225 research outputs found
A note on patch-based low-rank minimization for fast image denoising
Patch-based low-rank minimization for image processing attracts much
attention in recent years. The minimization of the matrix rank coupled with the
Frobenius norm data fidelity can be solved by the hard thresholding filter with
principle component analysis (PCA) or singular value decomposition (SVD). Based
on this idea, we propose a patch-based low-rank minimization method for image
denoising. The main denoising process is stated in three equivalent way: PCA,
SVD and low-rank minimization. Compared to recent patch-based sparse
representation methods, experiments demonstrate that the proposed method is
rather rapid, and it is effective for a variety of natural grayscale images and
color images, especially for texture parts in images. Further improvements of
this method are also given. In addition, due to the simplicity of this method,
we could provide an explanation of the choice of the threshold parameter,
estimation of PSNR values, and give other insights into this method.Comment: 4pages (two columns
An ELU Network with Total Variation for Image Denoising
In this paper, we propose a novel convolutional neural network (CNN) for
image denoising, which uses exponential linear unit (ELU) as the activation
function. We investigate the suitability by analyzing ELU's connection with
trainable nonlinear reaction diffusion model (TNRD) and residual denoising. On
the other hand, batch normalization (BN) is indispensable for residual
denoising and convergence purpose. However, direct stacking of BN and ELU
degrades the performance of CNN. To mitigate this issue, we design an
innovative combination of activation layer and normalization layer to exploit
and leverage the ELU network, and discuss the corresponding rationale.
Moreover, inspired by the fact that minimizing total variation (TV) can be
applied to image denoising, we propose a TV regularized L2 loss to evaluate the
training effect during the iterations. Finally, we conduct extensive
experiments, showing that our model outperforms some recent and popular
approaches on Gaussian denoising with specific or randomized noise levels for
both gray and color images.Comment: 10 pages, Accepted by the 24th International Conference on Neural
Information Processing (2017
Enhanced CNN for image denoising
Owing to flexible architectures of deep convolutional neural networks (CNNs),
CNNs are successfully used for image denoising. However, they suffer from the
following drawbacks: (i) deep network architecture is very difficult to train.
(ii) Deeper networks face the challenge of performance saturation. In this
study, the authors propose a novel method called enhanced convolutional neural
denoising network (ECNDNet). Specifically, they use residual learning and batch
normalisation techniques to address the problem of training difficulties and
accelerate the convergence of the network. In addition, dilated convolutions
are used in the proposed network to enlarge the context information and reduce
the computational cost. Extensive experiments demonstrate that the ECNDNet
outperforms the state-of-the-art methods for image denoising.Comment: CAAI Transactions on Intelligence Technology[J], 201
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