Tutorial gradCAM 3D seems to have inverted heatmap #1796

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1. KumoLiu commented on Aug 22, 2024

   

   KumoLiu

   on Aug 22, 2024

   Contributor

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   Hi @CamilleDelgrange, thanks for your interest here.
   Yes, the default_normalizer used in GradCam will flip magnitudes.
   https://github.com/Project-MONAI/MONAI/blob/dev/monai/visualize/class_activation_maps.py#L37

   You can simply modify it by adding a customized normalizer.

   def custom_normalizer(x):
       def _compute(data):
           scaler = ScaleIntensity(minv=0.0, maxv=1.0)
           return np.stack([scaler(i) for i in data], axis=0)
       if isinstance(x, torch.Tensor):
           return torch.as_tensor(_compute(x.detach().cpu().numpy()), device=x.device)
       return _compute(x)
   
   monai.visualize.GradCAM(nn_module=model_3d, target_layers="class_layers.relu", postprocessing=custom_normalizer)
   

   Hope it helps, thanks.
2. Project-MONAI

   locked and limited conversation to collaborators on Aug 22, 2024
3. KumoLiu

   converted this issue into a discussion #1797 on Aug 22, 2024