MOSS-Image Base DiT, INT8 (GPTQ, ConvRot)
The DiT of MOSS-Image Base in one 5.04 GiB file, with the 252 block linears in int8. Generation at 1024² peaks at 6.3 GiB against 10.7 GiB in bf16, and denoises in 11–15 s against 21.6 s.
| File | moss_image_base_int8_gptq.safetensors (5.04 GiB: 4.43 GiB int8, 0.60 GiB bf16) |
| Quantized | layers.N.proj.{q,k,v,o,ffn_up_gate,ffn_down}: each weight rotated per 256-column group by a Hadamard matrix (ConvRot), int8 with one fp32 weight_scale per output row |
| Kept in bf16 | everything else: embedders, modulation, norms, head |
| Format | ComfyUI's int8_tensorwise + convrot layout. Loading it in ComfyUI has not been tested |
| Base only | made from MOSS-Image Base; SFT has no file |
How it was made
Offline GPTQ (block 128, damping 0.01, activation-ordered), one block at a time, each quantized block feeding the next. Calibration: 233 images, t2i and i2i together, 466 samples (with its caption, and with the empty prompt skipping block 22, as CFG does) at σ drawn from the 50-step, shift-5 inference schedule.
The header's base_fingerprint ties the file to that DiT, and int8_id identifies its
int8 tensors.
Measured
RTX 5070 Ti 16 GB. Generation, one render per arm (ER-SDE 50 steps + Spectrum, CFG 3, seed 7, compiled, all blocks resident):
| job | arm | denoise | peak |
|---|---|---|---|
| t2i 1024² | bf16 | 21.6 s | 10.7 GiB |
| t2i 1024² | int8 GPTQ | 11.3 s | 6.3 GiB |
| t2i 1024² | int8 GPTQ, fp32 stream | 15.1 s | 7.8 GiB |
| i2i 1216×864, full-size reference | bf16 | 29.1 s | 13.0 GiB |
| i2i 〃 | int8 GPTQ | 27.7 s | 8.6 GiB |
| i2i 〃 | int8 GPTQ, fp32 stream | 27.7 s | 11.2 GiB |
Read int8 generation as 11–15 s: round-to-nearest int8 runs the same kernels and took 15.0 s, so that gap is run-to-run noise.
Prediction error ‖v − v_fp32‖ / ‖v_fp32‖ in %, on images outside calibration (t2i six
images; i2i 12 pairs, centre-cropped to 48×48):
| σ | bf16 | int8 GPTQ | GPTQ, fp32 stream | |
|---|---|---|---|---|
| t2i | 0.1 | 4.81 | 5.93 | 3.85 |
| t2i | 0.5 | 1.93 | 2.43 | 1.71 |
| t2i | 0.9 | 2.08 | 2.30 | 1.34 |
| i2i | 0.1 | 3.61 | 4.50 | 3.52 |
| i2i | 0.5 | 2.30 | 2.84 | 2.17 |
| i2i | 0.9 | 2.05 | 2.24 | 1.19 |
Alone, this file is less accurate than bf16. On an fp32 residual stream it sits below bf16 at every σ tested.
Not measured
- A complete LoRA trained on this base. Training on it has stopped at 60 steps, on one set.
- A multi-seed render A/B against bf16.
- i2i error beyond
sanitizecrops.
Refused or unsupported
Written for anima_lora, whose int8 entry points
refuse block swap (the offloader moves .weight, not the int8 copies) and LoHa (it builds
W + ΔW against the base weight). LoRA and LoKr run, and a LoRA trained on bf16 loads on
this base.
License: Apache-2.0, as MOSS-Image.