What is 'object detection' in computer vision and how does it differ from image classification?
Object detection outputs a set of bounding-box coordinates around each recognized object along with a class label and often a confidence score for every instance in the image. Image classification, by contrast, produces a single label or probability distribution over class labels for the entire image without any spatial localization. Detection gives both location and identity, enabling tasks like counting or tracking objects, while classification simply categorizes the image's overall content.
Why this answer
Object detection goes beyond image classification by not only identifying the class of objects present but also localizing each one with a bounding box. In contrast, image classification assigns a single label to the entire image, regardless of how many objects are present. This distinction is fundamental in computer vision workloads on Azure, where Custom Vision and Computer Vision API offer both capabilities.
Exam trap
The trap here is that candidates may confuse object detection with image classification because both involve labeling objects, but the key differentiator is localization—object detection provides spatial coordinates (bounding boxes), while classification does not.
How to eliminate wrong answers
Option A is wrong because object detection and image classification do not produce the same output; classification labels the entire image, while detection outputs bounding boxes and labels for each object. Option C is wrong because while image classification is generally simpler and can be faster, the statement is not a defining difference—object detection is not inherently slower in all implementations, and the question asks for the functional difference, not performance. Option D is wrong because object detection is specifically designed to handle multiple objects in a single image, not just a single object; classification can also handle multiple objects but only produces one label for the whole scene.