Génération d'images par IA : guide complet pour débutants [2026]

AI image generation lets you create high-quality images automatically just by typing text instructions (prompts). You no longer need design expertise to create professional-level visuals. This article covers everything from the basics to hands-on techniques for AI image generation.

What Is AI Image Generation?

AI image generation is a technology where you type a text instruction (prompt) and AI creates an image based on that description. The underlying technology, known as "diffusion models," generates high-quality images through a process that gradually reconstructs images from noise.

Major AI Image Generation Tools

Midjourney

Midjourney is one of the most popular AI image generation tools. You enter prompts through Discord or the official web app. It is especially renowned for artistic, beautiful image generation and is highly valued by designers and creators.

Pricing: Basic $10/month, Standard $30/month, Pro $60/month Strengths: Artistic expression, high image quality, style diversity Getting started: Create an account at midjourney.com and start entering prompts

DALL-E (OpenAI)

Developed by OpenAI, DALL-E is integrated into ChatGPT, allowing you to generate images within a conversation. It has excellent natural language understanding and responds accurately to detailed instructions. Available with ChatGPT Plus and above.

Pricing: Included with ChatGPT Plus ($20/month) Strengths: ChatGPT integration, natural language understanding, image editing capabilities Getting started: Simply type "generate an image of..." in ChatGPT

Stable Diffusion

Stable Diffusion is an open-source AI image generation model that can run locally on your computer. It offers the highest customization potential, allowing you to use custom models and LoRA (fine-tuned weights) to reproduce specific styles. It requires more technical knowledge, but the freedom it provides is unmatched.

Pricing: Free (local execution) / Paid for cloud services Strengths: Open-source, highly customizable, local execution Getting started: Set up an interface like ComfyUI or WebUI (AUTOMATIC1111)

How to Write Effective Prompts

The most important factor in AI image generation quality is the prompt. Here is how to write effective ones:

Basic Structure

An effective prompt typically includes:

1. Main subject: What to depict (e.g., "golden retriever," "Tokyo skyline at night") 2. Style: The visual aesthetic (e.g., "watercolor painting," "photorealistic," "anime style") 3. Composition: Camera angle (e.g., "close-up," "bird's eye view," "front-facing") 4. Lighting: Type of light (e.g., "soft golden hour light," "studio lighting") 5. Quality modifiers: Image quality (e.g., "high resolution," "4K," "highly detailed")

Prompt Examples

Simple example: "A woman reading a book under a cherry blossom tree, watercolor style, soft lighting"

Detailed example: "New York City skyline at dusk, rain-soaked streets reflecting neon lights, cinematic atmosphere, high resolution, 16:9 aspect ratio"

What to Avoid

• Vague instructions ("a cool picture")
• Contradictory instructions ("dark room with bright sunlight")
• Overly long prompts (cramming too many elements reduces quality)

Use Cases

Business

• Blog featured images
• Presentation visuals
• Social media graphics
• Ad banner design concepts

Creative

• Art creation
• Concept art
• Character design
• Background illustrations

Personal

• Profile pictures and avatars
• Custom wallpapers
• Original merchandise designs

Copyright and Legal Considerations

When using AI image generation, keep these points in mind:

1. Copyright: The legal treatment of AI-generated images varies by country and jurisdiction. Always check the terms of service for any tool you use commercially. 2. Commercial use: Commercial use policies differ by tool. Midjourney allows commercial use on paid plans, but always verify the specific terms. 3. Ethical considerations: Avoid generating images that closely resemble real people or could be misleading. 4. Quality checks: AI-generated images may contain artifacts (such as unnatural hands). Always review and touch up images before commercial use.

Summary

AI image generation is a revolutionary technology that democratizes creative work. By refining your prompts, anyone can create surprisingly high-quality images. Start with DALL-E (via ChatGPT) to experience AI image generation for free, and once you master the art of prompting, the creative possibilities are virtually limitless.