fix(detr): match reference resize rounding

[WenJing95]

Background

DETR resizes a 600x1200 image to 667x1333, while the reference produces 666x1333. This rejects inputs for an engine built at the reference dimensions.

Exit Criteria

Landscape and portrait inputs fit their reference-sized engine inputs.

Implementation

Round exact halves to the nearest even integer in the DETR preprocessor.

Change categories

• Model or runtime behavior

Validation

Commands and Results

Native regression passed (21 checks); source-quality passed (164 tests).

g++ -std=c++17 -Wall -Wextra -Wpedantic -Wno-missing-field-initializers -Wno-unused-function -I. -Ithird_party/stb families/detr/tests/cpp/test_image_preprocess_seam.cpp families/detr/runtime/image_preprocess_seam.cpp -o /tmp/trtmc-four-detr-test
/tmp/trtmc-four-detr-test
python -m tools.community_ci source-quality --base 714f1fc0d567213a7b79a488e9dcfdf405279c6a

Hardware, Environment, and Revisions

e853c2c: Ubuntu CPU, GCC 13.3; Transformers 5.2.0 reference.

Not Run / Remaining Gaps

Checkpoint inference and full CMake suite: TensorRT environment unavailable.

Contributor Self-Review

• I have completed a self-review of this change.

Notes For Future Readers

Half ties follow Python's round().

Risk level

• Low

Only DETR resize dimensions change.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: Path: .coderabbit.yaml

Review profile: CHILL

Plan: Enterprise

Run ID: 8ca0fb2c-c7b7-4945-bf31-81dd735b75b2

📥 Commits

Reviewing files that changed from the base of the PR and between 714f1fc and e853c2c.

📒 Files selected for processing (2)

• families/detr/runtime/image_preprocess_seam.cpp
• families/detr/tests/cpp/test_image_preprocess_seam.cpp

Included review availability: Your plan provides up to 12 included reviews per hour; 11 remain after this review.

---

📝 Summary

Summary

DETR preprocessing now matches reference resize behavior. hf_round uses ties-to-even rounding for exact half values. This changes a 600×1200 input resize from 667×1333 to 666×1333.

Tests cover half-tie and non-tie rounding for landscape and portrait inputs. They also verify engine-dimension compatibility.

Validation

• PASS: Native regression tests, 21 checks.
• PASS: Source-quality validation, 164 tests.
• BLOCK: Checkpoint inference and the full CMake suite were not run because TensorRT was unavailable.

Architecture impact

• Family-owned files remain within families/detr.
• No public or exported declarations changed.
• No shared implementation or new dependency direction was identified.
• DETR preprocessing consumers are affected by the corrected resize dimensions.
• HUMAN REVIEW REQUIRED: TensorRT-backed inference and full CMake validation remain unresolved.

Walkthrough

The DETR resize helper now matches Python’s ties-to-even rounding. Tests cover half-tie and non-tie dimensions for landscape and portrait inputs, plus preprocessing output dimensions.

Changes

DETR resize rounding

Layer / File(s)	Summary
Rounding implementation and resize validation families/detr/runtime/image_preprocess_seam.cpp, families/detr/tests/cpp/test_image_preprocess_seam.cpp	hf_round now rounds half-ties to the even integer. Tests cover tie and non-tie resize values, landscape and portrait inputs, preprocessing dimensions, and test registration.

Priority: ⬇️ Low

Estimated code review effort: 2 (Simple) | ~10 minutes

Change: Bug fix

Suggested reviewers: husizhtu

Merge Risk: ⚪ Minimal · up to e853c

The resize rounding update is covered by tie, non-tie, orientation, and preprocessing tests; no merge-blocking risk remains.

🚥 Pre-merge checks | ✅ 8 | ❌ 1

❌ Failed checks (1 warning)

Check name	Status	Explanation	Resolution
Docstring Coverage	⚠️ Warning	Docstring coverage is 12.50% which is insufficient. The required threshold is 80.00%. Docstring coverage is scoped to functions touched by this diff. Analyzed 8 functions across 2 files.	Write docstrings for the functions missing them to satisfy the coverage threshold.

✅ Passed checks (8 passed)

Check name	Status	Explanation
Title check	✅ Passed	The title clearly and concisely describes the main change: updating DETR resize rounding to match the reference behavior.
Description check	✅ Passed	The description covers the background, exit criteria, implementation, change category, validation results, environment, remaining gaps, self-review, and risk. It is sufficiently complete for the chang…
Linked Issues check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Out of Scope Changes check	✅ Passed	Check skipped because no linked issues were found for this pull request.
Family Ownership Boundary	✅ Passed	PASS. The authoritative diff changes only two files under families/detr. The runtime change at families/detr/runtime/image_preprocess_seam.cpp:40-44 uses the existing <cmath> dependency and does…
Shared Semantic Neutrality	✅ Passed	PASS. The pull request changes only families/detr/runtime/image_preprocess_seam.cpp and its C++ test. The semantic change is DETR-specific rounding in family-owned runtime preprocessing. The test ad…
Benchmark Validation Integrity	✅ Passed	PASS. The PR changes DETR resize rounding and adds validation for landscape, portrait, tie, and non-tie cases. The changed code does not add benchmark timing, synchronization, device-to-host transfer,…
Shared Change Blast Radius	✅ Passed	PASS: The pull request changes only DETR-family code and its DETR-local C++ tests. The modified hf_round is in an anonymous namespace, and the changed header/API is consumed by DETR pipeline.cpp, …

---

_{Comment @coderabbitai help to get the list of available commands.}

[yifeif-nv]

PR direction looks good. But community CI seems to be broken on this one. Let me retrigger