-- The denoising synthesis module --

Usage:

Make sure that you are in the code/ folder when running commands. You may need to install the requirements: pip install -r requirements.txt

To train a new model: python main.py train --data_loc (DATA_LOC)

where DATA_LOC contains images (.jpg, .png, etc) to be used to train the model

To generate samples from a trained model do:
python main.py eval --figure_path (FIGURE_PATH)

where FIGURE_PATH is the desired path for the output images. you can also change the number of examples to generate and save using the --eval_examples argument

you can edit the config.yaml file to change a variety of hyperparamters including: model width, model depth, image size, training steps, learning rate, batch size, and others.

If you create a new config file, make sure to specify its location using the --yaml_loc argument

The code includes different variants of denoising-based models, including: DDPMs or denoising diffusion probabilistic models, DDIMs or denoising diffusion implicit models, and a Denoising Student. Both DDPMs and DDIMs are iterative, meaning they use many iterations to produce a sample. They both reverse a noise adding "diffusion process" that is defined by a sequence of beta values. The main difference is that a DDPM adds a decreasing amount of noise to the data at each step of generation, while a DDIM does not. As a result, the DDIM process is deterministic given the same input noise, while the DDPM is not. For more information on DDPMs and DDIMs see https://arxiv.org/abs/2006.11239 and https://arxiv.org/abs/2010.02502.

Finally, the Denoising Student is a model that learns the same noise-to-data mapping as a DDIM model, only in one step as opposed to multiple. To implement this, we sample noise vectors from a standard normal, then give these to our trained DDIM which results in images. We save the noise and its corresponding images and train a second neural network to produce the same image given the noise. This results in faster sampling speed, at a cost of image quality. For more information see https://arxiv.org/abs/2101.02388. If you want to only use a DDPM or DDIM, use the --no_stg2 argument and specify the appropriate model type in the config file.

In this repository we include an example model trained on the MNIST dataset, and the results obtained with it. You can also view the module at https://codeocean.com/capsule/9690943/tree/v1 .