What is Stable Diffusion? A Beginner's Guide to the Open-Source AI Image Generator

Stable Diffusion has revolutionized the world of AI image generation. This tool has garnered particular attention among text-to-image AI technologies. Why is it so popular? What features make it special? This guide will explain everything in simple terms for beginners.

Since its release in August 2022, Stable Diffusion has been widely used by creators, developers, and general users worldwide¹. Its greatest feature is being “open source.” This means anyone can use it for free and modify it freely, setting it apart from other image generation AIs.

History and Development of Stable Diffusion

Origins

The birth of Stable Diffusion began with research at German universities. Researchers from Ludwig Maximilian University of Munich and Heidelberg University (Robin Rombach, Andreas Blattmann, Patrick Esser, and Dominik Lorenz) developed the foundational technology called “Latent Diffusion”².

Emad Mostaque, CEO of Stability AI, took notice of this technology. He co-founded Stability AI with Cyrus Hodes in November 2019 and provided computational resources for this research project. As a result, it was officially released as “Stable Diffusion” in August 2022¹.

Development Timeline

Period	Event	Significance
November 2019	Stability AI Founded	Co-founded by Emad Mostaque and Cyrus Hodes
August 2022	Stable Diffusion Released	Open-source and free release
November 2022	Version 2.0 Released	Added depth recognition “depth2img”³
February 2024	Version 3.0 Announced	Preview release, dramatic text generation improvements¹¹
June 2024	Version 3.0 Official Release	Multimodal Diffusion Transformer (MMDiT) architecture adopted¹¹
October 2024	Version 3.5 Released	More diverse image generation⁴

Why is Stable Diffusion So Popular?

1. Completely Free to Use

The biggest appeal is that it’s completely free. While other famous image generation AIs like Midjourney and DALL-E 3 require monthly fees, Stable Diffusion costs nothing if you run it on your own computer⁵.

2. Runs on Your Computer

With a computer equipped with an appropriate graphics card (GPU), it can operate without an internet connection. This protects your privacy and eliminates the need to send created images to external servers⁶.

3. Freedom to Customize

Being open source, anyone can improve the code or create versions specialized for specific purposes. In fact, models specialized in various styles such as anime, photorealistic, and watercolor have been developed and shared worldwide⁵.

Key Features and Functions

Basic Functions

Text-to-Image Generation (txt2img)
- Generate images from text descriptions
- Example: Input “a cat walking on a beach at sunset” and it creates that exact image
Image-to-Image Generation (img2img)
- Transform existing images into new ones
- Maintain style and composition while changing content
Inpainting
- Modify only parts of an image
- Remove or add unwanted elements
Outpainting
- Add new elements outside the image
- Expand narrow images

Technical Features

Stable Diffusion’s technical strength lies in its “Latent Space” mechanism. This makes it computationally lighter than other image generation AIs, enabling it to run on regular computers⁷.

Comparison with Other Image Generation AIs

Feature	Stable Diffusion	Midjourney	DALL-E 3
Price	Free (self-hosted)	$10+/month	$20/month (ChatGPT Plus)
Usage	Local/Online	Online only	Online only
Customization	High (open source)	Low	Low
Ease of Use	Intermediate	Beginner-friendly	Beginner-friendly
Image Quality	Realistic/Diverse	Artistic	Balanced
Text Generation	Improving (v3.5)	Poor	Good

About Emad Mostaque

Emad Mostaque, the former CEO of Stability AI, greatly contributed to the spread of Stable Diffusion. He advocated for “democratizing AI” and aimed to realize image generation technology accessible to everyone⁸.

However, he stepped down as CEO in March 2024. This was reportedly due to various challenges including difficulties in fundraising and the departure of key researchers⁹. Nevertheless, the open-source philosophy he left behind continues to be supported by many developers.

Current Status and Future

As of January 2025, Stable Diffusion remains a popular AI image generation tool. The significant updates in 2024 have greatly enhanced its performance.

Key Improvements in Version 3.0

Version 3.0, announced in February 2024, introduced groundbreaking improvements:

Complete text generation capability: Resolved the previous limitation of generating legible text, virtually eliminating spelling errors¹¹
New architecture: Transition from UNet to Multimodal Diffusion Transformer (MMDiT), integrating text and image processing¹¹
Improved multi-subject handling: Accurate generation of multiple subjects even with complex prompts¹¹
Enhanced photorealism: Significant improvements in rendering hands and faces¹¹
Better prompt understanding: Substantially narrowed the performance gap with DALL-E 3¹¹

Additional Enhancements in Version 3.5

The latest version 3.5 includes further improvements:

Enhanced diversity: Better generation of people with various ethnicities and features⁴
3D art support: More robust image generation across various styles including 3D art⁴
High resolution support: Capable of generating images up to 1 megapixel⁴

However, Stability AI itself faces business challenges, and the future development structure remains uncertain¹⁰. Nevertheless, due to its open-source nature, the technology is expected to continue evolving through the global developer community.

As AI-powered creative activities become more accessible, Stable Diffusion will continue to play an important role as a pioneer.