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Spatially Adaptive Computation Time for Residual Networks

This code implements a deep learning architecture based on Residual Network that dynamically adjusts the number of executed layers for the regions of the image. The architecture is end-to-end trainable, deterministic and problem-agnostic. The included code applies this to the CIFAR-10 an ImageNet image classification problems. It is implemented using TensorFlow and TF-Slim.

Paper describing the project:

Michael Figurnov, Maxwell D. Collins, Yukun Zhu, Li Zhang, Jonathan Huang, Dmitry Vetrov, Ruslan Salakhutdinov. Spatially Adaptive Computation Time for Residual Networks. CVPR 2017 [arxiv].

Image (with detections)	Ponder cost map

Setup

Install prerequisites:

pip install -r requirements.txt  # CPU
pip install -r requirements-gpu.txt  # GPU

Prerequisite packages:

• Python 2.x/3.x (mostly tested with Python 2.7)
• Tensorflow 1.0
• NumPy
• (Optional) nose
• (Optional) h5py
• (Optional) matplotlib

Run tests. It takes a couple of minutes:

nosetests --logging-level=WARNING

CIFAR-10

Download and convert CIFAR-10 dataset:

PYTHONPATH=external python external/download_and_convert_cifar10.py --dataset_dir="${HOME}/tensorflow/data/cifar10"

Let's train and continuously evaluate a CIFAR-10 Adaptive Computation Time model with five residual units per block (ResNet-32):

export ACT_LOGDIR='/tmp/cifar10_resnet_5_act_1e-2'
python cifar_main.py --model_type=act --model=5 --tau=0.01 --train_log_dir="${ACT_LOGDIR}/train" --save_summaries_secs=300 &
python cifar_main.py --model_type=act --model=5 --tau=0.01 --checkpoint_dir="${ACT_LOGDIR}/train" --eval_dir="${ACT_LOGDIR}/eval" --mode=eval

Or, for spatially adaptive computation time (SACT):

export SACT_LOGDIR='/tmp/cifar10_resnet_5_sact_1e-2'
python cifar_main.py --model_type=sact --model=5 --tau=0.01 --train_log_dir="${SACT_LOGDIR}/train" --save_summaries_secs=300 &
python cifar_main.py --model_type=sact --model=5 --tau=0.01 --checkpoint_dir="${SACT_LOGDIR}/train" --eval_dir="${SACT_LOGDIR}/eval" --mode=eval

To download and evaluate a pretrained ResNet-32 SACT model (1.8 MB file):

mkdir -p models && curl https://s3.us-east-2.amazonaws.com/sact-models/cifar10_resnet_5_sact_1e-2.tar.gz | tar xv -C models
python cifar_main.py --model_type=sact --model=5 --tau=0.01 --checkpoint_dir='models/cifar10_resnet_5_sact_1e-2' --mode=eval --eval_dir='/tmp' --evaluate_once

This model is expected to achieve an accuracy of 91.82%, with the output looking like so:

eval/Accuracy[0.9182]
eval/Mean Loss[0.59591407]
Total Flops/mean[82393168]
Total Flops/std[7588926]
...

ImageNet

Follow the instructions to prepare the ImageNet dataset in TF-Slim format. The default directory for the dataset is ~/tensorflow/imagenet. You can change it with the --dataset_dir flag.

We initialized all ACT/SACT models with a pretrained ResNet-101 model (159MB file).

Download pretrained ResNet-101 SACT model, trained with tau=0.005 (160 MB file):

mkdir -p models && curl https://s3.us-east-2.amazonaws.com/sact-models/imagenet_101_sact_5e-3.tar.gz | tar xv -C models

Evaluate the pretrained model

python imagenet_eval.py --model_type=sact --model=101 --tau=0.005 --checkpoint_dir=models/imagenet_101_sact_5e-3 --eval_dir=/tmp --evaluate_once

Expected output:

eval/Accuracy[0.75609803]
eval/Recall@5[0.9274632117722329]
Total Flops/mean[1.1100941e+10]
Total Flops/std[4.5691142e+08]
...

Note that evaluation on the full validation dataset will take some time using only CPU. Add the arguments --num_examples=10 --batch_size=10 for a quicker test.

Draw some images from ImageNet validation set and the corresponding ponder cost maps:

python imagenet_export.py --model_type=sact --model=101 --tau=0.005 --checkpoint_dir=models/imagenet_101_sact_5e-3 --export_path=/tmp/maps.h5 --batch_size=1 --num_examples=200

mkdir /tmp/maps
python draw_ponder_maps.py --input_file=/tmp/maps.h5 --output_dir=/tmp/maps

Example visualizations. See Figure 9 of the paper for more

Image	Ponder cost map

Apply the pretrained model to your own jpeg images. For best results, first resize them to somewhere between 320x240 and 640x480.

python2 imagenet_ponder_map.py --model=101 --checkpoint_dir=models/imagenet_101_sact_5e-3 --images_pattern=pics/gasworks.jpg --output_dir output/

Image	Ponder cost map	Colorbar

Note that an ImageNet-pretrained model tends to ignore people - there is no "person" class in ImageNet!

Disclaimer

This is not an official Google product.