ComfyUI/comfy_extras/nodes_differential_diffusion.py

# code adapted from https://github.com/exx8/differential-diffusion

import torch

class DifferentialDiffusion():
    @classmethod
    def INPUT_TYPES(s):
        return {
            "required": {
                "model": ("MODEL", ),
            },
            "optional": {
                "strength": ("FLOAT", {
                    "default": 1.0,
                    "min": 0.0,
                    "max": 1.0,
                    "step": 0.01,
                }),
            }
        }
    RETURN_TYPES = ("MODEL",)
    FUNCTION = "apply"
    CATEGORY = "_for_testing"
    INIT = False

    def apply(self, model, strength=1.0):
        model = model.clone()
        model.set_model_denoise_mask_function(lambda *args, **kwargs: self.forward(*args, **kwargs, strength=strength))
        return (model, )

    def forward(self, sigma: torch.Tensor, denoise_mask: torch.Tensor, extra_options: dict, strength: float):
        model = extra_options["model"]
        step_sigmas = extra_options["sigmas"]
        sigma_to = model.inner_model.model_sampling.sigma_min
        if step_sigmas[-1] > sigma_to:
            sigma_to = step_sigmas[-1]
        sigma_from = step_sigmas[0]

        ts_from = model.inner_model.model_sampling.timestep(sigma_from)
        ts_to = model.inner_model.model_sampling.timestep(sigma_to)
        current_ts = model.inner_model.model_sampling.timestep(sigma[0])

        threshold = (current_ts - ts_to) / (ts_from - ts_to)

        # Generate the binary mask based on the threshold
        binary_mask = (denoise_mask >= threshold).to(denoise_mask.dtype)

        # Blend binary mask with the original denoise_mask using strength
        if strength and strength < 1:
            blended_mask = strength * binary_mask + (1 - strength) * denoise_mask
            return blended_mask
        else:
            return binary_mask


NODE_CLASS_MAPPINGS = {
    "DifferentialDiffusion": DifferentialDiffusion,
}
NODE_DISPLAY_NAME_MAPPINGS = {
    "DifferentialDiffusion": "Differential Diffusion",
}