Interpretable Generative Models through Post-hoc Concept Bottlenecks (CVPR 2025)

Paper | Project Page

This is the official repository for the CVPR 2025 paper: Interpretable Generative Models through Post-hoc Concept Bottlenecks

• We propose two novel methods to enable interpretability for generative models:
  • CB-AE: The 1st method for post-hoc interpretable generative models. CB-AE can be trained efficiently with a frozen pretrained generative model, without real concept-labeled images.
  • Concept Controller: An optimization-based concept intervention method with improved steerability and higher image quality.
• We show our methods have higher steerability (+31% and +28% better than prior SOTA) and lower cost (4-15x faster to train) on deep generative models including GANs and diffusion models.

Table of Contents

• Setup
  • Environment setup instructions
  • Download base model and CB-AE/CC weights
  • Download concept classifier weights
• Demo
• Training
• Evaluation
• Results
• Sources
• Cite this work

Setup

Environment setup instructions

• Conda environment installation:

  conda create -n posthocgencbm python=3.8
  conda install nvidia/label/cuda-11.7.0::cuda-nvcc cudatoolkit
  pip install torch==1.13.1+cu117 torchvision==0.14.1+cu117 torchaudio==0.13.1 --extra-index-url https://download.pytorch.org/whl/cu117
  pip install -r requirements.txt
  

• Download the CelebA-HQ-pretrained StyleGAN2 base model from below and test the environment using python3 eval/test_stygan2.py. It should save a StyleGAN2 generated image in images/. If you get CUDA runtime errors (during "Setting up PyTorch plugin..."), use this:

  export CUDA_HOME=$CONDA_PREFIX
  export CPLUS_INCLUDE_PATH=$CUDA_HOME/include:$CPLUS_INCLUDE_PATH
  export LIBRARY_PATH=$CUDA_HOME/lib:$LIBRARY_PATH
  

Download base model and CB-AE/CC weights

• We use models/checkpoints for saving/loading CB-AE/CC checkpoints

  mkdir models/checkpoints
  cd models/checkpoints
  

• CelebA-HQ-pretrained StyleGAN2 (from [2]):

  ## base model weights
  wget https://api.ngc.nvidia.com/v2/models/nvidia/research/stylegan2/versions/1/files/stylegan2-celebahq-256x256.pkl
  ## CB-AE weights
  gdown https://drive.google.com/uc?id=1RBdjcBDbpAoW5qOkG-rBonIpcBApBF-q
  ## CC weights
  gdown https://drive.google.com/uc?id=1fh2XV2ttrCc88-SgfR9f-JcwG1eent_U
  

• CelebA-HQ-pretrained DDPM-256x256 (from [3]):

  ## base model weights get downloaded automatically via HuggingFace when using "-e cbae_ddpm" (i.e. any config using this DDPM model)
  ## CB-AE weights
  gdown https://drive.google.com/uc?id=1kl5pDqzm0M73r8H74AfSokgDFGAF0szb
  

Download concept classifier weights

• ResNet18-based classifiers for training and visualization.
• ViT-L-16-based classifiers for quantitative evaluation.

  cd models/checkpoints
  ## ResNet18
  gdown https://drive.google.com/uc?id=1xbR7MbERV7wMnU4WcsNSDriYXBqsy_jZ
  unzip celebahq_rn18_conclsf.zip
  ## ViT-L-16 (relatively large file of ~8.4 GB, so download only if you want to do evaluations)
  gdown https://drive.google.com/uc?id=1XD6Badmf4QwRrdy6MbOr-mefyu1k_OIy
  unzip celebahq_vitl16_conclsf.zip
  

Demo

• Follow notebooks/visualize_interventions.ipynb for concept interventions demo with CelebA-HQ-pretrained StyleGAN2 with CB-AE.
  • Note: Before the notebook, please download concept classifier weights (ResNet18) for visualization.

Training

• Use bash scripts/train_cbae.sh to train a CB-AE for a CelebA-HQ-pretrained StyleGAN2 with supervised classifiers as pseudo-label source.
• Some important arguments to specify are:
  • -e: specify which config file from the config/ folder to use (e.g. cbae_stygan2).
  • -d: specify dataset of base generative model (e.g. celebahq).
  • -t: specify experiment name to be used as a suffix for saving logs, checkpoints, etc.
  • -p: specify pseudo-label source $M$ for CB-AE/CC training (e.g. supervised for supervised-trained classifiers, clipzs for zero-shot CLIP classifiers, tipzs for few-shot adapted CLIP).
• The same train_cbae.sh has commented out examples for training Concept Controller (CC).

Evaluation

• Use bash scripts/eval_intervention.sh for an example that runs steerability evaluation for Smiling concept for a CelebA-HQ StyleGAN2 CB-AE.
• Some important arguments to specify are:
  • -e, -d, and -t should be the same as from training (or use based on downloaded CB-AE/CC checkpoint, e.g. celebahq_cbae_stygan2_thr90_sup_pl_cls8_cbae.pt would use -d celebahq -e cbae_stygan2_thr90 -t sup_pl_cls8).
  • -c: concept to intervene on (e.g. Smiling or Mouth_Slightly_Open).
  • -v: desired concept value (e.g. 0 or 1 based on if desired target concept is Smiling or Not Smiling).
  • --optint: use this for optimization-based interventions (not using this will use CB-AE interventions).
  • --visualize: use this to visualize some examples (not using this will run the full quantitative evaluation).
• The same eval_intervention.sh has commented out examples for evaluating StyleGAN2 CC and DDPM CB-AE.

Results

1. Concept Steerability or Intervention Success Rate

• Our CB-AE and CC improves steerability across GANs (+31%) and diffusion models (+28%) over the prior state-of-the-art method CBGM [1] while being 4-15x faster to train on average.

2. Interpreting generated images

• Our CB-AE (and CC) provide human-understandable concept predictions along with the generated images.

3. Concept intervention examples (CB-AE interventions)

• Concept intervention (modifying concepts) in the CB-AE leads to appropriate changes in the resulting image generation, enabling controllable generation.

4. Concept intervention examples (optimization-based interventions)

• Optimization-based interventions also enable controllable generation with improved orthogonality (i.e. less change in other concepts, closer to the original generation) than CB-AE interventions.

Sources

[1] CBGM (ICLR 2024): https://github.com/prescient-design/CBGM

[2] StyleGAN3 GitHub repo (it has StyleGAN2 pretrained weights for CelebA-HQ and CUB)

[3] CelebA-HQ pretrained DDPM repo

Cite this work

A. Kulkarni, G. Yan, C. Sun, T. Oikarinen, and T.-W. Weng, Interpretable Generative Models through Post-hoc Concept Bottlenecks, CVPR 2025

@inproceedings{kulkarni2025interpretable
    title={Interpretable Generative Models through Post-hoc Concept Bottlenecks},
    author={Kulkarni, Akshay and Yan, Ge and Sun, Chung-En and Oikarinen, Tuomas and Weng, Tsui-Wei},
    booktitle={IEEE/CVF Conference on Computer Vision and Pattern Recognition},
    year={2025},
}