Adaptive LiDAR Sampling and Depth Completion Using Ensemble Variance.

This work considers the problem of depth completion, with or without image data, where an algorithm may measure the depth of a prescribed limited number of pixels. The algorithmic challenge is to choose pixel positions strategically and dynamically to maximally reduce overall depth estimation error. This setting is realized in daytime or nighttime depth completion for autonomous vehicles with a programmable LiDAR.

Optoacoustic model-based inversion using anisotropic adaptive total-variation regularization.

In optoacoustic tomography, image reconstruction is often performed with incomplete or noisy data, leading to reconstruction errors. Significant improvement in reconstruction accuracy may be achieved in such cases by using nonlinear regularization schemes, such as total-variation minimization and -based sparsity-preserving schemes. In this paper, we introduce a new framework for optoacoustic image reconstruction based on adaptive anisotropic total-variation regularization, which is more capable of preserving complex boundaries than conventional total-variation regularization.

Spectral Total-Variation Local Scale Signatures for Image Manipulation and Fusion.

We propose a unified framework for isolating, comparing and differentiating objects within an image. We rely on the recently proposed total-variation transform, yielding a continuous, multi-scale, fully edge-preserving, local descriptor, referred to as spectral total-variation local scale signatures. We show and analyze several useful merits of this framework.

Blind Facial Image Quality Enhancement Using Non-Rigid Semantic Patches.

We propose a new way to solve a very general blind inverse problem of multiple simultaneous degradations, such as blur, resolution reduction, noise, and contrast changes, without explicitly estimating the degradation. The proposed concept is based on combining semantic non-rigid patches, problem-specific high-quality prior data, and non-rigid registration tools. We show how a significant quality enhancement can be achieved, both visually and quantitatively, in the case of facial images.

Separation Surfaces in the Spectral TV Domain for Texture Decomposition.

In this paper, we introduce a novel notion of separation surfaces for image decomposition. A surface is embedded in the spectral total-variation (TV) 3D domain and encodes a spatially varying separation scale. The method allows good separation of textures with gradually varying pattern size, pattern contrast, or illumination.

Nonlinear scale space with spatially varying stopping time.

A general scale space algorithm is presented for denoising signals and images with spatially varying dominant scales. The process is formulated as a partial differential equation with spatially varying time. The proposed adaptivity is semi-local and is in conjunction with the classical gradient-based diffusion coefficient, designed to preserve edges.

Forward-and-backward diffusion processes for adaptive image enhancement and denoising.

Signal and image enhancement is considered in the context of a new type of diffusion process that simultaneously enhances, sharpens, and denoises images. The nonlinear diffusion coefficient is locally adjusted according to image features such as edges, textures, and moments. As such, it can switch the diffusion process from a forward to a backward (inverse) mode according to a given set of criteria.

Variational denoising of partly textured images by spatially varying constraints.

Denoising algorithms based on gradient dependent regularizers, such as nonlinear diffusion processes and total variation denoising, modify images towards piecewise constant functions. Although edge sharpness and location is well preserved, important information, encoded in image features like textures or certain details, is often compromised in the process of denoising. We propose a mechanism that better preserves fine scale features in such denoising processes.

Estimation of optimal PDE-based denoising in the SNR sense.

This paper is concerned with finding the best partial differential equation-based denoising process, out of a set of possible ones. We focus on either finding the proper weight of the fidelity term in the energy minimization formulation or on determining the optimal stopping time of a nonlinear diffusion process. A necessary condition for achieving maximal SNR is stated, based on the covariance of the noise and the residual part.

Image enhancement and denoising by complex diffusion processes.

The linear and nonlinear scale spaces, generated by the inherently real-valued diffusion equation, are generalized to complex diffusion processes, by incorporating the free Schrödinger equation. A fundamental solution for the linear case of the complex diffusion equation is developed. Analysis of its behavior shows that the generalized diffusion process combines properties of both forward and inverse diffusion.