119 research outputs found
Fast Two-step Blind Optical Aberration Correction
The optics of any camera degrades the sharpness of photographs, which is a
key visual quality criterion. This degradation is characterized by the
point-spread function (PSF), which depends on the wavelengths of light and is
variable across the imaging field. In this paper, we propose a two-step scheme
to correct optical aberrations in a single raw or JPEG image, i.e., without any
prior information on the camera or lens. First, we estimate local Gaussian blur
kernels for overlapping patches and sharpen them with a non-blind deblurring
technique. Based on the measurements of the PSFs of dozens of lenses, these
blur kernels are modeled as RGB Gaussians defined by seven parameters. Second,
we remove the remaining lateral chromatic aberrations (not contemplated in the
first step) with a convolutional neural network, trained to minimize the
red/green and blue/green residual images. Experiments on both synthetic and
real images show that the combination of these two stages yields a fast
state-of-the-art blind optical aberration compensation technique that competes
with commercial non-blind algorithms.Comment: 28 pages, 20 figures, accepted at ECCV'22 as a poste
Convolutional Deblurring for Natural Imaging
In this paper, we propose a novel design of image deblurring in the form of
one-shot convolution filtering that can directly convolve with naturally
blurred images for restoration. The problem of optical blurring is a common
disadvantage to many imaging applications that suffer from optical
imperfections. Despite numerous deconvolution methods that blindly estimate
blurring in either inclusive or exclusive forms, they are practically
challenging due to high computational cost and low image reconstruction
quality. Both conditions of high accuracy and high speed are prerequisites for
high-throughput imaging platforms in digital archiving. In such platforms,
deblurring is required after image acquisition before being stored, previewed,
or processed for high-level interpretation. Therefore, on-the-fly correction of
such images is important to avoid possible time delays, mitigate computational
expenses, and increase image perception quality. We bridge this gap by
synthesizing a deconvolution kernel as a linear combination of Finite Impulse
Response (FIR) even-derivative filters that can be directly convolved with
blurry input images to boost the frequency fall-off of the Point Spread
Function (PSF) associated with the optical blur. We employ a Gaussian low-pass
filter to decouple the image denoising problem for image edge deblurring.
Furthermore, we propose a blind approach to estimate the PSF statistics for two
Gaussian and Laplacian models that are common in many imaging pipelines.
Thorough experiments are designed to test and validate the efficiency of the
proposed method using 2054 naturally blurred images across six imaging
applications and seven state-of-the-art deconvolution methods.Comment: 15 pages, for publication in IEEE Transaction Image Processin
Joint deconvolution and demosaicing
International audienceWe present a new method to jointly perform deblurring and color- demosaicing of RGB images. Our method is derived following an inverse problem approach in a MAP framework. To avoid noise am- plification and allow for interpolation of missing data, we make use of edge-preserving spatial regularization and spectral regularization. We demonstrate the improvements brought by our algorithm by processing both simulated and real RGB images obtained with a Bayer's color filter and with different types of blurring
Learning to Jointly Deblur, Demosaick and Denoise Raw Images
We address the problem of non-blind deblurring and demosaicking of noisy raw images. We adapt an existing learningbased approach to RGB image deblurring to handle raw images by introducing a new interpretable module that jointly demosaicks and deblurs them. We train this model on RGB images converted into raw ones following a realistic invertible camera pipeline. We demonstrate the effectiveness of this model over two-stage approaches stacking demosaicking and deblurring modules on quantitive benchmarks. We also apply our approach to remove a camera's inherent blur (its colordependent point-spread function) from real images, in essence deblurring sharp images
A convex formulation for hyperspectral image superresolution via subspace-based regularization
Hyperspectral remote sensing images (HSIs) usually have high spectral
resolution and low spatial resolution. Conversely, multispectral images (MSIs)
usually have low spectral and high spatial resolutions. The problem of
inferring images which combine the high spectral and high spatial resolutions
of HSIs and MSIs, respectively, is a data fusion problem that has been the
focus of recent active research due to the increasing availability of HSIs and
MSIs retrieved from the same geographical area.
We formulate this problem as the minimization of a convex objective function
containing two quadratic data-fitting terms and an edge-preserving regularizer.
The data-fitting terms account for blur, different resolutions, and additive
noise. The regularizer, a form of vector Total Variation, promotes
piecewise-smooth solutions with discontinuities aligned across the
hyperspectral bands.
The downsampling operator accounting for the different spatial resolutions,
the non-quadratic and non-smooth nature of the regularizer, and the very large
size of the HSI to be estimated lead to a hard optimization problem. We deal
with these difficulties by exploiting the fact that HSIs generally "live" in a
low-dimensional subspace and by tailoring the Split Augmented Lagrangian
Shrinkage Algorithm (SALSA), which is an instance of the Alternating Direction
Method of Multipliers (ADMM), to this optimization problem, by means of a
convenient variable splitting. The spatial blur and the spectral linear
operators linked, respectively, with the HSI and MSI acquisition processes are
also estimated, and we obtain an effective algorithm that outperforms the
state-of-the-art, as illustrated in a series of experiments with simulated and
real-life data.Comment: IEEE Trans. Geosci. Remote Sens., to be publishe
Super-Resolution for Imagery from Integrated Microgrid Polarimeters
Imagery from microgrid polarimeters is obtained by using a mosaic of pixel-wise micropolarizers on a focal plane array (FPA). Each distinct polarization image is obtained by subsampling the full FPA image. Thus, the effective pixel pitch for each polarization channel is increased and the sampling frequency is decreased. As a result, aliasing artifacts from such undersampling can corrupt the true polarization content of the scene. Here we present the first multi-channel multi-frame super-resolution (SR) algorithms designed specifically for the problem of image restoration in microgrid polarization imagers. These SR algorithms can be used to address aliasing and other degradations, without sacrificing field of view or compromising optical resolution with an anti-aliasing filter. The new SR methods are designed to exploit correlation between the polarimetric channels. One of the new SR algorithms uses a form of regularized least squares and has an iterative solution. The other is based on the faster adaptive Wiener filter SR method. We demonstrate that the new multi-channel SR algorithms are capable of providing significant enhancement of polarimetric imagery and that they outperform their independent channel counterparts
Depth Restoration in Under-Display Time-of-Flight Imaging
Under-display imaging has recently received considerable attention in both academia and industry. As a variation of this technique, under-display ToF (UD-ToF) cameras enable depth sensing for full-screen devices. However, it also brings problems of image blurring, signal-to-noise ratio and ranging accuracy reduction. To address these issues, we propose a cascaded deep network to improve the quality of UD-ToF depth maps. The network comprises two subnets, with the first using a complex-valued network in raw domain to perform denoising, deblurring and raw measurements enhancement jointly, while the second refining depth maps in depth domain based on the proposed multi-scale depth enhancement block (MSDEB). To enable training, we establish a data acquisition device and construct a real UD-ToF dataset by collecting real paired ToF raw data. Besides, we also build a large-scale synthetic UD-ToF dataset through noise analysis. The quantitative and qualitative evaluation results on public datasets and ours demonstrate that the presented network outperforms state-of-the-art algorithms and can further promote full-screen devices in practical applications
Computational Imaging Approach to Recovery of Target Coordinates Using Orbital Sensor Data
This dissertation addresses the components necessary for simulation of an image-based recovery of the position of a target using orbital image sensors. Each component is considered in detail, focusing on the effect that design choices and system parameters have on the accuracy of the position estimate. Changes in sensor resolution, varying amounts of blur, differences in image noise level, selection of algorithms used for each component, and lag introduced by excessive processing time all contribute to the accuracy of the result regarding recovery of target coordinates using orbital sensor data.
Using physical targets and sensors in this scenario would be cost-prohibitive in the exploratory setting posed, therefore a simulated target path is generated using Bezier curves which approximate representative paths followed by the targets of interest. Orbital trajectories for the sensors are designed on an elliptical model representative of the motion of physical orbital sensors. Images from each sensor are simulated based on the position and orientation of the sensor, the position of the target, and the imaging parameters selected for the experiment (resolution, noise level, blur level, etc.). Post-processing of the simulated imagery seeks to reduce noise and blur and increase resolution. The only information available for calculating the target position by a fully implemented system are the sensor position and orientation vectors and the images from each sensor. From these data we develop a reliable method of recovering the target position and analyze the impact on near-realtime processing. We also discuss the influence of adjustments to system components on overall capabilities and address the potential system size, weight, and power requirements from realistic implementation approaches
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