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_pixelLoad PRX Pixel modelLoad prx clip model only
from the matching custom ComfyUI node pack.
It is not meant for stock diffusers loading.
How To Use In ComfyUI
- Place the
.safetensors file inside ComfyUI/models/diffusion_models or ComfyUI/models/unet
- Load it with
Load PRX Pixel model
- Load the text side with
Load prx clip model only
- Set that clip source to
Photoroom/prxpixel-t2i
- 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
