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32da3e8 | 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 | """LPIPS evaluator for paired (generated, ground-truth) images. Used for nav eval."""
import numpy as np
import torch
class LPIPSEvaluator:
"""Lazy-loaded LPIPS model for image-pair perceptual distance.
Uses the `lpips` PyPI package (AlexNet backbone by default).
"""
def __init__(self, device: str = "cuda", net: str = "alex"):
self.model = None
self.device = device
self.net = net
def _ensure_loaded(self):
if self.model is None:
import lpips # noqa: WPS433
self.model = lpips.LPIPS(net=self.net).to(self.device).eval()
for p in self.model.parameters():
p.requires_grad_(False)
@torch.no_grad()
def compute_batch_scores(self, gen_np: np.ndarray, gt_np: np.ndarray) -> torch.Tensor:
"""LPIPS distance per pair.
Args:
gen_np: [B, H, W, C] uint8
gt_np: [B, H, W, C] uint8
Returns:
Tensor of shape [B] with LPIPS distances.
"""
self._ensure_loaded()
gen = torch.from_numpy(gen_np).permute(0, 3, 1, 2).float().div(255.0).mul(2).sub(1).to(self.device)
gt = torch.from_numpy(gt_np).permute(0, 3, 1, 2).float().div(255.0).mul(2).sub(1).to(self.device)
return self.model(gen, gt).flatten().cpu()
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