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Semi-supervised semantic segmentation using CutMix and Colour Augmentation

Implementations of our papers:

• Semi-supervised semantic segmentation needs strong, varied perturbations by Geoff French, Samuli Laine, Timo Aila, Michal Mackiewicz and Graham Finlayson
• Colour augmentation for improved semi-supervised semantic segmentation by Geoff French and Michal Mackiewicz

Licensed under MIT license.

Colour augmentation

Please see our new paper for a full discussion, but a summary of our findings can be found in our [colour augmentation](Colour augmentation.ipynb) Jupyter notebook.

Requirements

We provide an environment.yml file that can be used to re-create a conda environment that provides the required packages:

conda env create -f environment.yml

Then activate with:

conda activate cutmix_semisup_seg

(note: this will not install the library needed to use the PSPNet architecture; see below)

In general we need:

• Python >= 3.6
• PyTorch >= 1.4
• torchvision 0.5
• OpenCV
• Pillow
• Scikit-image
• Scikit-learn
• click
• tqdm
• Jupyter notebook for the notebooks
• numpy 1.18

Requirements for PSPNet

To use the PSPNet architecture (see Pyramid Scene Parsing Network by Zhao et al.), you will need to install the logits-from_models branch of https://github.com/Britefury/semantic-segmentation-pytorch:

pip install git+https://github.com/Britefury/semantic-segmentation-pytorch.git@logits-from-models

Datasets

You need to:

1. Download/acquire the datsets
2. Write the config file semantic_segmentation.cfg giving their paths
3. Convert them if necessary; the CamVid, Cityscapes and ISIC 2017 datasets must be converted to a ZIP-based format prior to use. You must run the provided conversion utilities to create these ZIP files.

Dataset preparation instructions can be found here.

Running the experiments

We provide four programs for running experiments:

• train_seg_semisup_mask_mt.py: mask driven consistency loss (the main experiment)
• train_seg_semisup_aug_mt.py: augmentation driven consistency loss; used to attempt to replicate the ISIC 2017 baselines of Li et al.
• train_seg_semisup_ict.py: Interpolation Consistency Training; a baseline for contrast with our main approach
• train_seg_semisup_vat_mt.py: Virtual Adversarial Training adapted for semantic segmentation

They can be configured via command line arguments that are described here.

Shell scripts

To replicate our results, we provide shell scripts to run our experiments.

Cityscapes

> sh run_cityscapes_experiments.sh <run> <split_rng_seed>

where <run> is the name of the run and <split_rng_seed> is an integer RNG seed used to select the supervised samples. Please see the comments at the top of run_cityscapes_experiments.sh for further explanation.

To re-create the 5 runs we used for our experiments:

> sh run_cityscapes_experiments.sh 01 12345
> sh run_cityscapes_experiments.sh 02 23456
> sh run_cityscapes_experiments.sh 03 34567
> sh run_cityscapes_experiments.sh 04 45678
> sh run_cityscapes_experiments.sh 05 56789

Pascal VOC 2012 (augmented)

> sh run_pascal_aug_experiments.sh <n_supervised> <n_supervised_txt>

where <n_supervised> is the number of supervised samples and <n_supervised_txt> is that number as text. Please see the comments at the top of run_pascal_aug_experiments.sh for further explanation.

We use the same data split as Mittal et al. It is stored in data/splits/pascal_aug/split_0.pkl that is included in the repo.

Pascal VOC 2012 (augmented) with DeepLab v3+

> sh run_pascal_aug_deeplab3plus_experiments.sh <n_supervised> <n_supervised_txt>

ISIC 2017 Segmentation

> sh run_isic2017_experiments.sh <run> <split_rng_seed>

where <run> is the name of the run and <split_rng_seed> is an integer RNG seed used to select the supervised samples. Please see the comments at the top of run_isic2017_experiments.sh for further explanation.

To re-create the 5 runs we used for our experiments:

> sh run_isic2017_experiments.sh 01 12345
> sh run_isic2017_experiments.sh 02 23456
> sh run_isic2017_experiments.sh 07 78901
> sh run_isic2017_experiments.sh 08 89012
> sh run_isic2017_experiments.sh 09 90123

In early experiments, we test 10 seeds and selected the middle 5 when ranked in terms of performance, hence the specific seed choice.

Exploring the input data distribution present in semantic segmentation problems

Cluster assumption

First we examine the input data distribution presented by semantic segmentation problems with a view to determining if the low density separation assumption holds, in the notebook Semantic segmentation input data distribution.ipynb This notebook also contains the code used to generate the images from Figure 1 in the paper.

Inter-class and intra-class variance

Secondly we examine the inter-class and intra-class distance (as a proxy for inter-class and intra-class variance) in the notebook Plot inter-class and intra-class distances from files.ipynb

Note that running the second notebook requires that you generate some data files using the intra_inter_class_patch_dist.py program.

Toy 2D experiments

The toy 2D experiments used to produce Figure 3 in the paper can be run using the toy2d_train.py program, which is documented here.

You can re-create the toy 2D experiments by running the run_toy2d_experiments.sh shell script:

> sh run_toy2d_experiments.sh <run>