47 lines
2.3 KiB
Python
47 lines
2.3 KiB
Python
# Copyright (c) 2021, NVIDIA CORPORATION & AFFILIATES. All rights reserved.
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#
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# NVIDIA CORPORATION and its licensors retain all intellectual property
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# and proprietary rights in and to this software, related documentation
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# and any modifications thereto. Any use, reproduction, disclosure or
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# distribution of this software and related documentation without an express
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# license agreement from NVIDIA CORPORATION is strictly prohibited.
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"""Kernel Inception Distance (KID) from the paper "Demystifying MMD
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GANs". Matches the original implementation by Binkowski et al. at
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https://github.com/mbinkowski/MMD-GAN/blob/master/gan/compute_scores.py"""
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import numpy as np
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from . import metric_utils
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#----------------------------------------------------------------------------
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def compute_kid(opts, max_real, num_gen, num_subsets, max_subset_size):
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# Direct TorchScript translation of http://download.tensorflow.org/models/image/imagenet/inception-2015-12-05.tgz
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detector_url = 'https://api.ngc.nvidia.com/v2/models/nvidia/research/stylegan3/versions/1/files/metrics/inception-2015-12-05.pkl'
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detector_kwargs = dict(return_features=True) # Return raw features before the softmax layer.
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real_features = metric_utils.compute_feature_stats_for_dataset(
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opts=opts, detector_url=detector_url, detector_kwargs=detector_kwargs,
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rel_lo=0, rel_hi=0, capture_all=True, max_items=max_real).get_all()
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gen_features = metric_utils.compute_feature_stats_for_generator(
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opts=opts, detector_url=detector_url, detector_kwargs=detector_kwargs,
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rel_lo=0, rel_hi=1, capture_all=True, max_items=num_gen).get_all()
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if opts.rank != 0:
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return float('nan')
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n = real_features.shape[1]
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m = min(min(real_features.shape[0], gen_features.shape[0]), max_subset_size)
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t = 0
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for _subset_idx in range(num_subsets):
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x = gen_features[np.random.choice(gen_features.shape[0], m, replace=False)]
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y = real_features[np.random.choice(real_features.shape[0], m, replace=False)]
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a = (x @ x.T / n + 1) ** 3 + (y @ y.T / n + 1) ** 3
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b = (x @ y.T / n + 1) ** 3
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t += (a.sum() - np.diag(a).sum()) / (m - 1) - b.sum() * 2 / m
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kid = t / num_subsets / m
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return float(kid)
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#----------------------------------------------------------------------------
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