294 research outputs found
Understanding Kernel Size in Blind Deconvolution
Most blind deconvolution methods usually pre-define a large kernel size to
guarantee the support domain. Blur kernel estimation error is likely to be
introduced, yielding severe artifacts in deblurring results. In this paper, we
first theoretically and experimentally analyze the mechanism to estimation
error in oversized kernel, and show that it holds even on blurry images without
noises. Then to suppress this adverse effect, we propose a low rank-based
regularization on blur kernel to exploit the structural information in degraded
kernels, by which larger-kernel effect can be effectively suppressed. And we
propose an efficient optimization algorithm to solve it. Experimental results
on benchmark datasets show that the proposed method is comparable with the
state-of-the-arts by accordingly setting proper kernel size, and performs much
better in handling larger-size kernels quantitatively and qualitatively. The
deblurring results on real-world blurry images further validate the
effectiveness of the proposed method.Comment: Accepted by WACV 201
Learning Discriminative Shrinkage Deep Networks for Image Deconvolution
Most existing methods usually formulate the non-blind deconvolution problem
into a maximum-a-posteriori framework and address it by manually designing
kinds of regularization terms and data terms of the latent clear images.
However, explicitly designing these two terms is quite challenging and usually
leads to complex optimization problems which are difficult to solve. In this
paper, we propose an effective non-blind deconvolution approach by learning
discriminative shrinkage functions to implicitly model these terms. In contrast
to most existing methods that use deep convolutional neural networks (CNNs) or
radial basis functions to simply learn the regularization term, we formulate
both the data term and regularization term and split the deconvolution model
into data-related and regularization-related sub-problems according to the
alternating direction method of multipliers. We explore the properties of the
Maxout function and develop a deep CNN model with a Maxout layer to learn
discriminative shrinkage functions to directly approximate the solutions of
these two sub-problems. Moreover, given the fast-Fourier-transform-based image
restoration usually leads to ringing artifacts while conjugate-gradient-based
approach is time-consuming, we develop the Conjugate Gradient Network to
restore the latent clear images effectively and efficiently. Experimental
results show that the proposed method performs favorably against the
state-of-the-art ones in terms of efficiency and accuracy
Learning Deep CNN Denoiser Prior for Image Restoration
Model-based optimization methods and discriminative learning methods have
been the two dominant strategies for solving various inverse problems in
low-level vision. Typically, those two kinds of methods have their respective
merits and drawbacks, e.g., model-based optimization methods are flexible for
handling different inverse problems but are usually time-consuming with
sophisticated priors for the purpose of good performance; in the meanwhile,
discriminative learning methods have fast testing speed but their application
range is greatly restricted by the specialized task. Recent works have revealed
that, with the aid of variable splitting techniques, denoiser prior can be
plugged in as a modular part of model-based optimization methods to solve other
inverse problems (e.g., deblurring). Such an integration induces considerable
advantage when the denoiser is obtained via discriminative learning. However,
the study of integration with fast discriminative denoiser prior is still
lacking. To this end, this paper aims to train a set of fast and effective CNN
(convolutional neural network) denoisers and integrate them into model-based
optimization method to solve other inverse problems. Experimental results
demonstrate that the learned set of denoisers not only achieve promising
Gaussian denoising results but also can be used as prior to deliver good
performance for various low-level vision applications.Comment: Accepted to CVPR 2017. Code: https://github.com/cszn/ircn
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