diff --git a/src/calibre/ebooks/pdf/image_writer.py b/src/calibre/ebooks/pdf/image_writer.py
index 0e84b59a7a..b4c2f07d96 100644
--- a/src/calibre/ebooks/pdf/image_writer.py
+++ b/src/calibre/ebooks/pdf/image_writer.py
@@ -98,20 +98,15 @@ class Image:  # {{{
                 path_or_bytes = f.read()
         self.img_data = path_or_bytes
         fmt, width, height = identify(path_or_bytes)
-        if width > 0 and height > 0 and fmt == 'jpeg':
-            self.fmt = fmt
-            self.width, self.height = width, height
-            self.cache_key = None
-        else:
-            self.img, self.fmt = image_and_format_from_data(path_or_bytes)
-            self.width, self.height = self.img.width(), self.img.height()
-            self.cache_key = self.img.cacheKey()
+        self.img, self.fmt = image_and_format_from_data(path_or_bytes)
+        self.width, self.height = self.img.width(), self.img.height()
+        self.cache_key = self.img.cacheKey()
 # }}}
 
 
 def draw_image_page(writer, img, preserve_aspect_ratio=True):
     if img.fmt == 'jpeg':
-        ref = writer.add_jpeg_image(img.img_data, img.width, img.height, img.cache_key)
+        ref = writer.add_jpeg_image(img.img_data, img.width, img.height, img.cache_key, depth=img.img.depth())
     else:
         ref = writer.add_image(img.img, img.cache_key)
     page_size = tuple(writer.page_size)
diff --git a/src/calibre/ebooks/pdf/render/serialize.py b/src/calibre/ebooks/pdf/render/serialize.py
index 5b2aafe4ce..ceab4d97c9 100644
--- a/src/calibre/ebooks/pdf/render/serialize.py
+++ b/src/calibre/ebooks/pdf/render/serialize.py
@@ -416,8 +416,8 @@ class PDFStream:
         self.objects.commit(r, self.stream)
         return r
 
-    def add_jpeg_image(self, img_data, w, h, cache_key=None):
-        return self.write_image(img_data, w, h, 32, dct=True)
+    def add_jpeg_image(self, img_data, w, h, cache_key=None, depth=32):
+        return self.write_image(img_data, w, h, depth, dct=True)
 
     def add_image(self, img, cache_key):
         ref = self.get_image(cache_key)