To debug encoder-decoder bottlenecks in image captioning models for complex scenes, analyze attention maps, gradient flow, and feature activations using visualization techniques and layer-wise relevance propagation.
Here is the code snippet you can refer to:

In the above, we are using the following key points:
- Model Selection: Uses a pre-trained ResNet50 as the encoder for feature extraction.
- Grad-CAM Implementation: Captures activations and gradients from a target layer to analyze feature importance.
- Image Preprocessing: Normalizes and resizes the input image to match the model's expected format.
- Heatmap Generation: Computes Grad-CAM and overlays the attention heatmap on the original image.
- Visualization: Displays the overlayed heatmap to identify bottlenecks in scene understanding.
Hence, by leveraging Grad-CAM visualization, we can effectively debug encoder-decoder bottlenecks in image captioning models, helping to improve attention mechanisms for complex scenes.