON {"error":"invalid key"}.
* If 'client' is invalid or missing, returns HTTP 400 with JSON {"error":"invalid client"}.
* Otherwise, downloads the image, stores the original in '_origs/{client}',
* creates a 75x75 thumbnail in '_thmbs/{client}', and returns JSON with both URLs.
* Supports JPEG, PNG, GIF, WebP, BMP (GD), HEIC/others (Imagick).
*
* Changelog:
* v1.0.0 2025-05-28: - Initial Release
* - Basic script to download an image from a hard-coded URL.
* - Resizes to 75x75 pixels using GD.
* - Saves thumbnail in a Thumbnails directory.
*
* v1.1.0 2025-05-28: - Added Format Support
* - Added support for PNG and GIF formats (with transparency preservation).
* - Detects image type via getimagesize() and calls the appropriate GD loader.
*
* v1.2.0 2025-05-28: - WebP Support
* - Added detection and handling for WebP images.
* - Uses imagecreatefromwebp()/imagewebp() when available.
* - Error message if WebP support is missing in PHP.
*
* v1.3.0 2025-05-28: - BMP and HEIC Support
* - Added BMP support via imagecreatefrombmp()/imagebmp().
* - Added HEIC (and other formats) support via Imagick fallback.
* - HEIC handled by Imagick::cropThumbnailImage() when GD cannot process.
*
* v1.4.0 2025-05-28: - Basic Authentication
* - Added private key basic authentication including date.
* - Returns a JSON payload with both original and thumbnail URLs.
*
* v1.5.0 2025-05-28: - Custom Folders and Client Subfolders
* - Changed destination folder from Thumbnails to _thmbs and originals to _origs.
* - Automatically creates per-client subdirectories when &client= is passed.
* - Included client name in authentication
*
* v1.6.0 2025-05-29: - JSON Response & Original URL
* - Ensures originals are saved with their original file extensions.
*
* v1.7.0 2025-05-29: - Filename Suffix Change
* - Changed thumbnail suffix from _thumb to _75x75 to reflect dimensions.
*
* v1.8.0 2025-05-29: - Aspect Ratio & Background Fill
* - Retains source aspect ratio when resizing.
* - Outputs a square 75x75 thumbnail by centering on a white canvas.
* - Implements both GD and Imagick branches for background fill.
*
* v1.9.0 2025-05-29: - Force JPEG Output for Thumbnails
* - Force thumbnail to always be JPG (compression at 90)
*
* v1.10.0 2025-06-18: - AVIF compatibility
* - Handle AVIF image format
* - Upload and convert original to JPG format
* */
header('Content-Type: application/json');
// Validate client parameter
$clientRaw = filter_input(INPUT_GET, 'client', FILTER_SANITIZE_STRING);
$client = preg_match('/^[a-z0-9_-]+$/', $clientRaw) ? $clientRaw : '';
if (!$client) {
header('HTTP/1.1 400 Bad Request');
echo json_encode(['error' => 'invalid client']);
exit;
}
// Validate API auth parameter (change the $auth1 and $auth2 values and match these to the requesting script)
$auth = filter_input(INPUT_GET, 'auth', FILTER_SANITIZE_STRING);
$auth1 = "just_some_random_key_about_64_characters_long_of_alphanumeric_and_symbols";
$auth2 = "another_random_key_about_64_characters_long_of_alphanumeric_and_symbols";
$today = date('d-M-Y');
$expected = md5($auth1 . $auth2 . $client . $today);
if ($auth !== $expected) {
header('HTTP/1.1 403 Forbidden');
echo json_encode(['error' => 'invalid key']);
exit;
}
// *********** NO NEED TO CHANGE ANYTHING BELOW THIS COMMENT LINE ***********
// Fetch and validate URL
$url = filter_input(INPUT_GET, 'url', FILTER_VALIDATE_URL);
if (!$url) {
header('HTTP/1.1 400 Bad Request');
echo json_encode(['error' => "Provide a valid 'url' parameter."]);
exit;
}
// Determine base filename
$customName = filter_input(INPUT_GET, 'name', FILTER_SANITIZE_STRING);
if ($customName) {
$baseName = preg_replace('/[^A-Za-z0-9_-]/', '', $customName);
if ($baseName === '') {
header('HTTP/1.1 400 Bad Request');
echo json_encode(['error' => "'name' invalid--use letters, numbers, hyphens, underscores."]);
exit;
}
} else {
$baseName = pathinfo(parse_url($url, PHP_URL_PATH), PATHINFO_FILENAME);
}
// Settings: client-specific directories
$originalFolder = __DIR__ . '/_origs/' . $client;
$thumbnailFolder = __DIR__ . '/_thmbs/' . $client;
$thumbWidth = 75;
$thumbHeight = 75;
// Ensure directories exist (creates parent paths automatically)
foreach ([$originalFolder, $thumbnailFolder] as $dir) {
if (!is_dir($dir) && !mkdir($dir, 0755, true)) {
header('HTTP/1.1 500 Internal Server Error');
exit(json_encode(['error' => "Failed to create directory: $dir"]));
}
}
// Base URL paths
$protocol = (!empty($_SERVER['HTTPS']) && $_SERVER['HTTPS']!=='off') ? 'https' : 'http';
$host = $_SERVER['HTTP_HOST'];
$scriptDir = rtrim(dirname($_SERVER['PHP_SELF']), '/');
$origBaseURL = "$protocol://$host$scriptDir/_origs/$client";
$thumbBaseURL = "$protocol://$host$scriptDir/_thmbs/$client";
// Download source to temp file
$tempFile = tempnam(sys_get_temp_dir(), 'img_');
$imgData = @file_get_contents($url);
if (!$imgData || file_put_contents($tempFile, $imgData) === false) {
header('HTTP/1.1 502 Bad Gateway');
exit(json_encode(['error' => 'Failed to download image.']));
}
// Validate image
$info = @getimagesize($tempFile);
if (!$info) {
unlink($tempFile);
header('HTTP/1.1 415 Unsupported Media Type');
exit(json_encode(['error' => 'Downloaded file is not a valid image.']));
}
list($origW, $origH, $type) = $info;
// Ensure AVIF constant
if (!defined('IMAGETYPE_AVIF')) define('IMAGETYPE_AVIF', 19);
// Convert and save original as JPEG
if (class_exists('Imagick')) {
try {
$imOrig = new Imagick($tempFile);
$imOrig->setImageFormat('jpeg');
$imOrig->writeImage($origPath);
$imOrig->destroy();
} catch (Exception $e) {
// fallback to GD
}
}
// Determine base filename
$path = parse_url($url, PHP_URL_PATH);
$urlBase = pathinfo($path, PATHINFO_FILENAME);
$base = $customName
? preg_replace('/[^a-zA-Z0-9_-]/', '', $customName)
: $urlBase;
$mimeExtMap = [
IMAGETYPE_JPEG=>'jpg',IMAGETYPE_PNG=>'png',IMAGETYPE_GIF=>'gif',
IMAGETYPE_WEBP=>'webp',IMAGETYPE_BMP=>'bmp', IMAGETYPE_AVIF => 'avif'
];
$origExt = $mimeExtMap[$type] ?? 'img';
$origFilename = "$base.$origExt";
// Save original in client folder
copy($tempFile, "$originalFolder/$origFilename");
// Prepare thumbnail filename (JPEG)
$thumbFilename = $base . "_{$thumbWidth}x{$thumbHeight}.jpg";
$thumbPath = "$thumbnailFolder/$thumbFilename";
// JSON error helper
function errorJson($msg, $code=500) {
http_response_code($code);
exit(json_encode(['error'=>$msg]));
}
// Generate thumbnail (Imagick if available)
if (class_exists('Imagick')) {
try {
$im = new Imagick($tempFile);
$im->thumbnailImage($thumbWidth, $thumbHeight, true);
$w = $im->getImageWidth();
$h = $im->getImageHeight();
$canvas = new Imagick();
$canvas->newImage($thumbWidth, $thumbHeight, new ImagickPixel('white'));
$canvas->compositeImage($im, Imagick::COMPOSITE_OVER, ($thumbWidth-$w)/2, ($thumbHeight-$h)/2);
$canvas->setImageFormat('jpeg');
$canvas->writeImage($thumbPath);
$im->destroy(); $canvas->destroy(); unlink($tempFile);
header('Content-Type:application/json');
exit(json_encode(['original'=>"$origBaseURL/$origFilename", 'thumbnail'=>"$thumbBaseURL/$thumbFilename"]));
} catch (Exception $e) {
unlink($tempFile);
errorJson('Imagick error: '.$e->getMessage());
}
}
// Fallback to GD
switch ($type) {
case IMAGETYPE_JPEG: $src=imagecreatefromjpeg($tempFile); break;
case IMAGETYPE_PNG: $src=imagecreatefrompng($tempFile); break;
case IMAGETYPE_GIF: $src=imagecreatefromgif($tempFile); break;
case IMAGETYPE_WEBP:
if (!function_exists('imagecreatefromwebp')) errorJson('WebP not supported');
$src=imagecreatefromwebp($tempFile); break;
case IMAGETYPE_BMP:
if (!function_exists('imagecreatefrombmp')) errorJson('BMP not supported');
$src=imagecreatefrombmp($tempFile); break;
case IMAGETYPE_AVIF:
if (!function_exists('imagecreatefromavif')) errorJson('AVIF not supported');
$src=imagecreatefromavif($tempFile); break;
default:
unlink($tempFile);
errorJson('Unsupported image format', 415);
}
// Create white canvas and prepare thumbnail
// Initialize a white background canvas of size {$thumbWidth}�--{$thumbHeight}
$thumb = imagecreatetruecolor($thumbWidth, $thumbHeight);
$whiteColor = imagecolorallocate($thumb, 255, 255, 255);
imagefilledrectangle(
$thumb, // destination image
0, 0, // top-left corner
$thumbWidth, // width
$thumbHeight,// height
$whiteColor // fill color
);
// Calculate aspect ratio to fit the original image into the square canvas
$ratio = min($thumbWidth / $origW, $thumbHeight / $origH);
$newW = (int) ($origW * $ratio);
$newH = (int) ($origH * $ratio);
// Calculate centering offsets
$offsetX = (int) (($thumbWidth - $newW) / 2);
$offsetY = (int) (($thumbHeight - $newH) / 2);
// Copy and resize original onto the canvas
imagecopyresampled(
$thumb, // destination
$src, // source
$offsetX, // dest x
$offsetY, // dest y
0, // src x
0, // src y
$newW, // dest width
$newH, // dest height
$origW, // src width
$origH // src height
);
// Save JPEG thumbnail
imagejpeg($thumb,$thumbPath,90);
// Cleanup
imagedestroy($src);
imagedestroy($thumb);
unlink($tempFile);
// return JSON
header('Content-Type:application/json');
echo json_encode([
'original'=>"$origBaseURL/$origFilename",
'thumbnail'=>"$thumbBaseURL/$thumbFilename"
]);
?>

Usage: Zoho Deluge
Awesome right?!? OpenAI ChatGPT made this for me in under an hour. I haven't properly tested whether it can manage *.webp and *.heic files but if I don't update this article after my further testing today then all good. I now needed to use a Deluge script to loop through all the products (in this case a "Models" table), download the product image, generate a thumbnail, and upload the thumbnail to the same record but to a field called "Thumbnail_Photo". Unfortunately, ChatGPT couldn't generate the ZohoDeluge script for me, so this is my script to do this. You will need to modify it as per your requirements. Here are 2 code snippets: the first is a function which will make a request to my online 'Thumbnailer' PHP script and the second is a function which will loop through the products table to generate and upload thumbnails:

copy raw

string API.fn_GenerateThumbnail(string p_ImageURL, string p_OutputName)
{
	/* *******************************************************************************
	Function:       string API.fn_GenerateThumbnail(string p_ImageURL, string p_OutputName)
	Label:          fn_GenerateThumbnail
	Trigger:        used primarily in workflow when product image is uploaded to generate a thumbnail
	Purpose:		Given an image on a public URL, converts the image to a thumbnail
	Inputs:         string p_ImageURL, string p_OutputName
	Outputs:        JSON of uploaded image URL and thumbnail URL

	Date Created:   2025-05-28 (Joel Lipman)
					- Initial release
	Date Modified:	???
					- ???

	More Information:
					- Accepts via GET:
					- - 'url'    (image URL, required)
					- - 'name'   (custom base filename, optional)
 					- - 'auth'   (API key, required; must match md5(internal_auth_key_1 . internal_auth_key_2 . the_client_name . date('d-M-Y')))
					- - 'client' (client identifier, required; lowercase, alphanumeric, hyphens/underscores)
 					
					- I use any online tool that generates random strings of 64 characters with symbols 
					  and numbers and enter these as the 2 keys used for authentication.  Make sure these 
					  match the ones within the PHP script or build an authentication process.  I don't 
					  have to go over the top with this one as it's a closed API used only by myself and 
					  colleagues so client name in the authentication with an MD5 hash will make this
					  unique per client.

	******************************************************************************* */
	//
	// TEST IMAGE URL: https://picsum.photos/400
	v_Client = "lowercase_url_safe_string_of_the_client_name";
	v_Key1 = "just_some_random_key_about_64_characters_long_of_alphanumeric_and_symbols";
	v_Key2 = "another_random_key_about_64_characters_long_of_alphanumeric_and_symbols";
	v_Key = zoho.encryption.md5(v_Key1 + v_Key2 + v_Client + zoho.currentdate.toString("dd-MMM-yyyy"));
	//
	m_Params = Map();
	m_Params.put("url",p_ImageURL);
	m_Params.put("name",p_OutputName);
	m_Params.put("auth",v_Key);
	m_Params.put("client",v_Client);
	//
	v_ThumbnailURL = invokeurl
	[
		url :"<URL_to_the_PHP_script_made_above>.php"
		type :GET
		parameters:m_Params
	];
	return v_ThumbnailURL;
}

string API.fn_GenerateThumbnail(string p_ImageURL, string p_OutputName)
{
/* *******************************************************************************
Function: string API.fn_GenerateThumbnail(string p_ImageURL, string p_OutputName)
Label: fn_GenerateThumbnail
Trigger: used primarily in workflow when product image is uploaded to generate a thumbnail
Purpose: Given an image on a public URL, converts the image to a thumbnail
Inputs: string p_ImageURL, string p_OutputName
Outputs: JSON of uploaded image URL and thumbnail URL
Date Created: 2025-05-28 (Joel Lipman)
- Initial release
Date Modified: ???
- ???
More Information:
- Accepts via GET:
- - 'url' (image URL, required)
- - 'name' (custom base filename, optional)
- - 'auth' (API key, required; must match md5(internal_auth_key_1 . internal_auth_key_2 . the_client_name . date('d-M-Y')))
- - 'client' (client identifier, required; lowercase, alphanumeric, hyphens/underscores)
- I use any online tool that generates random strings of 64 characters with symbols
and numbers and enter these as the 2 keys used for authentication. Make sure these
match the ones within the PHP script or build an authentication process. I don't
have to go over the top with this one as it's a closed API used only by myself and
colleagues so client name in the authentication with an MD5 hash will make this
unique per client.
******************************************************************************* */
//
// TEST IMAGE url: https://picsum.photos/400
v_Client = "lowercase_url_safe_string_of_the_client_name";
v_Key1 = "just_some_random_key_about_64_characters_long_of_alphanumeric_and_symbols";
v_Key2 = "another_random_key_about_64_characters_long_of_alphanumeric_and_symbols";
v_Key = zoho.encryption.md5(v_Key1 + v_Key2 + v_Client + zoho.currentdate.toString("dd-MMM-yyyy"));
//
m_Params = Map();
m_Params.put("url",p_ImageURL);
m_Params.put("name",p_OutputName);
m_Params.put("auth",v_Key);
m_Params.put("client",v_Client);
//
v_ThumbnailURL = invokeUrl
[
url :"<URL_to_the_PHP_script_made_above>.php"
type :GET
parameters:m_Params
];
return v_ThumbnailURL;
}

Now I can reuse this function whenever I want a JSON returned containing the URL of the thumbnail:

copy raw

void API.fn_GenerateModelThumbnails()
{
	/* *******************************************************************************
	Function:       void API.fn_GenerateModelThumbnails()
	Label:          fn_GenerateModelThumbnails
	Trigger:        standalone / on-demand
	Purpose:		Generate a thumbnail photo for all model/product records
	Inputs:         NONE
	Outputs:        Uploads thumbnail image to each record

	Date Created:   2025-05-28 (Joel Lipman)
					- Initial release
	Date Modified:	2025-06-05 (Joel Lipman)
					- Downloads and uploads the image not as a link URL to the thumbnailer but image stored in ZohoCreator
	Date Modified:	2025-06-11 (Joel Lipman)
					- Tweaks following production release
	******************************************************************************* */
	// init
	v_CountTotal = 0;
	v_CountSuccessful = 0;
	//
	l_Pages = {1,2};
	v_PerPage = 1;
	for each v_Page in l_Pages
    {
		//
		// calculate pagination and index ranges
		v_StartIndex = (v_Page-1) * v_PerPage;
		v_EndIndex = v_StartIndex + v_PerPage - 1;
		info "Page #" + v_Page + ": from " + v_StartIndex + " to " + v_EndIndex;
		//
		// select models/product records to loop through (modified ascending for the first pass, then modified descending going forwards)
		l_Models = Models[Photo != null && Thumbnail_Photo == null] sort by Modified_Time asc range from v_StartIndex to v_EndIndex;
		for each  c_Model in l_Models
		{
			//
			// increment counter
			v_CountTotal = v_CountTotal + 1;
			//
			// build up filename (unique?)
			l_ItemNameParts = List();
			if(!isBlank(c_Model.Model))
			{
				l_ItemNameParts.add(c_Model.Model);
			}
			if(!isBlank(c_Model.Brand))
			{
				l_ItemNameParts.add(c_Model.Brand);
			}
			if(!isBlank(c_Model.Club_Type))
			{
				l_ItemNameParts.add(c_Model.Club_Type);
			}
			v_ItemName = l_ItemNameParts.toString("-");
			info v_ItemName;
			//
			// this will be the filename of the image
			v_ItemNameSafe = v_ItemName.toLowerCase().replaceAll("[^a-z0-9]","-",false);
			//
			// removing consecutive hyphens/dashes
			v_ItemNameSafe = v_ItemNameSafe.replaceAll("--","-",true);
			v_ItemNameSafe = v_ItemNameSafe.replaceAll("--","-",true);
			//
			// check that there is an image file to begin with (field: Photo)
			v_ImgFileField = ifnull(c_Model.Photo,"");
			if(v_ImgFileField.contains("\""))
			{
				//
				// parse out the file name
				v_ImageSrc = v_ImgFileField.getSuffix("\"");
				v_ImageSrc = v_ImageSrc.getPrefix("\"");
				l_ImageSrcParts = v_ImageSrc.toList("/");
				v_ImageFilename = l_ImageSrcParts.get(l_ImageSrcParts.size() - 1);
				info v_ImageFilename;
				//
				// parse out the extension from the filename
				l_ImageFilenameParts = v_ImageFilename.toList(".");
				v_ImageExtension = l_ImageFilenameParts.get(l_ImageFilenameParts.size() - 1);
				info v_ImageExtension;
				//
				// now get public image url of this Photo field
				v_PublishKey = "<your_own_key_when_you_publish_the_report>";
				v_ModelPhotoURL = "https://creatorexport.zoho.com/file" + zoho.appuri + "All_Models_Public/" + c_Model.ID + "/Photo/image-download/" + v_PublishKey + "?filepath=" + v_ImageFilename;
				//
				// go go thumbnailer
				try
				{
					r_NewThumbnail = thisapp.API.fn_GenerateThumbnail(v_ModelPhotoURL,v_ItemNameSafe);
				}
				catch (e) 
				{
					r_NewThumbnail = Map();
					info "Thumbnailer Service not available";
					//
					// don't want to keep hammering the service if it's down
					return;
				}
				//
				// convert JSON to a Zoho Map Variable
				m_NewThumbnail = r_NewThumbnail.toMap();
				//
				// check that thumbnail and not error was received
				if(!isNull(m_NewThumbnail.get("thumbnail")))
				{
					//
					// output to console just for debugging
					v_NewThumbnailUrl = r_NewThumbnail.toMap().get("thumbnail");
					info v_NewThumbnailUrl;
					//
					// upload to Zoho Creator image field on form (this only adds link to image field)
					//v_ImageUpload = "<img src='" + v_NewThumbnailUrl + "' />";
					//c_Model.Thumbnail_Photo=v_ImageUpload;
					//
					// download actual file to use as file object
					f_Download = invokeUrl
                    [
                    	url: v_NewThumbnailUrl
						type: GET
                    ];
					//
					// IMPORTANT! set param name to file
					f_Download.setParamName("file");
					//
					// upload actual file to Zoho Creator image field (now hosted by ZohoCreator)
					v_Endpoint = "https://www.zohoapis.com/creator/v2.1/data"+zoho.appuri+"report/All_Models/"+c_Model.ID+"/Thumbnail_Photo/upload?skip_workflow=[\"all\"]";
					r_Upload = invokeUrl
                    [
                    	url: v_Endpoint
						type: POST
						connection: "zcreator"
						files: f_Download
                    ];
					m_Data = ifnull(r_Upload.get("data"), Map());
					v_Message = ifnull(m_Data.get("message"),"ERROR");
					//
					// increment successful
					if(v_Message.containsIgnoreCase("File Uploaded Successfully"))
					{
						v_CountSuccessful = v_CountSuccessful + 1;
					}				
				}
				else
				{
					info "ERROR: Could not generate thumbnail.";
				}
				info "------------------------------";
			}
		}		
    } 
	info "Successfully processed " + v_CountSuccessful + " of " + v_CountTotal;
}

void API.fn_GenerateModelThumbnails()
{
/* *******************************************************************************
Function: void API.fn_GenerateModelThumbnails()
Label: fn_GenerateModelThumbnails
Trigger: standalone / on-demand
Purpose: Generate a thumbnail photo for all model/product records
Inputs: NONE
Outputs: Uploads thumbnail image to each record
Date Created: 2025-05-28 (Joel Lipman)
- Initial release
Date Modified: 2025-06-05 (Joel Lipman)
- Downloads and uploads the image not as a link URL to the thumbnailer but image stored in ZohoCreator
Date Modified: 2025-06-11 (Joel Lipman)
- Tweaks following production release
******************************************************************************* */
// init
v_CountTotal = 0;
v_CountSuccessful = 0;
//
l_Pages = {1,2};
v_PerPage = 1;
for each v_Page in l_Pages
{
//
// calculate pagination and index ranges
v_StartIndex = (v_Page-1) * v_PerPage;
v_EndIndex = v_StartIndex + v_PerPage - 1;
info "Page #" + v_Page + ": from " + v_StartIndex + " to " + v_EndIndex;
//
// select models/product records to loop through (modified ascending for the first pass, then modified descending going forwards)
l_Models = Models[Photo != null && Thumbnail_Photo == null] sort by Modified_Time asc range from v_StartIndex to v_EndIndex;
for each c_Model in l_Models
{
//
// increment counter
v_CountTotal = v_CountTotal + 1;
//
// build up filename (unique?)
l_ItemNameParts = List();
if(!isBlank(c_Model.Model))
{
l_ItemNameParts.add(c_Model.Model);
}
if(!isBlank(c_Model.Brand))
{
l_ItemNameParts.add(c_Model.Brand);
}
if(!isBlank(c_Model.Club_Type))
{
l_ItemNameParts.add(c_Model.Club_Type);
}
v_ItemName = l_ItemNameParts.toString("-");
info v_ItemName;
//
// this will be the filename of the image
v_ItemNameSafe = v_ItemName.toLowerCase().replaceAll("[^a-z0-9]","-",false);
//
// removing consecutive hyphens/dashes
v_ItemNameSafe = v_ItemNameSafe.replaceAll("--","-",true);
v_ItemNameSafe = v_ItemNameSafe.replaceAll("--","-",true);
//
// check that there is an image file to begin with (field: Photo)
v_ImgFileField = ifnull(c_Model.Photo,"");
if(v_ImgFileField.contains("\""))
{
//
// parse out the file name
v_ImageSrc = v_ImgFileField.getSuffix("\"");
v_ImageSrc = v_ImageSrc.getPrefix("\"");
l_ImageSrcParts = v_ImageSrc.toList("/");
v_ImageFilename = l_ImageSrcParts.get(l_ImageSrcParts.size() - 1);
info v_ImageFilename;
//
// parse out the extension from the filename
l_ImageFilenameParts = v_ImageFilename.toList(".");
v_ImageExtension = l_ImageFilenameParts.get(l_ImageFilenameParts.size() - 1);
info v_ImageExtension;
//
// now get public image url of this Photo field
v_PublishKey = "<your_own_key_when_you_publish_the_report>";
v_ModelPhotoURL = "https://creatorexport.zoho.com/file" + zoho.appuri + "All_Models_Public/" + c_Model.ID + "/Photo/image-download/" + v_PublishKey + "?filepath=" + v_ImageFilename;
//
// go go thumbnailer
try
{
r_NewThumbnail = thisapp.API.fn_GenerateThumbnail(v_ModelPhotoURL,v_ItemNameSafe);
}
catch (e)
{
r_NewThumbnail = Map();
info "Thumbnailer Service not available";
//
// don't want to keep hammering the service if it's down
return;
}
//
// convert JSON to a Zoho Map Variable
m_NewThumbnail = r_NewThumbnail.toMap();
//
// check that thumbnail and not error was received
if(!isNull(m_NewThumbnail.get("thumbnail")))
{
//
// output to console just for debugging
v_NewThumbnailUrl = r_NewThumbnail.toMap().get("thumbnail");
info v_NewThumbnailUrl;
//
// upload to Zoho Creator image field on form (this only adds link to image field)
//v_ImageUpload = "<img src='" + v_NewThumbnailUrl + "' />";
//c_Model.Thumbnail_Photo=v_ImageUpload;
//
// download actual file to use as file object
f_Download = invokeUrl
[
url: v_NewThumbnailUrl
type: GET
];
//
// IMPORTANT! set param name to file
f_Download.setParamName("file");
//
// upload actual file to Zoho Creator image field (now hosted by ZohoCreator)
v_Endpoint = "https://www.zohoapis.com/creator/v2.1/data"+zoho.appuri+"report/All_Models/"+c_Model.ID+"/Thumbnail_Photo/upload?skip_workflow=[\"all\"]";
r_Upload = invokeUrl
[
url: v_Endpoint
type: POST
connection: "zcreator"
files: f_Download
];
m_Data = ifnull(r_Upload.get("data"), Map());
v_Message = ifnull(m_Data.get("message"),"ERROR");
//
// increment successful
if(v_Message.containsIgnoreCase("File Uploaded Successfully"))
{
v_CountSuccessful = v_CountSuccessful + 1;
}
}
else
{
info "ERROR: Could not generate thumbnail.";
}
info "------------------------------";
}
}
}
info "Successfully processed " + v_CountSuccessful + " of " + v_CountTotal;
}