prx-pixel-fp8

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