522 research outputs found
Progressive Feature Fusion Network for Realistic Image Dehazing
Single image dehazing is a challenging ill-posed restoration problem. Various
prior-based and learning-based methods have been proposed. Most of them follow
a classic atmospheric scattering model which is an elegant simplified physical
model based on the assumption of single-scattering and homogeneous atmospheric
medium. The formulation of haze in realistic environment is more complicated.
In this paper, we propose to take its essential mechanism as "black box", and
focus on learning an input-adaptive trainable end-to-end dehazing model. An
U-Net like encoder-decoder deep network via progressive feature fusions has
been proposed to directly learn highly nonlinear transformation function from
observed hazy image to haze-free ground-truth. The proposed network is
evaluated on two public image dehazing benchmarks. The experiments demonstrate
that it can achieve superior performance when compared with popular
state-of-the-art methods. With efficient GPU memory usage, it can
satisfactorily recover ultra high definition hazed image up to 4K resolution,
which is unaffordable by many deep learning based dehazing algorithms.Comment: 14 pages, 7 figures, 1 tables, accepted by ACCV201
CGGAN: A Context Guided Generative Adversarial Network For Single Image Dehazing
Image haze removal is highly desired for the application of computer vision.
This paper proposes a novel Context Guided Generative Adversarial Network
(CGGAN) for single image dehazing. Of which, an novel new encoder-decoder is
employed as the generator. And it consists of a feature-extraction-net, a
context-extractionnet, and a fusion-net in sequence. The feature extraction-net
acts as a encoder, and is used for extracting haze features. The
context-extraction net is a multi-scale parallel pyramid decoder, and is used
for extracting the deep features of the encoder and generating coarse dehazing
image. The fusion-net is a decoder, and is used for obtaining the final
haze-free image. To obtain more better results, multi-scale information
obtained during the decoding process of the context extraction decoder is used
for guiding the fusion decoder. By introducing an extra coarse decoder to the
original encoder-decoder, the CGGAN can make better use of the deep feature
information extracted by the encoder. To ensure our CGGAN work effectively for
different haze scenarios, different loss functions are employed for the two
decoders. Experiments results show the advantage and the effectiveness of our
proposed CGGAN, evidential improvements over existing state-of-the-art methods
are obtained.Comment: 12 pages, 7 figures, 3 table
Fractional Multiscale Fusion-based De-hazing
This report presents the results of a proposed multi-scale fusion-based
single image de-hazing algorithm, which can also be used for underwater image
enhancement. Furthermore, the algorithm was designed for very fast operation
and minimal run-time. The proposed scheme is the faster than existing
algorithms for both de-hazing and underwater image enhancement and amenable to
digital hardware implementation. Results indicate mostly consistent and good
results for both categories of images when compared with other algorithms from
the literature.Comment: 23 pages, 13 figures, 2 table
Dense Haze: A benchmark for image dehazing with dense-haze and haze-free images
Single image dehazing is an ill-posed problem that has recently drawn
important attention. Despite the significant increase in interest shown for
dehazing over the past few years, the validation of the dehazing methods
remains largely unsatisfactory, due to the lack of pairs of real hazy and
corresponding haze-free reference images. To address this limitation, we
introduce Dense-Haze - a novel dehazing dataset. Characterized by dense and
homogeneous hazy scenes, Dense-Haze contains 33 pairs of real hazy and
corresponding haze-free images of various outdoor scenes. The hazy scenes have
been recorded by introducing real haze, generated by professional haze
machines. The hazy and haze-free corresponding scenes contain the same visual
content captured under the same illumination parameters. Dense-Haze dataset
aims to push significantly the state-of-the-art in single-image dehazing by
promoting robust methods for real and various hazy scenes. We also provide a
comprehensive qualitative and quantitative evaluation of state-of-the-art
single image dehazing techniques based on the Dense-Haze dataset. Not
surprisingly, our study reveals that the existing dehazing techniques perform
poorly for dense homogeneous hazy scenes and that there is still much room for
improvement.Comment: 5 pages, 2 figure
O-HAZE: a dehazing benchmark with real hazy and haze-free outdoor images
Haze removal or dehazing is a challenging ill-posed problem that has drawn a
significant attention in the last few years. Despite this growing interest, the
scientific community is still lacking a reference dataset to evaluate
objectively and quantitatively the performance of proposed dehazing methods.
The few datasets that are currently considered, both for assessment and
training of learning-based dehazing techniques, exclusively rely on synthetic
hazy images. To address this limitation, we introduce the first outdoor scenes
database (named O-HAZE) composed of pairs of real hazy and corresponding
haze-free images. In practice, hazy images have been captured in presence of
real haze, generated by professional haze machines, and OHAZE contains 45
different outdoor scenes depicting the same visual content recorded in
haze-free and hazy conditions, under the same illumination parameters. To
illustrate its usefulness, O-HAZE is used to compare a representative set of
state-of-the-art dehazing techniques, using traditional image quality metrics
such as PSNR, SSIM and CIEDE2000. This reveals the limitations of current
techniques, and questions some of their underlying assumptions.Comment: arXiv admin note: text overlap with arXiv:1804.0509
Real-world Underwater Enhancement: Challenges, Benchmarks, and Solutions
Underwater image enhancement is such an important low-level vision task with
many applications that numerous algorithms have been proposed in recent years.
These algorithms developed upon various assumptions demonstrate successes from
various aspects using different data sets and different metrics. In this work,
we setup an undersea image capturing system, and construct a large-scale
Real-world Underwater Image Enhancement (RUIE) data set divided into three
subsets. The three subsets target at three challenging aspects for enhancement,
i.e., image visibility quality, color casts, and higher-level
detection/classification, respectively. We conduct extensive and systematic
experiments on RUIE to evaluate the effectiveness and limitations of various
algorithms to enhance visibility and correct color casts on images with
hierarchical categories of degradation. Moreover, underwater image enhancement
in practice usually serves as a preprocessing step for mid-level and high-level
vision tasks. We thus exploit the object detection performance on enhanced
images as a brand new task-specific evaluation criterion. The findings from
these evaluations not only confirm what is commonly believed, but also suggest
promising solutions and new directions for visibility enhancement, color
correction, and object detection on real-world underwater images.Comment: arXiv admin note: text overlap with arXiv:1712.04143 by other author
Single Image Dehazing through Improved Atmospheric Light Estimation
Image contrast enhancement for outdoor vision is important for smart car
auxiliary transport systems. The video frames captured in poor weather
conditions are often characterized by poor visibility. Most image dehazing
algorithms consider to use a hard threshold assumptions or user input to
estimate atmospheric light. However, the brightest pixels sometimes are objects
such as car lights or streetlights, especially for smart car auxiliary
transport systems. Simply using a hard threshold may cause a wrong estimation.
In this paper, we propose a single optimized image dehazing method that
estimates atmospheric light efficiently and removes haze through the estimation
of a semi-globally adaptive filter. The enhanced images are characterized with
little noise and good exposure in dark regions. The textures and edges of the
processed images are also enhanced significantly.Comment: Multimedia Tools and Applications (2015
Gated Fusion Network for Single Image Dehazing
In this paper, we propose an efficient algorithm to directly restore a clear
image from a hazy input. The proposed algorithm hinges on an end-to-end
trainable neural network that consists of an encoder and a decoder. The encoder
is exploited to capture the context of the derived input images, while the
decoder is employed to estimate the contribution of each input to the final
dehazed result using the learned representations attributed to the encoder. The
constructed network adopts a novel fusion-based strategy which derives three
inputs from an original hazy image by applying White Balance (WB), Contrast
Enhancing (CE), and Gamma Correction (GC). We compute pixel-wise confidence
maps based on the appearance differences between these different inputs to
blend the information of the derived inputs and preserve the regions with
pleasant visibility. The final dehazed image is yielded by gating the important
features of the derived inputs. To train the network, we introduce a
multi-scale approach such that the halo artifacts can be avoided. Extensive
experimental results on both synthetic and real-world images demonstrate that
the proposed algorithm performs favorably against the state-of-the-art
algorithms
NTIRE 2020 Challenge on NonHomogeneous Dehazing
This paper reviews the NTIRE 2020 Challenge on NonHomogeneous Dehazing of
images (restoration of rich details in hazy image). We focus on the proposed
solutions and their results evaluated on NH-Haze, a novel dataset consisting of
55 pairs of real haze free and nonhomogeneous hazy images recorded outdoor.
NH-Haze is the first realistic nonhomogeneous haze dataset that provides ground
truth images. The nonhomogeneous haze has been produced using a professional
haze generator that imitates the real conditions of haze scenes. 168
participants registered in the challenge and 27 teams competed in the final
testing phase. The proposed solutions gauge the state-of-the-art in image
dehazing.Comment: CVPR Workshops Proceedings 202
Input Dropout for Spatially Aligned Modalities
Computer vision datasets containing multiple modalities such as color, depth,
and thermal properties are now commonly accessible and useful for solving a
wide array of challenging tasks. However, deploying multi-sensor heads is not
possible in many scenarios. As such many practical solutions tend to be based
on simpler sensors, mostly for cost, simplicity and robustness considerations.
In this work, we propose a training methodology to take advantage of these
additional modalities available in datasets, even if they are not available at
test time. By assuming that the modalities have a strong spatial correlation,
we propose Input Dropout, a simple technique that consists in stochastic hiding
of one or many input modalities at training time, while using only the
canonical (e.g. RGB) modalities at test time. We demonstrate that Input Dropout
trivially combines with existing deep convolutional architectures, and improves
their performance on a wide range of computer vision tasks such as dehazing,
6-DOF object tracking, pedestrian detection and object classification.Comment: Accepted in ICIP 2020. Personal use of this material is permitted.
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