2026.02.19

Stable Diffusion Complete Guide [2025] – How to Start, Use & Commercial Licensing with SD3.5

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Stable Diffusion is an open-source image generation AI developed by Stability AI. Simply by providing text instructions, it can automatically generate illustrations, photo-realistic images, and artwork. Since its launch in 2022, it has become synonymous with AI image generation.

Its biggest advantage is that it runs completely free on your local PC. Unlike cloud services such as Midjourney or DALL-E, you can generate as many images as you want without any monthly subscription fees.

This article comprehensively covers everything from the overall picture of Stable Diffusion as of 2026, to installation methods, prompt tips, and recommended models. The goal is for beginners to start from zero and actually be able to generate images.

忍者AdMax

Latest Versions and How to Choose

As of February 2026, multiple versions of Stable Diffusion exist. Let’s organize the features of each.

SD3.5 Series (Latest)

The latest model with 8 billion parameters. It comes in three variants: Large (high quality), Turbo (high speed), and Medium (lightweight). Text rendering accuracy has been dramatically improved, and hand/finger depiction has also gotten better. However, the variety of custom models and LoRAs is still limited.

SDXL (De Facto Standard)

Released in 2023. It supports high resolution (1024×1024), and a massive number of custom models and LoRAs are available on Civitai and Hugging Face. We strongly recommend beginners start with SDXL. The community is the most active, and troubleshooting information is abundant.

SD1.5 (Legacy but Still Popular)

The version with the longest history. It can run with as little as 4GB of VRAM, making it usable on older PCs. Anime-style custom models are particularly well-developed, and it remains a strong choice when you want to pursue a specific style.

Required PC Specifications

Running Stable Diffusion locally requires a decent graphics card (GPU). Here are the recommended specs:

GPU: NVIDIA RTX 3060 (12GB VRAM) or higher recommended. RTX 4060 or RTX 4070 will run comfortably
RAM: 16GB or more (32GB recommended)
Storage: SSD recommended. Each model is 2-7GB, so at least 100GB of free space is desirable
OS: Windows 10/11 or Linux. macOS (Apple Silicon) also works but is slower

If you don’t have a GPU, you can use cloud services like Google Colab or Paperspace. However, free tiers have limitations, so if you want to use it seriously, prepare a PC with a dedicated GPU.

Installation: Choosing Between Two UIs

To use Stable Diffusion, you need to install a UI tool (interface). The two main options currently available are:

Stable Diffusion WebUI Forge (For Beginners)

A browser-based UI that’s intuitive to operate. It’s an improved version of the original WebUI (AUTOMATIC1111), with reduced VRAM usage and faster generation speed. Beginners should start here.

Installation steps:

Install Python (3.10 recommended)
Install Git
Run git clone https://github.com/lllyasviel/stable-diffusion-webui-forge in Command Prompt
Run webui.bat (necessary files will be automatically downloaded on first run)
Open http://127.0.0.1:7860 in your browser

ComfyUI (For Intermediate to Advanced Users)

A node-based UI where you can visually build processing workflows. It offers extremely high flexibility and allows full utilization of advanced features like ControlNet and IPAdapter. However, the learning curve is steep, so we recommend transitioning to it after getting comfortable with WebUI Forge.

Prompt Basics and Writing Tips

In Stable Diffusion, you instruct the AI what image to generate using text. This instruction text is called a “prompt” (commonly known as a “spell” in Japan). The way you write your prompt dramatically affects the quality of generated images.

Basic Structure

The basic approach is to write prompts in English, listing elements separated by commas:

1girl, long hair, blue eyes, school uniform, cherry blossom, spring, sunshine, high quality, masterpiece

Generally, arranging elements in the following order tends to produce better results:

Quality tags: masterpiece, best quality, high resolution
Subject: 1girl, 1boy, landscape, building
Subject details: hair color, eye color, clothing
Background/environment: outdoor, night, forest, city
Style/atmosphere: cinematic, anime style, photorealistic

Negative Prompts

Negative prompts specify “things you don’t want drawn.” Setting these appropriately alone can dramatically improve image quality:

low quality, worst quality, blurry, deformed, extra fingers, bad anatomy, watermark, text

“Extra fingers” and “bad anatomy” are practically essential for character illustrations. AI still struggles with hand and finger depiction, so specifying these alone makes a significant improvement.

Top 5 Recommended Custom Models

The true power of Stable Diffusion lies in the massive library of custom models published by the community. Here are the most popular models as of 2026, all downloadable from Civitai (civitai.com):

Animagine XL 4.0: The go-to model for high-quality anime illustrations. SDXL-based
RealVisXL: Specialized in photorealistic images. Excels at portrait-style photography
Pony Diffusion V7: Strong across all illustration styles. Responds well to detailed tag specifications
DreamShaper XL: Designed for fantasy and concept art. Beautiful background rendering
Juggernaut XL: All-purpose model. Handles everything from photo-realistic to illustration styles

Installing models is simple — just place the downloaded .safetensors file in the designated folder (models/Stable-diffusion/).

Common Troubleshooting

“CUDA out of memory” error: VRAM shortage. Reduce image size or add the –medvram option and restart
Black images are generated: Often caused by a mismatch between the model and VAE. Change to the appropriate VAE
Hands and fingers are distorted: Add “bad hands, extra fingers” to negative prompts. Installing the ADetailer plugin is also effective
Generation is slow: Consider enabling xformers, reducing generation size, or using Turbo models

Stable Diffusion vs Other Image Generation AIs

Here’s a comparison with other image generation AI services:

Midjourney: Highest quality but costs $10+/month. Requires Discord for operation. Commercial use allowed
DALL-E 3 (ChatGPT): Supports Japanese prompts. Easy to use but limited flexibility
Adobe Firefly: Trained on copyright-cleared data. Safest for commercial use
Stable Diffusion: Free, unlimited, fully customizable. However, requires PC knowledge to set up

Bottom line: if you want “free with maximum customization” and “everything running on your own PC,” Stable Diffusion is the only choice. The setup hurdle is higher than others, but once you’ve configured your environment, you gain a level of freedom and possibility that no other service can match.

Commercial Use and Copyright

Many people wonder about commercial use of images generated with Stable Diffusion. Stability AI has released Stable Diffusion under an open-source license, and commercial use of generated images is generally permitted. However, there are several important considerations:

Images too similar to existing works are not acceptable: Images generated by specifying a particular artist’s name in the prompt carry a risk of copyright infringement. For commercial use, use prompts with high originality
Check custom model licenses: Custom models distributed on Civitai and similar platforms each have their own licenses. Some models prohibit commercial use, so always verify the license
Use caution with portraits: If you accidentally generate an image resembling a real person, issues with portrait rights and publicity rights may arise. Exercise particular caution for commercial use
Japanese legal landscape: Japan’s Agency for Cultural Affairs summarized its position on “AI and Copyright” in March 2024, organizing the copyright status of AI-generated works. It suggests that copyright may be recognized when AI is used as a tool and humans make creative contributions

Practical Application Ideas

Blog and Social Media Thumbnails

Stable Diffusion is extremely useful for creating thumbnail images for blog posts and social media. Without using paid stock photo services, you can create original images perfectly matched to your content for free. Using ControlNet, you can specify compositions while generating images, achieving results closer to your vision.

Doujinshi and Merchandise Creation

More and more people are using it for original character design and background illustration generation. Using img2img mode, you can transform rough sketches into high-quality illustrations. However, when using LoRA models, be mindful of each model’s license terms.

Game Development Prototyping

For indie game developers, it’s invaluable as a tool for generating concept art and texture assets. Whether or not you use them as final assets, the ability to quickly establish visual direction during early development stages is a major advantage.

Latest Trends and Future Outlook

The landscape around Stable Diffusion is changing rapidly. Since 2024, Stability AI has released the SD3 series, dramatically improving text rendering accuracy and image quality. ComfyUI’s popularity has also surged, enabling visual construction of complex image generation pipelines through node-based workflows.

Meanwhile, copyright lawsuits regarding AI training data are ongoing worldwide, and future legislation may change usage conditions. It remains important to stay updated on the latest information while using the technology appropriately and safely.

Frequently Asked Questions (FAQ)

Is Stable Diffusion completely free?

Yes, the Stable Diffusion software itself is free. However, generating high-quality images requires a high-performance GPU (8GB+ VRAM recommended), so your PC needs adequate specs. If using cloud services, GPU usage fees will apply.

Can I use Stable Diffusion on a Mac?

Yes, Stable Diffusion can run on Macs with Apple Silicon chips. AUTOMATIC1111 and ComfyUI have progressed in Mac compatibility and work on M1/M2/M3 chips. However, generation speed will be somewhat slower compared to a similarly-priced NVIDIA GPU-equipped PC.

How can I improve the quality of generated images?

First, properly set negative prompts to exclude low-quality elements. Next, use the Hires.fix feature to upscale, which dramatically improves detail. Additionally, the ADetailer extension can automatically improve facial and hand rendering accuracy.

For those concerned about GPU performance or who want to try it out easily first, using Google Colab is also recommended. This cloud environment provided by Google allows some image generation even with the free tier. You can get started with just a web browser, so you can experience Stable Diffusion without worrying about PC specs. Subscribing to the paid Colab Pro plan gives access to more powerful GPUs for longer periods.

Conclusion: Enjoy the World of Image Generation with Stable Diffusion

Stable Diffusion’s greatest appeal is its high degree of freedom as open-source software. By combining the latest models like SD3.5 and SDXL, diverse UIs like AUTOMATIC1111 and ComfyUI, and the abundance of custom models and LoRAs, you can generate unlimited original images uniquely your own.

Start by installing WebUI and casually experimenting with simple prompts. Even if your initial results don’t match your expectations, you’ll feel the quality steadily improving as you refine your prompts and adjust parameters.

The world of AI image generation is incredibly deep, and once you start exploring, the fun never stops. Keep commercial use in mind while first savoring the joy of creating your own original works.

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