Practical articles on region-of-interest annotation, annotation formats, computer vision zone workflows, and image labelling tools.
Learn how to define polygon detection zones in OpenCV using Python — draw them with RegionKit, export the coordinates as JSON, and use cv2.fillPoly and cv2.pointPolygonTest to filter detections to your zones.
Read articleBounding boxes are faster to draw; polygons are more precise. Knowing when each is appropriate — and when the difference actually matters — saves time and improves your CV system's performance.
Read articleStep-by-step guide to annotating floor plans with detection zones, room boundaries, and camera coverage areas using a browser-based tool. No install required — export coordinates for your CV pipeline.
Read articleLearn how to plan camera coverage zones for security and CV systems — drawing field-of-view polygons, overlapping detection areas, and exclusion zones for privacy compliance. With a free, browser-based zone editor.
Read articleA complete reference for the YOLO annotation format — how normalised coordinates work, the class ID system, directory structure, data.yaml, and how to convert to and from COCO. With working Python examples.
Read articleStep-by-step guide to creating valid COCO JSON annotation files — using RegionKit to draw annotations and export them, with Python examples for loading and validating the output.
Read articleA tripwire (or virtual tripwire) is a line drawn across a camera's field of view that triggers an event when an object crosses it. Learn how they work, when to use them, and how to define them with a browser-based tool.
Read articleAn honest comparison of the best free annotation tools in 2025 — CVAT, Label Studio, Roboflow, makesense.ai, and RegionKit. Which tool fits your workflow depends entirely on what you're trying to annotate and why.
Read articleImplement object counting across a virtual tripwire in OpenCV Python — using a tracker, a crossing detection function, and zone coordinates exported from RegionKit. Includes direction-aware counting.
Read articleExclusion zones filter out regions your CV system should ignore — reducing false positives, protecting privacy, and improving detection accuracy. Learn why they matter and how to define them precisely.
Read articleCompare approaches to sharing image annotations with teammates — email attachments, shared drives, JSON exports, and shareable URLs. RegionKit's publish flow makes review and collaboration instant.
Read articleBrowser-based annotation tools have closed the gap on desktop tools. Here's where each genuinely wins — and where the conventional wisdom about desktop performance advantages no longer holds.
Read articleLearn how to define regions of interest (ROIs) for computer vision systems — detection zones, exclusion areas, tripwires, and coverage boundaries — and export precise polygon coordinates to your pipeline.
Read articleA clear explanation of the COCO JSON annotation format — its structure, when to use it, and how to generate valid COCO exports using RegionKit without writing a single line of code.
Read articleStep-by-step guide to annotating images for YOLO object detection training using RegionKit — a free, browser-based tool. Draw bounding boxes, export YOLO TXT, and plug coordinates directly into your training pipeline.
Read articleAn honest comparison of the best free image annotation tools available in 2025 — covering CVAT, Label Studio, Roboflow, and RegionKit. Which tool fits your workflow depends on what you're actually trying to do.
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