diff --git a/tools/export-seg-model.sh b/tools/export-seg-model.sh
index f08dfc0..5468390 100755
--- a/tools/export-seg-model.sh
+++ b/tools/export-seg-model.sh
@@ -17,7 +17,7 @@
 # (see the workspace manifest for why that backend was chosen), and it is what
 # makes the tiling option in `semantic.rs` the only route to more resolution.
 #
-# `imgsz=640` square rather than a rectangle matched to 3:2: one graph has to
+# `imgsz` square rather than a rectangle matched to 3:2: one graph has to
 # serve portrait, landscape, square crops and panoramas. A landscape-shaped
 # graph trades letterbox waste on 3:2 for worse waste on everything else.
 set -euo pipefail
@@ -27,21 +27,23 @@ REPO="$(cd "${HERE}/.." && pwd)"
 OUT="${REPO}/core/dr-segment/models"
 
 MODEL="${1:-yolo26n-seg}"
+IMGSZ="${2:-640}"
 WORK="$(mktemp -d)"
 trap 'rm -rf "${WORK}"' EXIT
 
-echo "==> exporting ${MODEL} in ${WORK}"
+echo "==> exporting ${MODEL} at imgsz=${IMGSZ} in ${WORK}"
 cd "${WORK}"
 uv venv --python 3.12 venv
 VIRTUAL_ENV="${WORK}/venv" uv pip install ultralytics onnx onnxslim
 
-VIRTUAL_ENV="${WORK}/venv" "${WORK}/venv/bin/python" - "${MODEL}" <<'PY'
+VIRTUAL_ENV="${WORK}/venv" "${WORK}/venv/bin/python" - "${MODEL}" "${IMGSZ}" <<'PY'
 import sys, json
 from ultralytics import YOLO
 
 name = sys.argv[1]
+imgsz = int(sys.argv[2])
 m = YOLO(f"{name}.pt")
-path = m.export(format="onnx", opset=17, simplify=True, imgsz=640, dynamic=False)
+path = m.export(format="onnx", opset=17, simplify=True, imgsz=imgsz, dynamic=False)
 print("ONNX:", path)
 
 # The class names travel with the model rather than being retyped into Rust —