diff --git a/pyproject.toml b/pyproject.toml
index 669ed0f3..2623d6a3 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -9,7 +9,7 @@ packages = [
     {include = "**/*.py", from = "src"},
 ]
 readme = "README.md"
-version = "0.28.0"
+version = "0.29.0"
 
 [tool.poetry.dependencies]
 # For certifi, use ">=" instead of "^" since it upgrades its "major version" every year, not really following semver
@@ -76,6 +76,7 @@ spaces_indent_inline_array = 4
 trailing_comma_inline_array = true
 
 [tool.pytest.ini_options]
+pythonpath = ["test"]
 markers = [
     "skip_for_edge_endpoint",
     "run_only_for_edge_endpoint",
diff --git a/src/groundlight/client.py b/src/groundlight/client.py
index 2318cab2..edcb8771 100644
--- a/src/groundlight/client.py
+++ b/src/groundlight/client.py
@@ -43,7 +43,7 @@
 from groundlight.binary_labels import Label, convert_internal_label_to_display
 from groundlight.config import API_TOKEN_MISSING_HELP_MESSAGE, API_TOKEN_VARIABLE_NAME, DISABLE_TLS_VARIABLE_NAME
 from groundlight.encodings import url_encode_dict
-from groundlight.images import ByteStreamWrapper, parse_supported_image_types
+from groundlight.images import ByteStreamWrapper, parse_supported_image_types, shrink_image_if_needed
 from groundlight.internalapi import (
     GroundlightApiClient,
     NotFoundError,
@@ -800,6 +800,11 @@ def submit_image_query(  # noqa: PLR0913 # pylint: disable=too-many-arguments, t
 
         image_bytesio: ByteStreamWrapper = parse_supported_image_types(image)
 
+        # Match the Groundlight cloud service's ingest pipeline locally. Saves bandwidth
+        # and ensures Edge Endpoints, which do not run this step, see the same input
+        # distribution cloud-trained models were trained on.
+        image_bytesio = ByteStreamWrapper(data=shrink_image_if_needed(image_bytesio.read()))
+
         params = {
             "detector_id": detector_id,
             "body": image_bytesio,
diff --git a/src/groundlight/images.py b/src/groundlight/images.py
index a8d2714f..d618144c 100644
--- a/src/groundlight/images.py
+++ b/src/groundlight/images.py
@@ -7,6 +7,15 @@
 
 DEFAULT_JPEG_QUALITY = 95
 
+# The Groundlight cloud service applies the same shrink-and-encode step on
+# ingest. Doing the same work client-side saves bandwidth and ensures Edge
+# Endpoints, which do not run this step, see the same input distribution that
+# cloud-trained models expect. Keep these constants in sync with the cloud
+# service if it ever changes its defaults.
+MAX_BYTES_IMAGE_SIZE = 256_000
+MAX_IMAGE_RESOLUTION_LONGSIDE = 1024
+SHRINK_JPEG_QUALITY = 85
+
 
 class ByteStreamWrapper(IOBase):
     """This class acts as a thin wrapper around bytes in order to
@@ -78,6 +87,28 @@ def bytestream_from_pil(pil_image: Image.Image, jpeg_quality: int = DEFAULT_JPEG
     return ByteStreamWrapper(data=bytesio)
 
 
+def shrink_image_if_needed(jpeg: bytes) -> bytes:
+    """Shrink an oversized JPEG to match the Groundlight cloud service's ingest pipeline.
+
+    If the input is already at or below MAX_BYTES_IMAGE_SIZE, returns it unchanged.
+    Otherwise, decodes the image, scales it (BICUBIC, aspect-ratio preserved) so the
+    longest side is at most MAX_IMAGE_RESOLUTION_LONGSIDE, and re-encodes as JPEG.
+
+    Already-lossy JPEGs are decoded and re-encoded, which is the same lossy step the
+    cloud has been doing for years; net quality reaching the ML pipeline is unchanged.
+    """
+    if len(jpeg) <= MAX_BYTES_IMAGE_SIZE:
+        return jpeg
+    img = Image.open(BytesIO(jpeg)).convert("RGB")
+    if max(img.size) > MAX_IMAGE_RESOLUTION_LONGSIDE:
+        ratio = MAX_IMAGE_RESOLUTION_LONGSIDE / max(img.size)
+        new_size = (int(img.width * ratio), int(img.height * ratio))
+        img = img.resize(new_size, resample=Image.Resampling.BICUBIC)
+    buf = BytesIO()
+    img.save(buf, "jpeg", quality=SHRINK_JPEG_QUALITY)
+    return buf.getvalue()
+
+
 def parse_supported_image_types(
     image: Union[str, bytes, Image.Image, BytesIO, BufferedReader, np.ndarray],
     jpeg_quality: int = 95,
diff --git a/test/integration/test_groundlight.py b/test/integration/test_groundlight.py
index c96f4ae9..63ddc84c 100644
--- a/test/integration/test_groundlight.py
+++ b/test/integration/test_groundlight.py
@@ -10,6 +10,7 @@
 import pytest
 from groundlight import Groundlight
 from groundlight.binary_labels import VALID_DISPLAY_LABELS, Label, convert_internal_label_to_display
+from groundlight.images import MAX_IMAGE_RESOLUTION_LONGSIDE
 from groundlight.internalapi import ApiException, NotFoundError
 from groundlight.optional_imports import *
 from groundlight.status_codes import is_user_error
@@ -29,6 +30,7 @@
 )
 from urllib3.exceptions import ConnectTimeoutError, MaxRetryError, ReadTimeoutError
 from urllib3.util.retry import Retry
+from utils import make_random_jpeg
 
 from test.retry_decorator import retry_on_failure
 
@@ -368,6 +370,25 @@ def test_submit_image_query_png(gl: Groundlight, detector: Detector):
     assert is_valid_display_result(_image_query.result)
 
 
+@retry_on_failure()
+def test_submit_image_query_shrinks_oversized_image(gl: Groundlight, detector: Detector):
+    """Verifies the SDK shrinks oversized images client-side and the cloud stores the shrunken version.
+
+    Detects drift between the SDK and the cloud service: if either side changes its
+    algorithm such that the cloud-stored dimensions differ from what the SDK produces
+    locally, this test fails. Does not catch the cloud service becoming more permissive
+    (the SDK would still shrink to a smaller image that the cloud accepts as-is); that
+    direction is benign and intentionally not covered.
+    """
+    # Random noise compresses poorly, so 4000x3000 is well above the 256 KB threshold.
+    big = make_random_jpeg(4000, 3000)
+
+    iq = gl.submit_image_query(detector=detector.id, image=big, human_review="NEVER")
+    stored = Image.open(gl.get_image(iq.id))
+    # 4000x3000 scaled so longest side == 1024 preserves the 4:3 aspect ratio.
+    assert stored.size == (MAX_IMAGE_RESOLUTION_LONGSIDE, 768)
+
+
 @retry_on_failure()
 def test_submit_image_query_with_confidence_threshold(gl: Groundlight, detector: Detector):
     confidence_threshold = 0.5234  # Arbitrary specific value
diff --git a/test/unit/test_image_submission.py b/test/unit/test_image_submission.py
new file mode 100644
index 00000000..0003dba1
--- /dev/null
+++ b/test/unit/test_image_submission.py
@@ -0,0 +1,30 @@
+"""Tests for image handling behavior in Groundlight.submit_image_query."""
+
+from io import BytesIO
+from unittest import mock
+
+import pytest
+from groundlight import Groundlight
+from groundlight.images import MAX_BYTES_IMAGE_SIZE, MAX_IMAGE_RESOLUTION_LONGSIDE
+from groundlight.internalapi import InternalApiError
+from PIL import Image
+from utils import make_random_jpeg
+
+
+def test_submit_image_query_sends_shrunken_image(gl: Groundlight):
+    """Verifies that image shrinking runs in the submission path by inspecting the bytes at the HTTP layer.
+
+    Submits an oversized image to a mocked urllib3 transport, then checks that the body
+    that actually went on the wire was already resized to the expected dimensions.
+    """
+    big = make_random_jpeg(4000, 3000)
+    assert len(big) > MAX_BYTES_IMAGE_SIZE
+
+    with mock.patch("urllib3.PoolManager.request") as mock_request:
+        mock_request.return_value.status = 500
+        with pytest.raises(InternalApiError):
+            gl.submit_image_query(detector="det_test", image=big, wait=0)
+
+    body = mock_request.call_args_list[0].kwargs["body"]
+    sent_img = Image.open(BytesIO(body))
+    assert max(sent_img.size) == MAX_IMAGE_RESOLUTION_LONGSIDE
diff --git a/test/unit/test_imagefuncs.py b/test/unit/test_imagefuncs.py
index 835aac1a..587b2fae 100644
--- a/test/unit/test_imagefuncs.py
+++ b/test/unit/test_imagefuncs.py
@@ -7,6 +7,7 @@
 import pytest
 from groundlight.images import *
 from groundlight.optional_imports import *
+from utils import make_random_jpeg
 
 JPEG_MIN_SIZE = 500
 
@@ -90,6 +91,36 @@ def test_pil_support_ref():
         assert img2.size == (509, 339)
 
 
+def test_shrink_image_if_needed_small_returns_unchanged():
+    """Images at or below the byte threshold are passed through untouched."""
+    small = make_random_jpeg(200, 200)
+    assert len(small) <= MAX_BYTES_IMAGE_SIZE
+    assert shrink_image_if_needed(small) is small
+
+
+def test_shrink_image_if_needed_oversized_dimensions_get_resized():
+    """Images above the byte threshold with longest side > 1024 are downscaled."""
+    # Random noise compresses poorly, so 4000x3000 easily exceeds the 256 KB threshold.
+    big = make_random_jpeg(4000, 3000)
+    assert len(big) > MAX_BYTES_IMAGE_SIZE
+    out = shrink_image_if_needed(big)
+    out_img = Image.open(BytesIO(out))
+    # 4000x3000 scaled so longest side == 1024 preserves the 4:3 aspect ratio.
+    assert out_img.size == (1024, 768)
+
+
+def test_shrink_image_if_needed_oversized_bytes_only_gets_reencoded():
+    """Images above the byte threshold but with longest side <= 1024 are re-encoded only."""
+    high_q = make_random_jpeg(1024, 768, quality=99)
+    assert len(high_q) > MAX_BYTES_IMAGE_SIZE
+    out = shrink_image_if_needed(high_q)
+    out_img = Image.open(BytesIO(out))
+    assert out_img.size == (1024, 768)
+    # Bytes changed (proves re-encode happened) and got smaller (Q85 vs Q99).
+    assert out != high_q
+    assert len(out) < len(high_q)
+
+
 def test_byte_stream_wrapper():
     """
     Test that we can call `open` and `close` repeatedly many times on a
diff --git a/test/utils.py b/test/utils.py
new file mode 100644
index 00000000..4178052d
--- /dev/null
+++ b/test/utils.py
@@ -0,0 +1,14 @@
+"""Shared utility functions for tests."""
+
+import os
+from io import BytesIO
+
+from PIL import Image
+
+
+def make_random_jpeg(width: int, height: int, quality: int = 95) -> bytes:
+    """Generate a JPEG with random pixel data."""
+    img = Image.frombytes("RGB", (width, height), os.urandom(width * height * 3))
+    buf = BytesIO()
+    img.save(buf, "jpeg", quality=quality)
+    return buf.getvalue()