feat: add shift factor support

[leejet]

.\bin\Release\sd.exe --diffusion-model  ..\models\flux1-dev-q8_0.gguf --vae ..\..\ComfyUI\models\vae\ae.sft --clip_l ..\..\ComfyUI\models\clip\clip_l.safetensors --t5xxl ..\..\ComfyUI\models\clip\t5-v1_1-xxl-encoder-Q8_0.gguf  -p "a lovely cat holding a sign says 'flux.cpp'" --cfg-scale 1.0 --sampling-method euler -v

Without shift factor

With shift factor

[Green-Sky]

Seems to slightly reduce the vertical lines, but hard to tell.
Maybe test with less steps or lower quant?

[stduhpf]

[Green-Sky]

diff boosted

animated:


(a -> after, b -> before)

[stduhpf]

Looks to have about the same diff as VAE tiling on vs off, maybe even less

[leejet]

I didn’t really pay attention to the differences in the vertical lines — the purpose of this PR is simply to follow the official pipeline and include the handling of the shift factor.

[Green-Sky]

I didn’t really pay attention to the differences in the vertical lines — the purpose of this PR is simply to follow the official pipeline and include the handling of the shift factor.

I figured as much, bit it still lowers the vertical line artifacts a bit. At least with that limited testing. I'm currently looking into chroma.