detect_anomaly.py

import torch
import numpy as np
from PIL import Image
import torchvision.transforms as T
from train_autoencoder import ConvAutoencoder

device = torch.device("cuda" if torch.cuda.is_available() else "cpu")
model = ConvAutoencoder().to(device)
model.load_state_dict(torch.load("models/autoencoder.pth", map_location=device))
model.eval()

transform = T.Compose([
    T.Resize((224, 224)),
    T.ToTensor(),
    T.Normalize(mean=[0.485, 0.456, 0.406], std=[0.229, 0.224, 0.225]),
])

def detect_hazard(img_pil):
    """
    Returns: (is_anomalous: bool, recon_error: float, reconstructed_img: PIL)
    """
    img_tensor = transform(img_pil).unsqueeze(0).to(device)

    with torch.no_grad():
        recon = model(img_tensor)
        loss_fn = torch.nn.MSELoss()
        recon_error = loss_fn(recon, img_tensor).item()

    # Convert recon to PIL
    recon_pil = recon.cpu().squeeze(0)
    recon_pil = T.ToPILImage()(recon_pil)

    # Threshold (adjust based on validation)
    is_anomalous = recon_error > 0.02

    return is_anomalous, recon_error, recon_pil