diff --git a/cista/preview.py b/cista/preview.py
index 8e88dc8..524fd81 100644
--- a/cista/preview.py
+++ b/cista/preview.py
@@ -1,11 +1,14 @@
 import asyncio
 import io
+import urllib.parse
 from pathlib import PurePosixPath
 from urllib.parse import unquote
+from wsgiref.handlers import format_date_time
 
+import fitz  # PyMuPDF
 from PIL import Image
-from sanic import Blueprint, raw
-from sanic.exceptions import Forbidden, NotFound
+from sanic import Blueprint, empty, raw
+from sanic.exceptions import NotFound
 from sanic.log import logger
 
 from cista import config
@@ -17,36 +20,68 @@ bp = Blueprint("preview", url_prefix="/preview")
 @bp.get("/<path:path>")
 async def preview(req, path):
     """Preview a file"""
-    width = int(req.query_string) if req.query_string else 1024
+    maxsize = int(req.args.get("px", 1024))
+    maxzoom = float(req.args.get("zoom", 2.0))
+    quality = int(req.args.get("q", 40))
     rel = PurePosixPath(sanitize(unquote(path)))
     path = config.config.path / rel
+    stat = path.lstat()
+    etag = config.derived_secret(
+        "preview", rel, stat.st_mtime_ns, quality, maxsize, maxzoom
+    ).hex()
+    savename = PurePosixPath(path.name).with_suffix(".webp")
+    headers = {
+        "etag": etag,
+        "last-modified": format_date_time(stat.st_mtime),
+        "cache-control": "max-age=604800, immutable",
+        "content-type": "image/webp",
+        "content-disposition": f"inline; filename*=UTF-8''{urllib.parse.quote(savename.as_posix())}",
+    }
+    if req.headers.if_none_match == etag:
+        # The client has it cached, respond 304 Not Modified
+        return empty(304, headers=headers)
+
     if not path.is_file():
         raise NotFound("File not found")
-    size = path.lstat().st_size
-    if size > 20 * 10**6:
-        raise Forbidden("File too large")
+
     img = await asyncio.get_event_loop().run_in_executor(
-        req.app.ctx.threadexec, process_image, path, width
+        req.app.ctx.threadexec, dispatch, path, quality, maxsize, maxzoom
     )
-    return raw(img, content_type="image/webp")
+    return raw(img, headers=headers)
 
 
-def process_image(path, maxsize):
+def dispatch(path, quality, maxsize, maxzoom):
+    if path.suffix.lower() in (".pdf", ".xps", ".epub", ".mobi"):
+        return process_pdf(path, quality=quality, maxsize=maxsize, maxzoom=maxzoom)
+    return process_image(path, quality=quality, maxsize=maxsize)
+
+
+def process_image(path, *, maxsize, quality):
     img = Image.open(path)
     w, h = img.size
     img.thumbnail((min(w, maxsize), min(h, maxsize)))
     # Fix rotation based on EXIF data
     try:
         rotate_values = {3: 180, 6: 270, 8: 90}
-        exif = img._getexif()
-        if exif:
-            orientation = exif.get(274)
-            if orientation in rotate_values:
-                logger.debug(f"Rotating preview {path} by {rotate_values[orientation]}")
-                img = img.rotate(rotate_values[orientation], expand=True)
+        orientation = img._getexif().get(274)
+        if orientation in rotate_values:
+            logger.debug(f"Rotating preview {path} by {rotate_values[orientation]}")
+            img = img.rotate(rotate_values[orientation], expand=True)
+    except AttributeError:
+        ...
     except Exception as e:
         logger.error(f"Error rotating preview image: {e}")
     # Save as webp
     imgdata = io.BytesIO()
-    img.save(imgdata, format="webp", quality=70, method=6)
+    img.save(imgdata, format="webp", quality=quality, method=4)
     return imgdata.getvalue()
+
+
+def process_pdf(path, *, maxsize, maxzoom, quality, page_number=0):
+    pdf = fitz.open(path)
+    page = pdf.load_page(page_number)
+    w, h = page.rect[2:4]
+    zoom = min(maxsize / w, maxsize / h, maxzoom)
+    mat = fitz.Matrix(zoom, zoom)
+    pix = page.get_pixmap(matrix=mat)
+    return pix.pil_tobytes(format="webp", quality=quality, method=4)
diff --git a/frontend/src/components/GalleryFigure.vue b/frontend/src/components/GalleryFigure.vue
index 1efbb46..1446581 100644
--- a/frontend/src/components/GalleryFigure.vue
+++ b/frontend/src/components/GalleryFigure.vue
@@ -10,7 +10,7 @@
   >
     <figure>
       <slot></slot>
-      <MediaPreview ref=m :doc="doc" :tabindex=-1 />
+      <MediaPreview ref=m :doc="doc" tabindex=-1 quality="?sz=512" />
       <caption>
         <label>
           <SelectBox :doc=doc />
diff --git a/frontend/src/components/MediaPreview.vue b/frontend/src/components/MediaPreview.vue
index 32ae7e3..beb6ecd 100644
--- a/frontend/src/components/MediaPreview.vue
+++ b/frontend/src/components/MediaPreview.vue
@@ -1,5 +1,6 @@
 <template>
-  <img v-if=doc.img :src="preview() ? doc.previewurl : doc.url" alt="">
+  <img v-if=preview() :src="`${doc.previewurl}?${quality}&t=${doc.mtime}`" alt="">
+  <img v-else-if=doc.img :src=doc.url alt="">
   <span v-else-if=doc.dir class="folder icon"></span>
   <video ref=vid v-else-if=video() :src=doc.url controls preload=none @click.prevent>📄</video>
   <audio ref=aud v-else-if=audio() :src=doc.url controls preload=metadata @click.stop>📄</audio>
@@ -16,6 +17,7 @@ const vid = ref<HTMLVideoElement | null>(null)
 const media = computed(() => aud.value || vid.value)
 const props = defineProps<{
   doc: Doc
+  quality: string
 }>()
 
 defineExpose({
@@ -34,8 +36,9 @@ const video = () => ['mkv', 'mp4', 'webm', 'mov', 'avi'].includes(props.doc.ext)
 const audio = () => ['mp3', 'flac', 'ogg', 'aac'].includes(props.doc.ext)
 const archive = () => ['zip', 'tar', 'gz', 'bz2', 'xz', '7z', 'rar'].includes(props.doc.ext)
 const preview = () => (
+  ['bmp', 'ico', 'tif', 'tiff', 'pdf'].includes(props.doc.ext) ||
   props.doc.size > 500000 &&
-  ['png', 'bmp', 'ico', 'webp', 'avif', 'jpg', 'jpeg'].includes(props.doc.ext)
+  ['avif', 'webp', 'png', 'jpg', 'jpeg'].includes(props.doc.ext)
 )
 </script>