diff --git a/weasyprint/images.py b/weasyprint/images.py
index 58f96f9fc..74e43c2ca 100644
--- a/weasyprint/images.py
+++ b/weasyprint/images.py
@@ -93,8 +93,7 @@ def draw(self, stream, concrete_width, concrete_height, image_rendering):
         if self.width <= 0 or self.height <= 0:
             return
 
-        width, height = self.width, self.height
-        interpolate = 'true' if image_rendering == 'auto' else 'false'
+        interpolate = image_rendering == 'auto'
         ratio = 1
         if self._dpi:
             pt_to_in = 4 / 3 / 96
@@ -103,7 +102,7 @@ def draw(self, stream, concrete_width, concrete_height, image_rendering):
             dpi = max(self.width / width_inches, self.height / height_inches)
             if dpi > self._dpi:
                 ratio = self._dpi / dpi
-        image_name = stream.add_image(self, width, height, interpolate, ratio)
+        image_name = stream.add_image(self, interpolate, ratio)
 
         stream.transform(
             concrete_width, 0, 0, -concrete_height, 0, concrete_height)
@@ -116,7 +115,20 @@ def cache_image_data(self, data, filename=None, alpha=False):
             key = f'{self.id}{int(alpha)}{self._dpi or ""}'
             return LazyImage(self._cache, key, data)
 
-    def get_xobject(self, width, height, interpolate):
+    def get_x_object(self, interpolate, dpi_ratio):
+        if dpi_ratio == 1:
+            width, height = self.width, self.height
+        else:
+            thumbnail = Image.open(io.BytesIO(self.image_data.data))
+            width = max(1, int(round(self.width * dpi_ratio)))
+            height = max(1, int(round(self.height * dpi_ratio)))
+            thumbnail.thumbnail((width, height))
+            image_file = io.BytesIO()
+            thumbnail.save(
+                image_file, format=thumbnail.format, optimize=self.optimize)
+            width, height = thumbnail.width, thumbnail.height
+            self.image_data = self.cache_image_data(image_file.getvalue())
+
         if self.mode in ('RGB', 'RGBA'):
             color_space = '/DeviceRGB'
         elif self.mode in ('L', 'LA'):
@@ -134,7 +146,7 @@ def get_xobject(self, width, height, interpolate):
             'Height': height,
             'ColorSpace': color_space,
             'BitsPerComponent': 8,
-            'Interpolate': interpolate,
+            'Interpolate': 'true' if interpolate else 'false',
         })
 
         if self.format == 'JPEG':
@@ -176,7 +188,7 @@ def get_xobject(self, width, height, interpolate):
                 'Height': height,
                 'ColorSpace': '/DeviceGray',
                 'BitsPerComponent': 8,
-                'Interpolate': interpolate,
+                'Interpolate': 'true' if interpolate else 'false',
             })
         else:
             png_data = self._get_png_data(
diff --git a/weasyprint/pdf/__init__.py b/weasyprint/pdf/__init__.py
index 6bfb3ddd1..b0b060149 100644
--- a/weasyprint/pdf/__init__.py
+++ b/weasyprint/pdf/__init__.py
@@ -62,12 +62,19 @@ def _use_references(pdf, resources, images):
     for key, x_object in resources.get('XObject', {}).items():
         # Images
         if x_object is None:
-            x_object = images[key]
-            if x_object.number is not None:
+            image_data = images[key]
+            x_object = image_data['x_object']
+
+            if x_object is not None:
                 # Image already added to PDF
                 resources['XObject'][key] = x_object.reference
                 continue
 
+            image = image_data['image']
+            dpi_ratio = max(image_data['dpi_ratios'])
+            x_object = image.get_x_object(image_data['interpolate'], dpi_ratio)
+            image_data['x_object'] = x_object
+
         pdf.add_object(x_object)
         resources['XObject'][key] = x_object.reference
 
diff --git a/weasyprint/pdf/stream.py b/weasyprint/pdf/stream.py
index abb1e06a2..e2a126f4b 100644
--- a/weasyprint/pdf/stream.py
+++ b/weasyprint/pdf/stream.py
@@ -8,7 +8,6 @@
 from fontTools import subset
 from fontTools.ttLib import TTFont, TTLibError, ttFont
 from fontTools.varLib.mutator import instantiateVariableFont
-from PIL import Image
 
 from ..logger import LOGGER
 from ..matrix import Matrix
@@ -362,26 +361,20 @@ def add_group(self, x, y, width, height):
         self._x_objects[group.id] = group
         return group
 
-    def add_image(self, image, width, height, interpolate, ratio):
-        image_name = f'i{image.id}{width}{height}{interpolate}{ratio}'
+    def add_image(self, image, interpolate, ratio):
+        image_name = f'i{image.id}{int(interpolate)}'
         self._x_objects[image_name] = None  # Set by write_pdf
         if image_name in self._images:
             # Reuse image already stored in document
+            self._images[image_name]['dpi_ratios'].add(ratio)
             return image_name
 
-        if ratio != 1:
-            thumbnail = Image.open(io.BytesIO(image.image_data.data))
-            width = int(round(image.width * ratio))
-            height = int(round(image.height * ratio))
-            thumbnail.thumbnail((max(1, width), max(1, height)))
-            image_file = io.BytesIO()
-            thumbnail.save(
-                image_file, format=thumbnail.format, optimize=image.optimize)
-            width, height = thumbnail.width, thumbnail.height
-            image.image_data = image.cache_image_data(image_file.getvalue())
-
-        xobject = image.get_xobject(width, height, interpolate)
-        self._images[image_name] = xobject
+        self._images[image_name] = {
+            'image': image,
+            'interpolate': interpolate,
+            'dpi_ratios': {ratio},
+            'x_object': None,  # Set by write_pdf
+        }
         return image_name
 
     def add_pattern(self, x, y, width, height, repeat_width, repeat_height,