denoiser_scaling.py

# SPDX-FileCopyrightText: Copyright (c) 2025 NVIDIA CORPORATION & AFFILIATES. All rights reserved.
# SPDX-License-Identifier: Apache-2.0
#
# Licensed under the Apache License, Version 2.0 (the "License");
# you may not use this file except in compliance with the License.
# You may obtain a copy of the License at
#
# http://www.apache.org/licenses/LICENSE-2.0
#
# Unless required by applicable law or agreed to in writing, software
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from typing import Tuple

import torch


class EDMScaling:
    def __init__(self, sigma_data: float = 0.5):
        self.sigma_data = sigma_data

    def __call__(self, sigma: torch.Tensor) -> Tuple[torch.Tensor, torch.Tensor, torch.Tensor, torch.Tensor]:
        c_skip = self.sigma_data**2 / (sigma**2 + self.sigma_data**2)
        c_out = sigma * self.sigma_data / (sigma**2 + self.sigma_data**2) ** 0.5
        c_in = 1 / (sigma**2 + self.sigma_data**2) ** 0.5
        c_noise = 0.25 * sigma.log()
        return c_skip, c_out, c_in, c_noise