---
tags:
- text-to-image
- comfyui
- prxpixel
- fp8
- safetensors
- custom-inference
pipeline_tag: text-to-image
base_model:
- Photoroom/prxpixel-t2i
---

# PRX Pixel FP8 Mixed Transformer

This repository contains a **single-file PRX Pixel transformer checkpoint** converted from `Photoroom/prxpixel-t2i` into a **mixed fp8 safetensors** format for the `lumina_prx_pixel` custom ComfyUI runtime.

## What This File Is

- This is **not** the full original model repo.
- This file contains the **transformer only**.
- The **tokenizer** and **text encoder / clip side** should still be loaded from the original base model source:
  `Photoroom/prxpixel-t2i`

## Mixed FP8 Means

This checkpoint uses a **mixed fp8 storage recipe**, not full end-to-end fp8 for every tensor.

- Large transformer projection weights are stored in `float8_e4m3fn`
- More sensitive tensors stay in higher precision
- Runtime is **mixed precision**
  fp8 weights are used for selected large linear layers, while activations / outputs remain in bf16 or the loader compute dtype

In other words:

- **weight storage** is reduced for selected heavy layers
- **compute** is still mixed, not pure fp8 everywhere

## Intended Runtime

This file is intended for:

- `lumina_prx_pixel`
- `Load PRX Pixel model`
- `Load prx clip model only`

from the matching custom ComfyUI node pack.

It is **not meant for stock diffusers loading**.

## How To Use In ComfyUI

1. Place the `.safetensors` file inside `ComfyUI/models/diffusion_models` or `ComfyUI/models/unet`
2. Load it with `Load PRX Pixel model`
3. Load the text side with `Load prx clip model only`
4. Set that clip source to `Photoroom/prxpixel-t2i`
5. Connect both into `lumina_prx_pixel`

## Runtime Notes

- For the real fp8 matmul path, you want a CUDA setup with fp8 support in PyTorch
- On unsupported backends, the runtime may fall back to dequantized math for execution
- This is still useful for packaging and selective storage reduction, but the best VRAM win is on supported CUDA fp8 paths

## Conversion Notes

This file was produced from the original PRX Pixel transformer shards and packed into a custom single-file format used by the local runtime.

The embedded metadata includes:

- transformer config
- scheduler config
- PRX Pixel generation settings
- fp8 scale metadata for converted layers

## Limitations

- This is a converted checkpoint, not an original upstream release artifact
- Output quality and numerical behavior can differ slightly from the source bf16 weights
- Compatibility is tied to the custom `lumina_prx_pixel` runtime that knows how to read this format

## Credit

- Base model: `Photoroom/prxpixel-t2i`
- FP8 mixed single-file packaging and runtime support: `Lumnatrix`