Denoisers#

The deepinv.models.Denoiser base class describe denoisers that take a noisy image as input and return a denoised image. They can be used as a building block for plug-and-play restoration, for building unrolled architectures, for artifact removal networks, or as a standalone denoisers. All denoisers have a forward method that takes a noisy image and a noise level (which generally corresponds to the standard deviation of the noise) as input and returns a denoised image:

>>> import torch
>>> import deepinv as dinv
>>> denoiser = dinv.models.DRUNet()
>>> sigma = 0.1
>>> image = torch.ones(1, 3, 32, 32) * .5
>>> noisy_image =  image + torch.randn(1, 3, 32, 32) * sigma
>>> denoised_image = denoiser(noisy_image, sigma)

Note

Some denoisers (e.g., deepinv.models.DnCNN) do not use the information about the noise level. In this case, the noise level is ignored.

Deep denoisers#

We provide the following list of deep denoising architectures, which are based on CNN, Transformer or hybrid CNN-Transformer modules. See Pretrained Weights for more information on pretrained denoisers.

Table 5 Deep denoisers#
Model	Type	Tensor Size (C, H, W)	Pretrained Weights	Noise level aware
`deepinv.models.AutoEncoder`	Fully connected	Any	No	No
`deepinv.models.UNet`	CNN	Any C; H,W>8	No	No
`deepinv.models.DnCNN`	CNN	Any C, H, W	RGB, grayscale	No
`deepinv.models.DRUNet`	CNN-UNet	Any C; H,W>8	RGB, grayscale	Yes
`deepinv.models.GSDRUNet`	CNN-UNet	Any C; H,W>8	RGB, grayscale	Yes
`deepinv.models.SCUNet`	CNN-Transformer	Any C, H, W	No	No
`deepinv.models.SwinIR`	CNN-Transformer	Any C, H, W	RGB	No
`deepinv.models.DiffUNet`	Transformer	Any C; H,W = 64, 128, 256, …	RGB	Yes
`deepinv.models.Restormer`	CNN-Transformer	Any C, H, W	RGB, grayscale, deraining, deblurring	No
`deepinv.models.ICNN`	CNN	Any C; H, W = 128, 256,…	No	No

Classical denoisers#

All denoisers in this list are non-learned (except for EPLL) and rely on hand-crafted priors.

Table 6 Non-Learned Denoisers Overview#
Model	Info	Tensor Size (C, H, W)
`deepinv.models.BM3D`	Patch-based denoiser	C=1 or C=3, any H, W.
`deepinv.models.MedianFilter`	Non-learned filter	Any C, H, W
`deepinv.models.TVDenoiser`	`Total variation prior`	Any C, H, W
`deepinv.models.TGVDenoiser`	Total generalized variation prior	Any C, H, W
`deepinv.models.WaveletDenoiser`	`Sparsity in orthogonal wavelet domain`	Any C, H, W
`deepinv.models.WaveletDictDenoiser`	Sparsity in overcomplete wavelet domain	Any C, H, W
`deepinv.models.EPLLDenoiser`	Learned patch-prior	C=1 or C=3, any H, W

Denoisers Utilities#

Equivariant denoisers#

Denoisers can be turned into equivariant denoisers by wrapping them with the deepinv.models.EquivariantDenoiser class, which symmetrizes the denoiser with respect to a transform from our available transforms such as deepinv.transform.Rotate or deepinv.transform.Reflect. You retain full flexibility by passing in the transform of choice. The denoising can either be averaged over the entire group of transformation (making the denoiser equivariant) or performed on 1 or n transformations sampled uniformly at random in the group, making the denoiser a Monte-Carlo estimator of the exact equivariant denoiser.

Complex denoisers#

Most denoisers in the library are designed to process real images. However, some problems, e.g., phase retrieval, require processing complex-valued images. The function deepinv.models.complex.to_complex_denoiser can convert any real-valued denoiser into a complex-valued denoiser. It can be simply called by complex_denoiser = to_complex_denoiser(denoiser).

Dynamic networks#

When using time-varying (i.e. dynamic) data of 5D shape (B,C,T,H,W), the reconstruction network must be adapted using deepinv.models.TimeAveragingNet.

To adapt any existing network to take dynamic data as independent time-slices, deepinv.models.TimeAgnosticNet creates a time-agnostic wrapper that flattens the time dimension into the batch dimension.