Fix/ImgDetectionFilter segmentation mask reindexing

[tadeas0]

Purpose

Reindex segmentation masks in ImgDetectionsFilter to match the new filtered detection list indices.

Specification

None / not applicable

Dependencies & Potential Impact

None / not applicable

Deployment Plan

None / not applicable

Testing & Validation

Added unit tests for this modified behavior. Validated all oak-examples with ImgDetectionsFilter still work as before.

AI Usage

Assisted-by: Pi Coding Agent:GPT-5.5

Submitted code was reviewed by a human: YES

The author is taking the responsibility for the contribution: YES

Summary by CodeRabbit

• Bug Fixes

  • Improved segmentation-mask updates after filtering, sorting, non-maximum suppression, and limiting detections.
  • Preserved correct instance and class labels for retained detections.
  • Handled invalid mask labels and cases with no remaining detections by treating affected areas as background.

• Tests

  • Added coverage for mask behavior across detection filtering and truncation scenarios.

[coderabbitai]

No actionable comments were generated in the recent review. 🎉

ℹ️ Recent review info

⚙️ Run configuration

Configuration used: defaults

Review profile: CHILL

Plan: Pro

Run ID: b8b9c951-e449-4940-9677-23773eb0d98d

📥 Commits

Reviewing files that changed from the base of the PR and between 60c8202 and 4581d25.

📒 Files selected for processing (2)

• depthai_nodes/node/img_detections_filter.py
• tests/unittests/test_nodes/test_host_nodes/test_img_detections_filter_node.py

---

📝 Walkthrough

Walkthrough

ImgDetectionsFilter now preserves original detection indices through filtering, NMS, sorting, and truncation, then uses those indices to remap segmentation masks. Unit tests cover reordered, suppressed, truncated, invalid, and empty detection results.

Changes

Detection filtering and mask handling

Layer / File(s)	Summary
Indexed detection processing depthai_nodes/node/img_detections_filter.py	Filtering, NMS, sorting, and first_k selection now operate on indexed detection tuples before rebuilding the output detection list.
Segmentation-mask remapping and validation depthai_nodes/node/img_detections_filter.py, tests/unittests/test_nodes/test_host_nodes/test_img_detections_filter_node.py	Segmentation masks are remapped using kept original indices, with tests covering sorting, NMS, truncation, invalid labels, and empty outputs.

Estimated code review effort: 3 (Moderate) | ~20 minutes

Suggested reviewers: klemen1999, tersekmatija

🚥 Pre-merge checks | ✅ 5

✅ Passed checks (5 passed)

Check name	Status	Explanation
Description Check	✅ Passed	Check skipped - CodeRabbit’s high-level summary is enabled.
Title check	✅ Passed	The title clearly reflects the main change: reindexing segmentation masks in ImgDetectionsFilter.
Docstring Coverage	✅ Passed	No functions found in the changed files to evaluate docstring coverage. Skipping docstring coverage check.
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.

✨ Finishing Touches

📝 Generate docstrings

• Create stacked PR
• Commit on current branch

🧪 Generate unit tests (beta)

• Create PR with unit tests
• Commit unit tests in branch fix/img_detection_filter_seg_mask_reindexing

---

Thanks for using CodeRabbit! It's free for OSS, and your support helps us grow. If you like it, consider giving us a shout-out.

❤️ Share

• X
• Mastodon
• Reddit
• LinkedIn

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

[codecov-commenter]

Codecov Report

✅ All modified and coverable lines are covered by tests.
✅ Project coverage is 48.21%. Comparing base (60c8202) to head (4581d25).
⚠️ Report is 1 commits behind head on main.
✅ All tests successful. No failed tests found.

Additional details and impacted files

@@            Coverage Diff             @@
##             main     #306      +/-   ##
==========================================
+ Coverage   48.18%   48.21%   +0.03%     
==========================================
  Files          99       99              
  Lines        6438     6442       +4     
==========================================
+ Hits         3102     3106       +4     
  Misses       3336     3336              

☔ View full report in Codecov by Harness.
📢 Have feedback on the report? Share it here.

[klemen1999]

LGTM