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Object Detection

Explore object detection fundamentals including bounding boxes and confidence scores. Understand classical methods, CNN detectors like Faster R-CNN and YOLO, and transformer-based models such as DETR, DINO, and Grounding-DINO. Gain hands-on experience using Hugging Face pipelines to run object detection on images efficiently.

Object detection is a core computer vision task that enables machines to identify what objects appear in an image and where they are located. Unlike image classification, which assigns a single label to an entire image, object detection produces a set of detected objects, each with a bounding box and a confidence score.

This capability is foundational to many real-world applications, including:

  • Autonomous driving and traffic monitoring

  • Retail shelf analytics

  • Medical imaging and diagnostics

  • Industrial inspection and robotics

An example of object detection
An example of object detection

From classical computer vision to deep learning

Before deep learning, object detection relied on manually crafted features.

Techniques such as Haar Cascades and Histogram of Oriented Gradients (HOG) searched for edges, textures, and patterns defined by humans. While these methods were fast, they were fragile—their performance dropped sharply when objects appeared under different lighting conditions, angles, or backgrounds. CNN-based detectors transformed this approach. Convolutional layers automatically learn relevant features directly from data, shifting image understanding from manual feature engineering to end-to-end learning.

Two-stage vs. one-stage object detectors

Academic research and industry quickly converged on two families of architectures:

  • Two-stage models (R-CNN → Fast R-CNN → Faster R-CNN):

    • They first generate region proposals, then classify them. This two-step process makes them highly accurate and reliable for medical imaging, satellite data, and scientific analysis, where missing an object can be costly.

  • One-stage models (SSD, YOLO):

    • They skip proposals and predict boxes + labels in one pass. This makes them fast and real-time, ideal for drones, robotics, traffic cameras, and mobile apps. ...