FAQ
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Data Labeling
How Does Image Annotation Work?
Image annotation is the process of marking objects, regions and features within an image so machine learning models can interpret and understand visual data. This work can be done by internal data science teams, but as machine learning (ML) projects require growing volumes of labeled data, it's commonly outsourced to specialized providers.
How Image Labeling Happens
Annotators are trained on the client's guidelines, then label images using the method suited to the task.
Methods include:
- Bounding boxes: Drawing a rectangle around an object to mark its location and boundaries
- Semantic segmentation: Labeling every pixel in an image according to the object or category it belongs to
- Keypoints: Marking specific points on an object, such as joints on a body or facial landmarks
- Object recognition: Identifying and labeling what an object is, without necessarily marking its exact boundaries
The real value of image annotation comes from handling complex cases, overlapping objects, ambiguous scenes and situations that require human judgment applied consistently against predefined guidelines.
Because consistency between annotators is critical, every project must include a QA layer: a second reviewer who audits the labeling work before it's delivered, catching errors and data drift before they reach your training data.
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