# candle-stable-diffusion-3: Candle Implementation of Stable Diffusion 3/3.5
*A cute rusty robot holding a candle torch in its hand, with glowing neon text \"LETS GO RUSTY\" displayed on its chest, bright background, high quality, 4k*, generated by Stable Diffusion 3 Medium
Stable Diffusion 3 Medium is a text-to-image model based on Multimodal Diffusion Transformer (MMDiT) architecture.
- [huggingface repo](https://huggingface.co/stabilityai/stable-diffusion-3-medium)
- [research paper](https://arxiv.org/pdf/2403.03206)
- [announcement blog post](https://stability.ai/news/stable-diffusion-3-medium)
Stable Diffusion 3.5 is a family of text-to-image models with latest improvements:
- [announcement blog post](https://stability.ai/news/introducing-stable-diffusion-3-5)
It has three variants:
- [Stable Diffusion 3.5 Large](https://huggingface.co/stabilityai/stable-diffusion-3.5-large) @ 8.1b params, with scaled and slightly modified MMDiT architecture.
- [Stable Diffusion 3.5 Large Turbo](https://huggingface.co/stabilityai/stable-diffusion-3.5-large-turbo) distilled version that enables 4-step inference.
- [Stable Diffusion 3.5 Medium](https://huggingface.co/stabilityai/stable-diffusion-3.5-medium) @ 2.5b params, with improved MMDiT-X architecture.
## Getting access to the weights
The weights of Stable Diffusion 3/3.5 is released by Stability AI under the Stability Community License. You will need to accept the conditions and acquire a license by visiting the repos on HuggingFace Hub to gain access to the weights for your HuggingFace account.
To allow your computer to gain access to the public-gated repos on HuggingFace, you might need to create a [HuggingFace User Access Tokens](https://huggingface.co/docs/hub/en/security-tokens) (recommended) and log in on your computer if you haven't done that before. A convenient way to do the login is to use [huggingface-cli](https://huggingface.co/docs/huggingface_hub/en/guides/cli):
```shell
huggingface-cli login
```
and you will be prompted to enter your token.
On the first run, the weights will be automatically downloaded from the Huggingface Hub. After the download, the weights will be [cached](https://huggingface.co/docs/datasets/en/cache) and remain accessible locally.
## Running the model
```shell
cargo run --example stable-diffusion-3 --release --features=cuda -- \
--which 3-medium --height 1024 --width 1024 \
--prompt 'A cute rusty robot holding a candle torch in its hand, with glowing neon text \"LETS GO RUSTY\" displayed on its chest, bright background, high quality, 4k'
```
To use different models, changed the value of `--which` option. (Possible values: `3-medium`, `3.5-large`, `3.5-large-turbo` and `3.5-medium`).
To display other options available,
```shell
cargo run --example stable-diffusion-3 --release --features=cuda -- --help
```
If GPU supports, Flash-Attention is a strongly recommended feature as it can greatly improve the speed of inference, as MMDiT is a transformer model heavily depends on attentions. To utilize [candle-flash-attn](https://github.com/huggingface/candle/tree/main/candle-flash-attn) in the demo, you will need both `--features flash-attn` and `--use-flash-attn`.
```shell
cargo run --example stable-diffusion-3 --release --features=cuda,flash-attn -- --use-flash-attn ...
```
## Performance Benchmark
Below benchmark is done with Stable Diffusion 3 Medium by generating 1024-by-1024 image from 28 steps of Euler sampling and measure the average speed (iteration per seconds).
[candle](https://github.com/huggingface/candle) and [candle-flash-attn](https://github.com/huggingface/candle/tree/main/candle-flash-attn) is based on the commit of [0d96ec3](https://github.com/huggingface/candle/commit/0d96ec31e8be03f844ed0aed636d6217dee9c7bc).
System specs (Desktop PCIE 5 x8/x8 dual-GPU setup):
- Operating System: Ubuntu 23.10
- CPU: i9 12900K w/o overclocking.
- RAM: 64G dual-channel DDR5 @ 4800 MT/s
| RTX 3090 Ti | 0.83 | 2.15 |
| RTX 4090 | 1.72 | 4.06 |