Azure Image Analysis Describe Image for Natural Language Captions
A library wants to automatically generate descriptive alt text for hundreds of historical photographs in their digital archive. For each photo, the system should produce a natural-language description that includes objects present (e.g., 'a horse', 'a carriage'), the action being performed (e.g., 'pulling'), and the scene type (e.g., 'city street'). Which Azure Computer Vision capability should they use?
Quick Answer
The answer is the Image Analysis 'Describe image' capability. This Azure Computer Vision feature is specifically designed to generate natural language captions that describe an image's content, including objects like a horse or carriage, actions such as pulling, and the overall scene type like a city street. It works by combining object detection with scene understanding to output a full, human-readable sentence, which directly meets the library’s need for automated alt text. On the AI-900 exam, this question tests your ability to match a business requirement to the correct Azure service, often contrasting 'Describe image' with Optical Character Recognition (OCR) or object detection alone. A common trap is confusing it with the 'Tag' feature, which only lists keywords without forming a sentence. For a quick memory tip, think of the word 'caption' as a complete sentence, while 'tag' is just a label—if you need a full description, always choose 'Describe image'.
⚠ Common exam trap
Microsoft often tests the distinction between 'Describe image' (which outputs a full sentence) and 'Object detection' (which only outputs labels and bounding boxes), causing candidates to confuse a component feature with the end-to-end captioning capability.
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
✓
Image Analysis (Describe image)
The Image Analysis 'Describe image' capability is designed to generate human-readable captions that summarize the content of an image, including objects, actions, and scene context. This directly matches the library's requirement to produce natural-language descriptions for historical photographs, as it uses a combination of object detection and scene understanding to output a full sentence.
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 this is correct
The describe feature of Image Analysis creates natural-language captions summarizing the content of an image, including objects and actions.
- ✗
Optical Character Recognition (OCR)
Why it's wrong here
OCR extracts printed or handwritten text from images, not descriptions of visual content.
- ✗
Object detection
Why it's wrong here
Object detection finds and labels objects with bounding boxes, but does not generate a natural-language description or provide action context.
- ✗
Face detection
Why it's wrong here
Face detection identifies human faces in images, not general objects, actions, or scenes.
Go deeper
Related to this question
Learn chapter
Azure Machine Learning Studio
Key term
Object detection
Object detection is a computer vision technology that identifies and locates specific objects within an image or video.
Key term
Computer vision
Computer vision is a field of artificial intelligence that enables computers to interpret and make decisions based on visual data from the world, such as images and videos.
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Same concept, more angles
1 more way this is tested on AI-900
These questions test the same concept from different angles. Work through them to make sure you can recognise it however the exam phrases it.
Variation 1. A social media platform wants to automatically generate a textual description for each user-uploaded image to assist visually impaired users. Which prebuilt Azure Computer Vision feature should they use?
easy- A.Object detection
- ✓ B.Image captioning
- C.Optical Character Recognition (OCR)
- D.Face detection
Why B: Azure AI Vision's Image Analysis API provides an image captioning feature that generates a human-readable sentence describing the entire image. Object detection returns object labels and bounding boxes, OCR extracts text, and face detection identifies faces, none of which produce a full textual description.
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.