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— CH. 1 · ORIGINS AND DEVELOPMENT HISTORY —

Stable Diffusion

~3 min read · Ch. 1 of 6
6 sections
  • In 2021, researchers at Ludwig Maximilian University of Munich and Heidelberg University began work on a project called Latent Diffusion. Four of the original five authors later joined Stability AI to release subsequent versions of Stable Diffusion. Patrick Esser of Runway led development alongside Robin Rombach from CompVis. The team received computational donations from Stability AI and training data support from LAION, a German nonprofit organization. The model was released publicly in August 2022 with version numbers starting from 1.1 rather than 1.0. This marked a significant departure from previous proprietary text-to-image models like DALL-E and Midjourney which remained accessible only through cloud services.

  • The system consists of three core components: a variational autoencoder, a U-Net block, and an optional text encoder. Gaussian noise gets iteratively applied to compressed latent representations during forward diffusion processes. The U-Net block uses a ResNet backbone to denoise outputs backwards into usable latent representations. Finally, the VAE decoder converts these representations back into pixel space for final images. With 860 million parameters in the U-Net and 123 million in the text encoder, the model runs on consumer GPUs with as little as 2.4 GB VRAM. Researchers point to increased computational efficiency as a key advantage over earlier diffusion models developed before 2021.

  • Version 1.5 arrived in October 2022 with 983 million parameters initialized from weights of version 1.2. Stability AI released SD XL 1.0 in July 2023 containing 3.5 billion parameters making it approximately 3.5 times larger than previous iterations. The company introduced SD 3.0 in February 2024 featuring 800 million to 8 billion parameters across different model families. By October 2024, SD 3.5 Large reached between 2.5 billion and 8 billion parameters. Version 2.0 launched in November 2022 after being retrained from scratch on filtered datasets. Each iteration addressed specific limitations while expanding parameter counts significantly beyond initial releases.

  • Stable Diffusion trained on pairs of images and captions taken from LAION-5B, a dataset derived from Common Crawl data scraped from the web. Approximately 47% of sample images came from just 100 different domains including Pinterest which accounted for 8.5% of subsets. An investigation by Bayerischer Rundfunk revealed large amounts of private and sensitive data within LAION's datasets hosted on Hugging Face. The creators acknowledge that generated images reinforce social biases due primarily to training on English descriptions. Western or white cultures often become default representations because the model lacks sufficient data from other communities and cultures. Generated results prove more accurate for prompts written in English compared to those using other languages.

  • Stability AI released source code and pretrained weights publicly unlike models like DALL-E which remained proprietary. The Creative ML OpenRAIL-M license prohibits certain use cases including crime, libel, harassment, doxing, exploiting minors, giving medical advice, producing legal evidence, and discriminating against individuals based on social behavior or personal characteristics. Users own rights to generated output images and may use them commercially provided content remains legal. CEO Emad Mostaque argued that putting capabilities into public hands would result in net benefits despite potential negative consequences. A hack targeting ComfyUI extensions occurred in June 2024 with hackers claiming they targeted users who committed sins including art theft and promoting cryptocurrency. Controversy around photorealistic sexualized depictions of underage characters emerged due to such images being shared on websites like Pixiv.

Common questions

When was Stable Diffusion first released to the public?

Stable Diffusion was released publicly in August 2022 with version numbers starting from 1.1 rather than 1.0.

Who developed the original Latent Diffusion project at Ludwig Maximilian University of Munich and Heidelberg University?

Researchers Patrick Esser of Runway and Robin Rombach from CompVis led development alongside four other authors who later joined Stability AI.

What are the core components that make up the Stable Diffusion system architecture?

The system consists of a variational autoencoder, a U-Net block, and an optional text encoder which work together to generate images from noise.

Why did three artists file a copyright infringement lawsuit against Stability AI in January 2023?

Sarah Andersen, Kelly McKernan, and Karla Ortiz claimed companies infringed rights of millions of artists by training tools on five billion images scraped without consent.

How many parameters does the SD XL 1.0 model contain compared to previous iterations?

Stability AI released SD XL 1.0 in July 2023 containing 3.5 billion parameters making it approximately 3.5 times larger than previous iterations.

All sources

98 references cited across the entry

  1. 2webHow to Run Stable Diffusion Locally to Generate ImagesRyan O'Connor — August 23, 2022
  2. 7webStable Diffusion Repository on GitHubCompVis - Machine Vision and Learning Research Group, LMU Munich — 17 September 2022
  3. 8webbasujindal/stable-diffusion16 November 2022
  4. 11bookGenerative Deep LearningFoster David — O'Reilly
  5. 12arxivDeep Unsupervised Learning using Nonequilibrium ThermodynamicsJascha Sohl-Dickstein, Eric A. Weiss, Niru Maheswaranathan, Surya Ganguli — 12 March 2015
  6. 13webHome
  7. 17citationScaling Rectified Flow Transformers for High-Resolution Image SynthesisPatrick Esser et al. — 2024-03-05
  8. 18citationFlow Straight and Fast: Learning to Generate and Transfer Data with Rectified FlowXingchao Liu et al. — 2022-09-07
  9. 22webWe Are All Raw Material for AIKatharina Brunner et al. — Bayerischer Rundfunk (BR) — 2023-07-07
  10. 23citationCLIP+MLP Aesthetic Score PredictorChristoph Schuhmann — 2022-11-02
  11. 25arxivClassifier-Free Diffusion GuidanceJonathan Ho et al. — 2022-07-25
  12. 26webCost of constructionEmad Mostaque — August 28, 2022
  13. 30webLAION
  14. 35arxivAdapting Pretrained Vision-Language Foundational Models to Medical Imaging DomainsPierre Chambon et al. — 2022-10-09
  15. 37citationWaifu DiffusionAnthony Mercurio — 2022-10-31
  16. 41arxivAn Image is Worth One Word: Personalizing Text-to-Image Generation using Textual InversionRinon Gal et al. — 2022-08-02
  17. 44arxivSDEdit: Guided Image Synthesis and Editing with Stochastic Differential EquationsChenlin Meng et al. — August 2, 2021
  18. 45webStable Diffusion web UI10 November 2022
  19. 46citationinvisible-watermarkShield Mountain — 2022-11-02
  20. 49arxivBoomerang: Local sampling on image manifolds using diffusion modelsLorenzo Luzi et al. — 2022-10-21
  21. 50webStable Diffusion Based Image CompressionMatthias Bühlmann — 2022-09-28
  22. 51arxivAdding Conditional Control to Text-to-Image Diffusion ModelsLvmin Zhang — 10 February 2023
  23. 55webStability AI is open-sourcing its DreamStudio web appJess Weatherbed — 17 May 2023
  24. 59webComfyUI
  25. 60thesisLatent Auto-recursive Composition EngineYenkai Huang — Dartmouth College — 2024-05-10
  26. 61webCompVis (CompVis)2023-08-23
  27. 68arxivSDXL: Improving Latent Diffusion Models for High-Resolution Image SynthesisDustin Podell et al. — 2023-07-04
  28. 73arxivLearning Transferable Visual Models From Natural Language SupervisionAlec Radford et al. — 2021-02-26
  29. 74arxivSDEdit: Guided Image Synthesis and Editing with Stochastic Differential EquationsChenlin Meng et al. — 2022-01-04
  30. 75bookProceedings of the IEEE/CVF Conference on Computer Vision and Pattern Recognition (CVPR)Robin Rombach et al. — 2022
  31. 94webCommunity License2024-07-05
  32. 96conferenceHigh-Resolution Image Synthesis with Latent Diffusion ModelsRombach et al. — June 2022
  33. 98webAnyone can use this AI art generator — that's the riskJames Vincent — 15 September 2022