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Investigating and Simplifying Masking-based Saliency Methods for Model Interpretability

This repository contains code for running and replicating the experiments from Investigating and Simplifying Masking-based Saliency Methods for Model Interpretability. It is a modified fork of Classifier-Agnostic Saliency Map Extraction, and contains the code originally forked from the ImageNet training in PyTorch.

(A) Overview of the training setup for our final model. The masker is trained to maximize masked-in classification accuracy and masked-out prediction entropy.
(B) Masker architecture. The masker takes as input the hidden activations of different layers of the ResNet-50 and produces a mask of the same resolution as the input image.
(C) Few-shot training of masker. Performance drops only slightly when trained on much fewer examples compared to the full training procedure.

Software requirements

• This repository requires Python 3.7 or later.
• Experiments were run with the following library versions:

pytorch==1.4.0
torchvision==0.5.0
opencv-python==4.1.2.30
beautifulsoup4==4.8.1
tqdm==4.35.0
pandas==0.24.2
scikit-learn==0.20.2
scipy==1.3.0 

In addition, git clone https://github.com/zphang/zutils and add it to your PYTHONPATH

Additional requirements

• If you want to use the PxAP metric from Evaluating Weakly Supervised Object Localization Methods Right:
  • git clone https://github.com/clovaai/wsolevaluation and add it to your PYTHONPATH. To avoid potential naming conflicts, add it to the front of your PYTHONPATH.
  • pip install munch (as well as any other requirements listed here)
• If you want to run the Grad-CAM and Guided-backprop saliency methods:
  • pip install torchray, or git clone https://github.com/facebookresearch/TorchRay and add it to your PYTHONPATH
• If you want to use the CA-GAN infiller from Generative Image Inpainting with Contextual Attention
  • git clone https://github.com/daa233/generative-inpainting-pytorch and add it to your PYTHONPATH
  • Download the linked pretrained model for PyTorch, and set environment variable CA_MODEL_PATH to point to it
• If you want to use the DFNet infiller from https://arxiv.org/abs/1904.08060
  • git clone https://github.com/hughplay/DFNet and add it to your PYTHONPATH
  • Download the linked pretrained model for PyTorch, and set environment variable DFNET_MODEL_PATH to point to it. Use the Places 2 model.

Data requirements

• ImageNet dataset should be stored in IMAGENET_PATH path and set up in the usual way (separate train and val folders with 1000 subfolders each). See this repo for detailed instructions how to download and set up the dataset.
• ImageNet bounding box annotations should be in IMAGENET_ANN directory that contains 50000 files named ILSVRC2012_val_<id>.xml where <id> is the validation image id (for example ILSVRC2012_val_00050000.xml). It may be simply obtained by unzipping the official validation bounding box annotations archive to IMAGENET_ANN directory.
• Bounding box annotations for parts of the training set can downloaded from here. This will be used for our Train-Validation set.
• If want to use the PxAP metrics from Evaluating Weakly Supervised Object Localization Methods Right:
  • Download the relevant datasets in described here

Running the code

We will assume that experiments will be run in the following folder:

export EXP_DIR=/path/to/experiments

Data Preparation

To facilitate easy subsetting and label shuffling for the ImageNet training set, we write a JSON files containing the paths to the example images, and their corresponding labels. These will be consumed by a modified ImageNet PyTorch Dataset.

Run the following command:

python casme/tasks/imagenet/preproc.py \
    --train_path ${IMAGENET_PATH}/train \
    --val_path ${IMAGENET_PATH}/val \
    --val_annotation_path ${IMAGENET_ANN}/val \
    --output_base_path ${EXP_DIR}/metadata

This script does several things:

• Packages the ImageNet Train and Validation image data and labels into metadata JSON files (train.json, val.json)
• Splits the train data into Train-Train and Train-Validation subsets (train_train.json, train_val.json)
• Generates a shuffled version of the Train JSON (train_shuffle.json) for DRT Sanity Check
• Also packages the bounding box annotation for the Validation set into JSON files (val_bboxes.json)
• Optionally, to use bounding boxes for the Train-Validation set, unzip the downloaded data from here, and provided an additional argument --extended_annot_base_path. (train_val_bboxes.json)

Training

To train a FIX or CA model, you can run:

python train_casme.py \
    --train_json ${EXP_DIR}/metadata/train.json \
    --val_json ${EXP_DIR}/metadata/val.json \
    --ZZsrc ./assets/fix.json \
    --masker_use_layers 3,4 \
    --output_path ${EXP_DIR}/runs/ \
    --epochs 60 --lrde 20 \
    --name fix

python train_casme.py \
    --train_json ${EXP_DIR}/metadata/train.json \
    --val_json ${EXP_DIR}/metadata/val.json \
    --ZZsrc ./assets/ca.json \
    --masker_use_layers 3,4 \
    --output_path ${EXP_DIR}/runs/ \
    --epochs 60 --lrde 20 \
    --name ca

• The --ZZsrc arguments provide JSON files with additional options for the command-line interface. ./assets/fix.json and ./assets/ca.json contain options and final hyper-parameters chosen for the FIX and CA models in the paper.
• We also only use the 4th and 5th layers from the classifier in the masker model.
• --train_json and --val_json point to the JSON files containing the paths to the example images, and their corresponding labels, described above.

Evaluation

To evaluate the model on WSOL metrics and Saliency Metric, run:

python casme/tasks/imagenet/score_bboxes.py \
    --val_json ${EXP_DIR}/metadata/val.json \
    --mode casme \
    --bboxes_path ${EXP_DIR}/metadata/val_bboxes.json \
    --casm_path ${EXP_DIR}/runs/ca/epoch_XXX.chk \
    --output_path ${EXP_DIR}/runs/ca/metrics/scores.json

where epoch_XXX.chk corresponds to the model checkpoint you want to evaluate. Chain the val_json and bboxes_path paths to evaluate on the Train-Validation or Validation sets respectively. Note that the mode should be casme regardless of whether you are using FIX or CA models.

The output JSON looks something like this:

{
  "F1": 0.6201832851563015,
  "F1a": 0.5816041554785251,
  "OM": 0.48426,
  "LE": 0.35752,
  "SM": 0.523097248590095,
  "SM1": -0.5532185246243142,
  "SM2": -1.076315772478443,
  "top1": 75.222,
  "top5": 92.488,
  "sm_acc": 74.124,
  "binarized": 0.4486632848739624,
  "avg_mask": 0.44638757080078123,
  "std_mask": 0.1815464876794815,
  "entropy": 0.034756517103545534,
  "tv": 0.006838996527194977
}

• OM, LE, F1, SM and avg_mask correspond to the respective columns in Table 1.
• For a given image, an F1-score is compute for each of the bounding boxes. F1 takes the max while F1a takes the mean F1-score for all boxes in the image, and the result is averaged over all the images in the dataset.
• SM1 and SM2 refer to the first and second terms of the Saliency Metric formulation. sm_acc is the top-1 accuracy under the crop-and-scale transformation for the Saliency Metric.
• Top 1 and Top 5 are the accuracies of the classifier.
• Binarized the is average over the binarized mask pixels over the whole dataset. std_mask is the Standard deviation of the continuous mask pixels over the dataset.
• TV is the total variation, entropy is the entropy over predictions for masked imaged.

To evaluate the model on PxAP, run:

python casme/tasks/imagenet/wsoleval.py \
    --cam_loader casme \
    --casm_base_path ${EXP_DIR}/runs/ca/epoch_XXX.chk \
    --casme_load_mode specific \
    --dataset OpenImages \
    --dataset_split test \
    --dataset_path ${WSOLEVAL_PATH}/dataset \
    --metadata_path ${WSOLEVAL_PATH}/metadata \
    --output_base_path ${EXP_DIR}/runs/ca/metrics/scores.json

where WSOLEVAL_PATH is the location where wsolevaluation has been cloned to, and after running the relevant dataset downloading scripts.

Pretrained Checkpoints

• fix.chk corresponds to our best-performing FIX model (Row I of Table 1).
• ca.chk corresponds to our best-performing CA model (Row J of Table 1).

Reference

If you found this code useful, please cite the following paper:

Jason Phang, Jungkyu Park, Krzysztof J. Geras "Investigating and Simplifying Masking-based Saliency Methods for Model Interpretability." arXiv preprint arXiv:2010.09750 (2020).

@article{phang2020investigating,
  title={Investigating and Simplifying Masking-based Saliency Methods for Model Interpretability},
  author={Phang, Jason and Park, Jungkyu and Geras, Krzysztof J},
  journal={arXiv preprint arXiv:2010.09750},
  year={2020}
}