diff --git a/config/services.yaml b/config/services.yaml
index 9113951..7edcc9c 100644
--- a/config/services.yaml
+++ b/config/services.yaml
@@ -82,10 +82,14 @@ services:
         class: Sigwin\YASSG\Bridge\Symfony\HttpKernel\Fragment\RelativeUrlInlineFragmentRenderer
         decorates: fragment.renderer.inline
 
-    sigwin_yassg.file_decoder.caching_file_decoder:
+    sigwin_yassg.file_decoder.thumbnail_queue_file_decoder:
         class: Sigwin\YASSG\Decoder\CachingFileDecoder
         decorates: 'Sigwin\YASSG\FileDecoder'
-
+        decoration_priority: 200
+    sigwin_yassg.file_decoder.caching_file_decoder:
+        class: Sigwin\YASSG\Decoder\ThumbnailQueueFileDecoder
+        decorates: 'Sigwin\YASSG\FileDecoder'
+        decoration_priority: 100
     Sigwin\YASSG\FileDecoder:
         class: Sigwin\YASSG\Decoder\CompositeFileDecoder
         arguments:
diff --git a/psalm.baseline.xml b/psalm.baseline.xml
index b23f625..748a7d3 100644
--- a/psalm.baseline.xml
+++ b/psalm.baseline.xml
@@ -407,6 +407,19 @@
       <code>PaginatorExtension</code>
     </UnusedClass>
   </file>
+  <file src="src/Bridge/Twig/Extension/ThumbnailExtension.php">
+    <MixedArgument>
+      <code><![CDATA[$GLOBALS['YASSG_BASEDIR']]]></code>
+      <code><![CDATA[$context['_path']]]></code>
+    </MixedArgument>
+    <PossiblyUndefinedStringArrayOffset>
+      <code><![CDATA[$GLOBALS['YASSG_BASEDIR']]]></code>
+      <code><![CDATA[$context['_path']]]></code>
+    </PossiblyUndefinedStringArrayOffset>
+    <UnusedClass>
+      <code>ThumbnailExtension</code>
+    </UnusedClass>
+  </file>
   <file src="src/Collection.php">
     <PossiblyUnusedMethod>
       <code>column</code>
@@ -536,7 +549,16 @@
       <code>MarkdownFileDecoder</code>
     </UnusedClass>
   </file>
+  <file src="src/Decoder/ThumbnailQueueFileDecoder.php">
+    <UnusedClass>
+      <code>ThumbnailQueueFileDecoder</code>
+    </UnusedClass>
+  </file>
   <file src="src/Decoder/YamlFileDecoder.php">
+    <MixedReturnTypeCoercion>
+      <code>$data</code>
+      <code>array</code>
+    </MixedReturnTypeCoercion>
     <UnusedClass>
       <code>YamlFileDecoder</code>
     </UnusedClass>
@@ -648,6 +670,11 @@
       <code>array</code>
     </PossiblyUnusedReturnValue>
   </file>
+  <file src="src/ThumbnailQueue.php">
+    <PossiblyUnusedMethod>
+      <code>__construct</code>
+    </PossiblyUnusedMethod>
+  </file>
   <file src="tests/functional/site/src/Bridge/Symfony/EventSubscriber.php">
     <UnusedClass>
       <code>EventSubscriber</code>
diff --git a/src/Bridge/Twig/Extension/ThumbnailExtension.php b/src/Bridge/Twig/Extension/ThumbnailExtension.php
new file mode 100644
index 0000000..39e05b0
--- /dev/null
+++ b/src/Bridge/Twig/Extension/ThumbnailExtension.php
@@ -0,0 +1,47 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Sigwin Yassg project.
+ *
+ * (c) sigwin.hr
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Sigwin\YASSG\Bridge\Twig\Extension;
+
+use Sigwin\YASSG\ThumbnailQueue;
+use Symfony\Component\Asset\Packages;
+use Twig\Extension\AbstractExtension;
+use Twig\TwigFunction;
+
+final class ThumbnailExtension extends AbstractExtension
+{
+    public function __construct(private readonly Packages $packages, private readonly ThumbnailQueue $thumbnailQueue) {}
+
+    public function getFunctions(): array
+    {
+        return [
+            new TwigFunction('yassg_thumbnail', function (array $context, string $path): string {
+                if (str_starts_with($path, './')) {
+                    $newPath = realpath(\dirname($context['_path']).'/'.$path);
+                    if ($newPath === false) {
+                        throw new \RuntimeException('Invalid thumbnail path '.$path);
+                    }
+                    $path = $newPath;
+                }
+
+                $relative = str_replace($GLOBALS['YASSG_BASEDIR'], '', $path);
+                $this->thumbnailQueue->add([
+                    'source' => $path,
+                    'destination' => $relative,
+                ]);
+
+                return $this->packages->getUrl(ltrim($relative, '/'));
+            }, ['needs_context' => true]),
+        ];
+    }
+}
diff --git a/src/Decoder/CachingFileDecoder.php b/src/Decoder/CachingFileDecoder.php
index b7d2b28..b234f62 100644
--- a/src/Decoder/CachingFileDecoder.php
+++ b/src/Decoder/CachingFileDecoder.php
@@ -37,7 +37,7 @@ public function decode(\SplFileInfo $file): array
 
         $item = $this->cachePoolItem->getItem($key);
         if ($item->isHit()) {
-            /** @var array $value */
+            /** @var array<string, string> $value */
             $value = $item->get();
 
             return $value;
diff --git a/src/Decoder/MarkdownFileDecoder.php b/src/Decoder/MarkdownFileDecoder.php
index c999b21..f230938 100644
--- a/src/Decoder/MarkdownFileDecoder.php
+++ b/src/Decoder/MarkdownFileDecoder.php
@@ -16,6 +16,7 @@
 use League\CommonMark\ConverterInterface;
 use League\CommonMark\Extension\FrontMatter\FrontMatterProviderInterface;
 use Sigwin\YASSG\FileDecoder;
+use Sigwin\YASSG\ThumbnailQueue;
 use Symfony\Component\Yaml\Exception\ParseException;
 use Symfony\Component\Yaml\Yaml;
 use Twig\Environment;
@@ -26,7 +27,7 @@
 
     private const EXTENSIONS = ['md', 'markdown'];
 
-    public function __construct(private ConverterInterface $converter, private Environment $twig) {}
+    public function __construct(private ConverterInterface $converter, private Environment $twig, private ThumbnailQueue $thumbnailQueue) {}
 
     public function decode(\SplFileInfo $file): array
     {
@@ -41,6 +42,7 @@ public function decode(\SplFileInfo $file): array
         }
 
         $metadata = [];
+        $thumbnails = [];
         if (str_contains($content, '{{') || str_contains($content, '{%')) {
             if (str_starts_with($content, '---')) {
                 $end = mb_strpos($content, '---', 3);
@@ -59,7 +61,9 @@ public function decode(\SplFileInfo $file): array
 
             $content = $this->twig->createTemplate($content)->render([
                 'item' => $metadata,
+                '_path' => $file->getPathname(),
             ]);
+            $thumbnails = $this->thumbnailQueue->flush();
         }
 
         $result = $this->converter->convert($content);
@@ -68,6 +72,7 @@ public function decode(\SplFileInfo $file): array
             $metadata = $result->getFrontMatter();
         }
         $metadata['body'] = $result->getContent();
+        $metadata['@thumbnails'] = $thumbnails;
 
         return $metadata;
     }
diff --git a/src/Decoder/ThumbnailQueueFileDecoder.php b/src/Decoder/ThumbnailQueueFileDecoder.php
new file mode 100644
index 0000000..03fca71
--- /dev/null
+++ b/src/Decoder/ThumbnailQueueFileDecoder.php
@@ -0,0 +1,45 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Sigwin Yassg project.
+ *
+ * (c) sigwin.hr
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Sigwin\YASSG\Decoder;
+
+use Sigwin\YASSG\FileDecoder;
+use Sigwin\YASSG\ThumbnailQueue;
+
+/**
+ * @psalm-import-type TThumbnailOptions from \Sigwin\YASSG\ThumbnailQueue
+ */
+final readonly class ThumbnailQueueFileDecoder implements FileDecoder
+{
+    public function __construct(private FileDecoder $decoder, private ThumbnailQueue $thumbnailQueue) {}
+
+    public function supports(\SplFileInfo $file): bool
+    {
+        return $this->decoder->supports($file);
+    }
+
+    public function decode(\SplFileInfo $file): array
+    {
+        /** @var array{"@thumbnails"?: list<TThumbnailOptions>} $decoded */
+        $decoded = $this->decoder->decode($file);
+
+        if (isset($decoded['@thumbnails'])) {
+            foreach ($decoded['@thumbnails'] as $thumbnail) {
+                $this->thumbnailQueue->add($thumbnail);
+            }
+        }
+        unset($decoded['@thumbnails']);
+
+        return $decoded;
+    }
+}
diff --git a/src/FileDecoder.php b/src/FileDecoder.php
index 637c310..3815e65 100644
--- a/src/FileDecoder.php
+++ b/src/FileDecoder.php
@@ -17,5 +17,8 @@ interface FileDecoder
 {
     public function supports(\SplFileInfo $file): bool;
 
+    /**
+     * @return array<string, mixed>
+     */
     public function decode(\SplFileInfo $file): array;
 }
diff --git a/src/Generator.php b/src/Generator.php
index 3542aba..65a1f0e 100644
--- a/src/Generator.php
+++ b/src/Generator.php
@@ -28,8 +28,13 @@
  */
 final readonly class Generator
 {
-    public function __construct(private string $buildDir, private Permutator $permutator, private UrlGeneratorInterface $urlGenerator, private KernelInterface $kernel, private Filesystem $filesystem) {}
+    public function __construct(private string $buildDir, private Permutator $permutator, private UrlGeneratorInterface $urlGenerator, private KernelInterface $kernel, private Filesystem $filesystem, private ThumbnailQueue $thumbnailQueue) {}
 
+    /**
+     * @param callable(Request, Response, string): void $callable
+     *
+     * @throws \Exception
+     */
     public function generate(callable $callable): void
     {
         $requestContext = $this->urlGenerator->getContext();
@@ -71,6 +76,10 @@ public function generate(callable $callable): void
 
             $response = $this->dumpRequest($callable, $request);
             $urlSet->addUrl(new UrlConcrete($url, new \DateTimeImmutable($response->headers->get('Last-Modified', 'now'))));
+
+            $this->thumbnailQueue->flush(function (array $item) use ($callable): void {
+                $callable($this->createRequest($item['destination']), new Response('OK'), $item['destination']);
+            });
         }
         if ($urlSet !== null) {
             $this->dumpSitemap($urlSet, $deflate);
@@ -105,6 +114,11 @@ private function generateUrl(string $path): string
         return sprintf('%1$s://%2$s%3$s%4$s', $context->getScheme(), $context->getHost(), $context->getBaseUrl(), $path);
     }
 
+    /**
+     * @param callable(Request, Response, string): void $callable
+     *
+     * @throws \Exception
+     */
     private function dumpRequest(callable $callable, Request $request, int $expectedStatusCode = 200): Response
     {
         try {
diff --git a/src/ThumbnailQueue.php b/src/ThumbnailQueue.php
new file mode 100644
index 0000000..df44232
--- /dev/null
+++ b/src/ThumbnailQueue.php
@@ -0,0 +1,62 @@
+<?php
+
+declare(strict_types=1);
+
+/*
+ * This file is part of the Sigwin Yassg project.
+ *
+ * (c) sigwin.hr
+ *
+ * This source file is subject to the MIT license that is bundled
+ * with this source code in the file LICENSE.
+ */
+
+namespace Sigwin\YASSG;
+
+use Symfony\Component\Filesystem\Filesystem;
+
+/**
+ * @psalm-type TThumbnailOptions = array{source: string, destination: string}
+ */
+final class ThumbnailQueue
+{
+    /**
+     * @var array<string, TThumbnailOptions>
+     */
+    private array $queue = [];
+
+    public function __construct(private string $buildDir, private Filesystem $filesystem) {}
+
+    /**
+     * @param TThumbnailOptions $specification
+     */
+    public function add(array $specification): void
+    {
+        $this->queue[$specification['destination']] = $specification;
+    }
+
+    /**
+     * @param callable(TThumbnailOptions): void $callable
+     *
+     * @return list<TThumbnailOptions>
+     */
+    public function flush(?callable $callable = null): array
+    {
+        foreach ($this->queue as $specification) {
+            $destination = $this->buildDir.'/'.ltrim($specification['destination'], '/');
+            if (file_exists($destination)) {
+                continue;
+            }
+
+            // TODO: ImgProxy
+            $this->filesystem->copy($specification['source'], $destination);
+            if ($callable !== null) {
+                $callable($specification);
+            }
+        }
+        $queue = array_values($this->queue);
+        $this->queue = [];
+
+        return $queue;
+    }
+}
diff --git a/tests/functional/site/content/articles/images/image.webp b/tests/functional/site/content/articles/images/image.webp
new file mode 100644
index 0000000..57df74a
Binary files /dev/null and b/tests/functional/site/content/articles/images/image.webp differ
diff --git a/tests/functional/site/content/articles/images.md b/tests/functional/site/content/articles/images/images.md
similarity index 73%
rename from tests/functional/site/content/articles/images.md
rename to tests/functional/site/content/articles/images/images.md
index bfe9f69..00bad3d 100644
--- a/tests/functional/site/content/articles/images.md
+++ b/tests/functional/site/content/articles/images/images.md
@@ -2,7 +2,7 @@
 title: Images!
 slug: images
 publishedAt: "2022-07-20 12:35:00"
-image: assets/images/sigwin.svg
+image: ./image.webp
 ---
 
 | Column 1 | Column 2 | Column 3 |
@@ -13,7 +13,7 @@ image: assets/images/sigwin.svg
 
 This is a database lookup example: {{yassg_get('articles', '/hello-world.md').title}}
 
-This is an asset lookup: {{asset(item.image)}}
+This is an asset lookup: {{ yassg_thumbnail(item.image) }}
 
-![Logo]({{ asset(item.image) }})
+![Logo]({{ yassg_thumbnail(item.image) }})
 
diff --git a/tests/functional/site/fixtures/content/articles/images/image.webp b/tests/functional/site/fixtures/content/articles/images/image.webp
new file mode 100644
index 0000000..57df74a
Binary files /dev/null and b/tests/functional/site/fixtures/content/articles/images/image.webp differ
diff --git a/tests/functional/site/fixtures/en/article/images/index.html b/tests/functional/site/fixtures/en/article/images/index.html
index df7e3d6..83b5492 100644
--- a/tests/functional/site/fixtures/en/article/images/index.html
+++ b/tests/functional/site/fixtures/en/article/images/index.html
@@ -43,8 +43,8 @@ <h1>Images!</h1>
 </tbody>
 </table>
 <p>This is a database lookup example: Hello World!</p>
-<p>This is an asset lookup: /sub/dir/another/assets/images/sigwin.6f9a3d5b.svg</p>
-<p><img src="/sub/dir/another/assets/images/sigwin.6f9a3d5b.svg" alt="Logo" /></p>
+<p>This is an asset lookup: /sub/dir/another/content/articles/images/image.webp</p>
+<p><img src="/sub/dir/another/content/articles/images/image.webp" alt="Logo" /></p>
 
         </div>
     </div>