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AI-900 Practice Question: Describe features of computer vision workloads on Azure

A security company wants to monitor a restricted area using camera feeds. The system must detect if a person is present in each video frame and draw a rectangle around each detected person. Which Azure Cognitive Services Computer Vision capability should they use?

⚠ Common exam trap

Test-takers frequently confuse Face Detection (which only finds faces) with Object Detection (which finds full persons and other objects), leading them to choose D when the requirement is to detect entire people, not just their faces.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

Object Detection

Object Detection is the correct capability because it identifies and locates objects (including people) within an image by drawing bounding boxes around each detected instance. This directly matches the requirement to detect persons in video frames and draw rectangles around them, which is a core function of the Object Detection API in Azure Cognitive Services Computer Vision.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

  • Image Analysis (Describe image)

    Why it's wrong here

    Image Analysis (Describe image) produces a natural-language sentence or tag list summarizing the scene, such as 'a person standing in a warehouse,' but it does not output per-object bounding boxes or coordinates. A security system needs the position and size of each person to determine if they are inside a restricted zone, while a description is insufficient for spatial monitoring and alerting.

    When this WOULD be correct

    A question asking for generating a caption or description of an image, such as 'Which capability can provide a text description of the main subjects and actions in an image?'

  • Object Detection

    Why this is correct

    Object Detection identifies people by localizing each instance with a bounding box and class label, and it returns confidence scores so the system can alert when any person enters the restricted area. That fits the monitoring use case because it supports multiple object classes, can track or count people across frames, and produces coordinates that can trigger alarms.

  • Optical Character Recognition (OCR)

    Why it's wrong here

    OCR is designed to extract printed or handwritten characters from an image and returns recognized text along with text bounding boxes, but it has no object-class model for people or other physical objects. It could read signs or license plates in the area, but it cannot indicate whether a person is present, so it is fundamentally incompatible with this monitoring task.

    When this WOULD be correct

    A question asks: 'Which Azure Cognitive Services capability should be used to extract printed or handwritten text from images of documents or signs?' OCR would be the correct answer for text extraction scenarios.

  • Face Detection

    Why it's wrong here

    Face Detection identifies human faces and returns facial attributes such as landmarks, emotions, or age, but it does not perform general person detection or draw bounding boxes around entire bodies. The requirement is to detect any person present in a frame, not specifically a face; a person turned away from the camera would be missed. This option tempts because Face Detection is a well-known Computer Vision feature for locating people in images, and it would be correct if the task were to detect and frame only visible faces for identity verification or emotion analysis.

    When this WOULD be correct

    A question like 'Which Computer Vision capability should be used to detect and locate human faces in an image for a facial recognition system?' would make Face Detection correct.

Option-by-option analysis

Why each answer is right or wrong

Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The AI-900 exam frequently reuses these exact scenarios with slightly different constraints.

Object DetectionCorrect answer

Why this is correct

Object Detection identifies people by localizing each instance with a bounding box and class label, and it returns confidence scores so the system can alert when any person enters the restricted area. That fits the monitoring use case because it supports multiple object classes, can track or count people across frames, and produces coordinates that can trigger alarms.

Image Analysis (Describe image)Wrong answer — click to see why

Why this is wrong here

Image Analysis (Describe image) generates a human-readable description of the image content, but does not provide bounding box coordinates for detected objects, which is required to draw rectangles around each person.

★ When this WOULD be the correct answer

A question asking for generating a caption or description of an image, such as 'Which capability can provide a text description of the main subjects and actions in an image?'

Why candidates choose this

Candidates may confuse the general 'describe image' feature with object detection, assuming it can locate objects, but it only provides a textual summary without spatial localization.

Optical Character Recognition (OCR)Wrong answer — click to see why

Why this is wrong here

Optical Character Recognition (OCR) extracts text from images, not people. The question requires detecting persons and drawing bounding boxes around them, which is object detection, not text recognition.

★ When this WOULD be the correct answer

A question asks: 'Which Azure Cognitive Services capability should be used to extract printed or handwritten text from images of documents or signs?' OCR would be the correct answer for text extraction scenarios.

Why candidates choose this

Candidates may confuse OCR with general image analysis or think 'recognition' includes people, but OCR specifically refers to text recognition, not object or person detection.

Face DetectionWrong answer — click to see why

Why this is wrong here

Face Detection identifies and locates human faces, but does not draw bounding boxes around entire persons or detect people without visible faces. The question requires detecting any person present, not just faces.

★ When this WOULD be the correct answer

A question like 'Which Computer Vision capability should be used to detect and locate human faces in an image for a facial recognition system?' would make Face Detection correct.

Why candidates choose this

Candidates may confuse detecting a person with detecting a face, assuming that face detection is sufficient for person detection, or they may not distinguish between the two capabilities.

Analysis generated from the official AI-900blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”

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JA

Written by Johnson Ajibi, MSc IT Security

Senior Network & Security Engineer · founder of Courseiva

This AI-900 practice question is part of Courseiva's free Microsoft certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the AI-900 exam.