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"""
Credit: ComfyUI
https://github.com/comfyanonymous/ComfyUI/blob/v0.3.7/comfy_extras/nodes_model_advanced.py#L257
"""
import gradio as gr
import torch
from modules import scripts
from modules.infotext_utils import PasteField
from modules.shared import opts
class ScriptRescaleCFG(scripts.ScriptBuiltinUI):
section = "cfg"
create_group = False
def title(self):
return "RescaleCFG"
def show(self, is_img2img):
return scripts.AlwaysVisible if opts.show_rescale_cfg else None
def ui(self, is_img2img):
cfg = gr.Slider(
value=0.0,
minimum=0.0,
maximum=1.0,
step=0.05,
label="Rescale CFG",
elem_id=f"{'img2img' if is_img2img else 'txt2img'}_rescale_cfg_scale",
scale=4,
)
self.infotext_fields = [PasteField(cfg, "Rescale CFG", api="rescale_cfg")]
return [cfg]
def after_extra_networks_activate(self, p, cfg, *args, **kwargs):
if opts.show_rescale_cfg and cfg > 0.0:
p.extra_generation_params.update({"Rescale CFG": cfg})
def process_before_every_sampling(self, p, cfg, *args, **kwargs):
if not opts.show_rescale_cfg or cfg < 0.05:
return
@torch.inference_mode()
def rescale_cfg(args):
cond = args["cond"]
uncond = args["uncond"]
cond_scale = args["cond_scale"]
sigma = args["sigma"]
sigma = sigma.view(sigma.shape[:1] + (1,) * (cond.ndim - 1))
x_orig = args["input"]
x = x_orig / (sigma * sigma + 1.0)
cond = ((x - (x_orig - cond)) * (sigma**2 + 1.0) ** 0.5) / (sigma)
uncond = ((x - (x_orig - uncond)) * (sigma**2 + 1.0) ** 0.5) / (sigma)
x_cfg = uncond + cond_scale * (cond - uncond)
ro_pos = torch.std(cond, dim=(1, 2, 3), keepdim=True)
ro_cfg = torch.std(x_cfg, dim=(1, 2, 3), keepdim=True)
x_rescaled = x_cfg * (ro_pos / ro_cfg)
x_final = cfg * x_rescaled + (1.0 - cfg) * x_cfg
return x_orig - (x - x_final * sigma / (sigma * sigma + 1.0) ** 0.5)
unet = p.sd_model.forge_objects.unet.clone()
unet.set_model_sampler_cfg_function(rescale_cfg)
p.sd_model.forge_objects.unet = unet
print(f"rescale_cfg = {cfg}")
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