23,134 research outputs found
Solving Inverse Problems with Piecewise Linear Estimators: From Gaussian Mixture Models to Structured Sparsity
A general framework for solving image inverse problems is introduced in this
paper. The approach is based on Gaussian mixture models, estimated via a
computationally efficient MAP-EM algorithm. A dual mathematical interpretation
of the proposed framework with structured sparse estimation is described, which
shows that the resulting piecewise linear estimate stabilizes the estimation
when compared to traditional sparse inverse problem techniques. This
interpretation also suggests an effective dictionary motivated initialization
for the MAP-EM algorithm. We demonstrate that in a number of image inverse
problems, including inpainting, zooming, and deblurring, the same algorithm
produces either equal, often significantly better, or very small margin worse
results than the best published ones, at a lower computational cost.Comment: 30 page
Rethinking the Pipeline of Demosaicing, Denoising and Super-Resolution
Incomplete color sampling, noise degradation, and limited resolution are the
three key problems that are unavoidable in modern camera systems. Demosaicing
(DM), denoising (DN), and super-resolution (SR) are core components in a
digital image processing pipeline to overcome the three problems above,
respectively. Although each of these problems has been studied actively, the
mixture problem of DM, DN, and SR, which is a higher practical value, lacks
enough attention. Such a mixture problem is usually solved by a sequential
solution (applying each method independently in a fixed order: DM DN
SR), or is simply tackled by an end-to-end network without enough
analysis into interactions among tasks, resulting in an undesired performance
drop in the final image quality. In this paper, we rethink the mixture problem
from a holistic perspective and propose a new image processing pipeline: DN
SR DM. Extensive experiments show that simply modifying the usual
sequential solution by leveraging our proposed pipeline could enhance the image
quality by a large margin. We further adopt the proposed pipeline into an
end-to-end network, and present Trinity Enhancement Network (TENet).
Quantitative and qualitative experiments demonstrate the superiority of our
TENet to the state-of-the-art. Besides, we notice the literature lacks a full
color sampled dataset. To this end, we contribute a new high-quality full color
sampled real-world dataset, namely PixelShift200. Our experiments show the
benefit of the proposed PixelShift200 dataset for raw image processing.Comment: Code is available at: https://github.com/guochengqian/TENe
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