diff --git a/src/trame_rca/encoders/img.py b/src/trame_rca/encoders/img.py
index 7f45d74..512c546 100644
--- a/src/trame_rca/encoders/img.py
+++ b/src/trame_rca/encoders/img.py
@@ -1,3 +1,5 @@
+import numpy as np
+
 TO_IMAGE_TYPE = {
     "avif": "image/avif",
     "jpeg": "image/jpeg",
@@ -13,3 +15,24 @@
     "png": "png",
     "webp": "webp",
 }
+
+
+def rgbx_view(image):
+    """
+    Return the RGBX buffer behind an RGB view over 4-byte pixels, or None.
+    VtkRemoteControlledArea returns such a view so the encoders can skip a copy.
+    """
+    base = image.base
+    if (
+        image.dtype == np.uint8
+        and image.ndim == 3
+        and image.shape[2] == 3
+        and isinstance(base, np.ndarray)
+        and base.dtype == np.uint8
+        and base.flags.c_contiguous
+        and base.shape == (*image.shape[:2], 4)
+        and image.strides == base.strides
+        and image.ctypes.data == base.ctypes.data
+    ):
+        return base
+    return None
diff --git a/src/trame_rca/encoders/pil.py b/src/trame_rca/encoders/pil.py
index 9f4f99c..d1db731 100644
--- a/src/trame_rca/encoders/pil.py
+++ b/src/trame_rca/encoders/pil.py
@@ -4,7 +4,7 @@
 from numpy.typing import NDArray
 from PIL import Image
 
-from trame_rca.encoders.img import TO_IMAGE_FORMAT, TO_IMAGE_TYPE
+from trame_rca.encoders.img import TO_IMAGE_FORMAT, TO_IMAGE_TYPE, rgbx_view
 
 # Not supported on all platform so make it optional
 with suppress(ImportError):
@@ -54,7 +54,18 @@ def encode_np_img_to_bytes(
 
     # t0 = time.time()
     fake_file = BytesIO()
-    image = Image.fromarray(image)
+    rgbx = rgbx_view(image)
+    if rgbx is None:
+        # Copies: Pillow stores RGB as 4 bytes per pixel, so it can't share a
+        # 3-channel array
+        image = Image.fromarray(image)
+    else:
+        # VtkRemoteControlledArea frame: map its RGBX buffer without a copy
+        height, width = rgbx.shape[:2]
+        image = Image.frombuffer("RGBX", (width, height), rgbx, "raw", "RGBX", 0, 1)
+        if TO_IMAGE_FORMAT[img_format] != "jpeg":
+            # PNG can't write RGBX; this is the one copy fromarray would make
+            image = image.convert("RGB")
     image.save(fake_file, TO_IMAGE_FORMAT[img_format], quality=quality)
     # t1 = time.time()
     # print(f"pill encode {t1-t0:.04f}s")
diff --git a/src/trame_rca/encoders/turbo_jpeg.py b/src/trame_rca/encoders/turbo_jpeg.py
index 094033c..1b836b0 100644
--- a/src/trame_rca/encoders/turbo_jpeg.py
+++ b/src/trame_rca/encoders/turbo_jpeg.py
@@ -1,6 +1,6 @@
 from numpy.typing import NDArray
-from turbojpeg import TurboJPEG, TJPF_RGB
-from trame_rca.encoders.img import TO_IMAGE_TYPE
+from turbojpeg import TurboJPEG, TJPF_RGB, TJPF_RGBX, TJSAMP_420
+from trame_rca.encoders.img import TO_IMAGE_TYPE, rgbx_view
 # import time
 
 jpeg = TurboJPEG()
@@ -41,7 +41,13 @@ def encode_np_img_to_bytes(
         return b""
 
     # t0 = time.time()
-    result = jpeg.encode(image, quality=quality, pixel_format=TJPF_RGB)
+    pixel_format = TJPF_RGB
+    rgbx = rgbx_view(image)
+    if rgbx is not None:
+        image, pixel_format = rgbx, TJPF_RGBX
+    result = jpeg.encode(
+        image, quality=quality, pixel_format=pixel_format, jpeg_subsample=TJSAMP_420
+    )
     # t1 = time.time()
     # print(f"tubo-jpeg encode {t1-t0:.04f}s")
 
diff --git a/src/trame_rca/rca/vtk_rca.py b/src/trame_rca/rca/vtk_rca.py
index 534dcaa..06360e3 100644
--- a/src/trame_rca/rca/vtk_rca.py
+++ b/src/trame_rca/rca/vtk_rca.py
@@ -1,5 +1,6 @@
 import json
 
+import numpy as np
 import vtkmodules.vtkRenderingOpenGL2  # noqa
 from packaging.version import Version
 from trame_common.utils import profiler
@@ -27,6 +28,7 @@ def __init__(self, vtk_render_window: vtkRenderWindow):
         self._window_to_image.ReadFrontBufferOff()
         self._window_to_image.ShouldRerenderOff()
         self._window_to_image.FixBoundaryOn()
+        self._window_to_image.SetInputBufferTypeToRGBA()
 
     @property
     def img_cols_rows(self):
@@ -40,7 +42,10 @@ def img_cols_rows(self):
             scalars = image_data.GetPointData().GetScalars()
             np_image = vtk_to_numpy(scalars)
             np_image = np_image.reshape((rows, cols, -1))
-            np_image[:] = np_image[::-1, :, :]
+            # Flip into a new RGBA buffer and return its RGB channels as a view:
+            # VTK's alpha is 0 on the background, and the encoders can read the
+            # 4-byte pixels in place (see encoders.img.rgbx_view)
+            np_image = np.ascontiguousarray(np_image[::-1])[..., :3]
             return np_image, cols, rows
 
     @property