Contrast Reduction Research Articles

Pinhole shifting for reducing speckle contrast in reflectance confocal microscopy.

The high speckle contrast in reflectance confocal microscopy is perhaps the most limiting factor on this imaging modality, particularly in high scattering samples such as biological tissues. In this Letter, we propose and numerically analyze a method for speckle reduction that uses simple lateral shifting of the confocal pinhole in several directions, which results in reduced speckle contrast and only a moderate penalty in both lateral and axial resolutions. By simulating free-space electromagnetic wave propagation through a high-numerical-aperture (NA) confocal imaging system, and assuming only single-scattering events, we characterize the 3D point-spread function (PSF) that results from full-aperture pinhole shifting. Simple summation of four different pinhole-shifted images resulted in a 36% reduction in speckle contrast, with reductions of only 17% and 60% in the lateral and axial resolutions, respectively. This method could be particularly useful in noninvasive microscopy for clinical diagnosis, where fluorescence labeling is impractical and high image quality is imperative for achieving accurate diagnosis.

Cortical thickness in brain imaging studies using FreeSurfer and CAT12: A matter of reproducibility

A reproducibility crisis has been reported across many research fields, including neuroimaging, reaching up to 70% of studies. Neuroimaging data, such as magnetic resonance imaging (MRI), requires pre-processing to allow for inter-subject comparison, increase signal contrast and noise reduction. As manual MRI pre-processing is time consuming and requires expertise, multiple automatic pre-processing frameworks have been proposed. However, neuroimaging studies often report divergent results, even for similar populations, thus it is important to determine whether this occurs as a result of different processing tools. Two of the most used tools are FreeSurfer and the Computational Anatomy Toolbox (CAT12). In this study we assessed the reproducibility between these two automatic pre-processing frameworks for structural MRI and test-retest reliability within framework on estimation of cortical thickness. Our results show that the reproducibility between the frameworks is lower at the region-of-interest (ROI) level than at individual level. Furthermore, we found that the reproducibility was lower in paediatric samples than in adults. Finally, an acquisition site effect was also identified. Given the widespread use of these frameworks in basic and clinical neuroscience, the results of multicentric cross-sectional studies must be interpreted with caution, particularly with paediatric samples. The observed reproducibility issue might be one of the sources of discrepancies reported in neuroimaging studies. On a positive note, framework test-retest reliability within subject is high, suggesting that inconsistency of results may be less concerning in longitudinal studies. The code is available at: https://cibit-uc.github.io/fs-cat12-cortical-thickness-reproducibility.

High-pressure behavior of 3.65 Å phase: Insights from Raman spectroscopy

Abstract The 3.65 Å phase [MgSi(OH)6] is a hydrous phase that is predicted to be stable in a simplified MgO-SiO2-H2O (MSH) ternary system at pressures exceeding 9 GPa. Along cold subduction zones, it is likely to transport water, bound in its crystalline lattice, into the Earth’s interior. The 3.65 Å phase consists of Mg and Si octahedral sites attached to the hydroxyl group that forms a hydrogen bond and is predicted to undergo pressure-induced symmetrization of the hydrogen bond. Therefore, in this study, we investigate the high-pressure behavior of the 3.65 Å phase using Raman spectroscopy. We have conducted five distinct compressions up to ~60 GPa using two different pressure-transmitting media—alcohol mixture and neon. At ambient conditions, we identified vibrational modes using complementary first-principles simulations based on density functional perturbation theory. Upon compression, we note that the first derivative of the vibrational modes in the lattice region stiffens, i.e., b1lattice > 0. In contrast, the hydroxyl region softens, i.e., b1OH > 0. This is indicative of the strengthening of hydrogen bonding upon compression. We noticed a significant broadening of vibrational modes related to hydroxyl groups that are indicative of proton disorder. However, within the maximum pressures explored in this study, we did not find evidence for pressure-induced symmetrization of the hydrogen bonds. We used the pressure derivative of the vibrational modes to determine the ratio of the bulk moduli and their pressure derivative. We note that the smaller bulk moduli of hydrous phases compared to the major mantle phases are compensated by significantly larger pressure derivatives of the bulk moduli for the hydrous phases. This leads to a significant reduction in the elasticity contrast between hydrous and major mantle phases. Consequently, the detection of the degree of mantle hydration is likely to be challenging at greater depths.

Automatic defogging, deblurring, and real-time segmentation system for sewer pipeline defects

Conventional deep-learning-based inspection methods for sewer pipeline defects neglect the complex inner environment of pipelines (e.g., fog and motion blur) and real-time segmentation despite their high accuracy for clear images. To solve the problem of low accuracy and slow speed of fuzzy image inspection, a novel defogging, deblurring, and real-time segmentation system for sewer pipeline defects is proposed. First, an attention-based algorithm for defogging and a generative adversarial network (GAN) for deblurring are created to improve the sharpness of pipeline images. Second, a real-time segmentation network called Pipe-Yolact-Edge is proposed to detect the defects in pipeline images at a pixel level, which achieves the highest mean average precision (mAP) of 92.65% and the fastest speed of 41.23 frames per second (fps) among the state-of-the-art segmentation networks. Comparison experiments show that the mAP of the proposed segmentation model is improved by 7.93% and 15.43% after defogging and deblurring of pipeline images, respectively, thus revealing the impact of Pipe-Defog-Net and Pipe-Deblur-GAN. In particular, the proposed defogging and deblurring methods for pipeline images can reduce the effects of contrast reduction, boundary enlargement, and missing inspection of small defects caused by fog and motion blur. Finally, the trained model is transferred into a small development device to segment the images of pipeline defects on site.

New phase diagram of miscible viscous fingering instabilities in porous media with dead-end pores

Classical miscible viscous fingering (VF) instability occurs when a less viscous fluid displaces a more viscous one in porous media with pores that are all well connected. Here, we investigate numerically how non-negligible dead-end pores, together with a limited mass transfer rate Da between the two pore types, affect fingering dynamics. We identify a new stabilizing mechanism induced by a reduction of effective viscosity contrast at an intermediate Da, which leads to a new phase diagram for VF instabilities in a Péclet number—Pe–Da parameter space and an elimination of fingers and tip-splitting at low and large values of Pe, respectively. A scaling analysis, along with an analysis of interfacial lengths, accurately predicts the boundary of the flow regimes and explains the origin of the new stabilizing mechanism.

Underwater enhancement based on a self-learning strategy and attention mechanism for high-intensity regions

Images acquired during underwater activities suffer from environmental properties of the water, such as turbidity and light attenuation. These phenomena cause color distortion, blurring, and contrast reduction. In addition, irregular ambient light distribution causes color channel unbalance and regions with high-intensity pixels. Recent works related to underwater image enhancement, and based on deep learning approaches, tackle the lack of paired datasets generating synthetic ground-truth. In this paper, we present a self-supervised learning methodology for underwater image enhancement based on deep learning that requires no paired datasets. The proposed method estimates the degradation present in underwater images. Besides, an autoencoder reconstructs this image, and its output image is degraded using the estimated degradation information. Therefore, the strategy replaces the output image with the degraded version in the loss function during the training phase. This procedure misleads the neural network that learns to compensate the additional degradation. As a result, the reconstructed image is an enhanced version of the input image. Also, the algorithm presents an attention module to reduce high-intensity areas generated in enhanced images by color channel unbalances and outlier regions. Furthermore, the proposed methodology requires no ground-truth. Besides, only real underwater images were used to train the neural network, and the results indicate the effectiveness of the method in terms of color preservation, color cast reduction, and contrast improvement.

Probability Distribution of Extreme Events in a Baroclinic Wave Laboratory Experiment

Atmospheric westerly jet streams are driven by temperature differences between low and high latitudes and the rotation of the Earth. Meandering jet streams and propagating Rossby waves are responsible for the variable weather in the mid-latitudes. Moreover, extreme weather events such as heat waves and cold spells are part of the jet stream dynamics. For many years, a simple analog in the form of a simplified laboratory experiment, the differentially heated rotating annulus, has provided insight into the dynamics of the meandering jet stream. In the present study, probability density distributions of extreme events from a long-term laboratory experiment are studied and compared to the atmospheric probability density distributions. Empirical distributions of extreme value monthly block data are derived for the experimental and atmospheric cases. Generalized extreme value distributions are adjusted to the empirical distributions, and the distribution parameters are compared. Good agreement was found, but the distributions of the experimental data showed a shift toward larger extreme values, and some explanations for this shift are suggested. The results indicate that the laboratory model might be a useful tool for investigating changes in extreme event distributions due to climate change. In the laboratory context, the change can be modeled by an increase in total temperature accompanied by a reduction in the radial heat contrast.

Evaluation of capacity of power hammer machine foundation from high strain dynamic load test: Field test and axisymmetric numerical modeling

The power hammer machines induce harmful vibrations in different parts of the foundation which may result in excessive dynamic settlement. While designing the hammer machine foundation, variety of static and repetitive impact load tests are generally conducted to ensure both the stability and serviceability of the foundation system. The static load test (SLT) is performed in the case of such foundations to obtain the ultimate capacity. However, the SLT is unable to predict the reliable response of the machine foundation. Hence, the current study is aimed to investigate the static and dynamic resistance of power hammer machine foundation by employing the high strain dynamic load test (DLT). The test procedure involves measuring the acceleration, axial force and settlement at the top of the machine foundation. Additionally, the soil resistance pertaining to damping is assumed to disappear with the zero-velocity at the first moment, which is identical to the unloading point method (UPM). Also, the field test and axisymmetric finite element analysis by considering the nonlinear soil model were performed to evaluate the stress settlement curve (SSC) from both SLT and DLT. The results reveal that the capacity of the machine foundation subjected to repetitive dynamic loads increases gradually and then tend to remain stable in case of additional impact loads. The SLTs showed 3–4 % higher static resistance than the first DLT and 8–9 % reduction in contrast to the second DLT. Moreover, the residual plastic deformation of the soil beneath the machine foundation was recorded to rapidly increase at the beginning of hammer tamping while it decreased steadily with further increasing of the hammer blows.

Measuring Indirect Radiation-Induced Perfusion Change in Fed Vasculature Using Dynamic Contrast CT.

Recent functional lung imaging studies have presented evidence of an “indirect effect” on perfusion damage, where regions that are unirradiated or lowly irradiated but that are supplied by highly irradiated regions observe perfusion damage post-radiation therapy (RT). The purpose of this work was to investigate this effect using a contrast-enhanced dynamic CT protocol to measure perfusion change in five novel swine subjects. A cohort of five Wisconsin Miniature Swine (WMS) were given a research course of 60 Gy in five fractions delivered locally to a vessel in the lung using an Accuray Radixact tomotherapy system with Synchrony motion tracking to increase delivery accuracy. Imaging was performed prior to delivering RT and 3 months post-RT to yield a 28–36 frame image series showing contrast flowing in and out of the vasculature. Using MIM software, contours were placed in six vessels on each animal to yield a contrast flow curve for each vessel. The contours were placed as follows: one at the point of max dose, one low-irradiated (5–20 Gy) branching from the max dose vessel, one low-irradiated (5–20 Gy) not branching from the max dose vessel, one unirradiated (<5 Gy) branching from the max dose vessel, one unirradiated (<5 Gy) not branching from the max dose vessel, and one in the contralateral lung. Seven measurements (baseline-to-baseline time and difference, slope up and down, max rise and value, and area under the curve) were acquired for each vessel’s contrast flow curve in each subject. Paired Student t-tests showed statistically significant (p < 0.05) reductions in the area under the curve in the max dose, and both fed contours indicating an overall reduction in contrast in these regions. Additionally, there were statistically significant reductions observed when comparing pre- and post-RT in slope up and down in the max dose, low-dose fed, and no-dose fed contours but not the low-dose not-fed, no-dose not-fed, or contralateral contours. These findings suggest an indirect damage effect where irradiation of the vasculature causes a reduction in perfusion in irradiated regions as well as regions fed by the irradiated vasculature.

Comparison of Breast Cancer Radiotherapy Techniques Regarding Secondary Cancer Risk and Normal Tissue Complication Probability - Modelling and Measurements Using a 3D-Printed Phantom.

BackgroundRadiotherapy after breast-conserving therapy is a standard postoperative treatment of breast cancer, which can be carried out with a variety of irradiation techniques. The treatment planning must take into consideration detrimental effects on the neighbouring organs at risk—the lung, the heart, and the contralateral breast, which can include both short- and long-term effects represented by the normal tissue complication probability and secondary cancer risk.Patients and MethodsIn this planning study, we investigate intensity-modulated (IMRT) and three-dimensional conformal (3D-CRT) radiotherapy techniques including sequential or simultaneously integrated boosts as well as interstitial multicatheter brachytherapy boost techniques of 38 patients with breast-conserving surgery retrospectively. We furthermore develop a 3D-printed breast phantom add-on to allow for catheter placement and to measure the out-of-field dose using thermoluminescent dosimeters placed inside an anthropomorphic phantom. Finally, we estimate normal tissue complication probabilities using the Lyman–Kutcher–Burman model and secondary cancer risks using the linear non-threshold model (out-of-field) and the model by Schneider et al. (in-field).ResultsThe results depend on the combination of primary whole-breast irradiation and boost technique. The normal tissue complication probabilities for various endpoints are of the following order: 1%–2% (symptomatic pneumonitis, ipsilateral lung), 2%–3% (symptomatic pneumonitis, whole lung), and 1%–2% (radiation pneumonitis grade ≥ 2, whole lung). The additional relative risk of ischemic heart disease ranges from +25% to +35%. In-field secondary cancer risk of the ipsilateral lung in left-sided treatment is around 50 per 10,000 person-years for 20 years after exposure at age 55. Out-of-field estimation of secondary cancer risk results in approximately 5 per 10,000 person-years each for the contralateral lung and breast.ConclusionsIn general, 3D-CRT shows the best risk reduction in contrast to IMRT. Regarding the boost concepts, brachytherapy is the most effective method in order to minimise normal tissue complication probability and secondary cancer risk compared to teletherapy boost concepts. Hence, the 3D-CRT technique in combination with an interstitial multicatheter brachytherapy boost is most suitable in terms of risk avoidance for treating breast cancer with techniques including boost concepts.

Nanodroplet-Mediated Low-Energy Mechanical Ultrasound Surgery.

Mechanical ultrasound surgery methods use short, high-intensity pulses to fractionate tissues. This study reports the development of a two-step technology for low-energy mechanical ultrasound surgery of tissues using nanodroplets to reduce the pressure threshold. Step 1 consists of vaporizing the nanodroplets into gaseous microbubbles via megahertz ultrasound excitation. Then, low-frequency ultrasound is applied to the microbubbles, which turns them into therapeutic warheads that trigger potent mechanical effects in the surrounding tissue. The use of nanoscale nanodroplets coupled with low-frequency ultrasound reduces the pressure threshold required for mechanical ultrasound surgery by an order of magnitude. In addition, their average diameter of 300 nm can overcome challenges associated with the size of microbubbles. Optimization experiments were performed to determine the ultrasound parameters for nanodroplet vaporization and the subsequent microbubble implosion processes. Optimal vaporization was obtained when transmitting a 2-cycle excitation pulse at a center frequency of 5 MHz and a peak negative pressure of 4.1 MPa (mechanical index=1.8). Low-frequency insonation of the generated microbubbles at a center frequency of 850, 250 or 80 kHz caused enhanced contrast reduction at a center frequency of 80 kHz, compared with the other frequencies, while operating at the same mechanical index of 0.9. Nanodroplet-mediated insonation of ex vivo chicken liver samples generated mechanical damage. Low-frequency treatment at a mechanical index of 0.9 and a center frequency of 80 kHz induced the largest lesion area (average of 0.59 mm2) compared with 250- and 850-kHz treatments with the same mechanical index (average lesions areas of 0.29 and 0.19 mm2, respectively, p < 0.001). The two-step approach makes it possible to conduct both the vaporization and implosion stages at mechanical indices below 1.9, thus avoiding undesired mechanical damage. The findings indicate that coupled with low-frequency ultrasound, nanodroplets can be used for low-energy mechanical ultrasound surgery.

Spectral interference contrast based non-contact photoacoustic microscopy realized by SDOCT.

We introduce a method to extract the photoacoustic (PA) signal from a contrast reduction of the interference spectrum acquired by spectral domain optical coherence tomography (SDOCT). This all-optical detection is achieved in a noncontact manner directly on the water surface covered on the sample by using its specular reflection. During SDOCT exposure, the phase of the interference spectrum keeps shaking according to the water surface vibration induced by PA excitation. This results in an interference contrast reduction which is quantified by a fast Fourier transform (FFT) for PA imaging. A tungsten filament, asparagus fern leaf, and mouse auricle are imaged to demonstrate the method.

Bessel-beam illumination Raman microscopy.

We demonstrate the use of Bessel beams for side illumination slit-scanning Raman imaging for label-free and hyperspectral analysis of cell spheroids. The background elimination by the side illumination and the aberration-resistant Bessel beam drastically improves the image contrast in Raman observation, allowing label-free investigation of intracellular molecules in thick biological samples. Live cell spheroids were observed to confirm the improvement in image contrast and background reduction with Bessel illumination compared to conventional epi-line illumination.

Adaptive infrared and visible image fusion method by using rolling guidance filter and saliency detection

Infrared and visible images have good complementarity; thus, infrared and visible image fusion methods are extensively used in military, target detection, pattern recognition, and other applications. However, problems such as halo effect, poor background texture, and contrast reduction are encountered in image fusion methods. In addition, when the visible image is disturbed by smoke and high brightness, it will affect the quality of the fused image, making image fusion a challenge. To address these problems, an adaptive image fusion method is proposed in this paper. First, the image decomposition method based on rolling guidance filter and saliency detection (RGFSD) is proposed. Next, the source image is decomposed into three layers by using RGFSD: detail layer, salient layer, and base layer. The detail layer is then fused using the phase congruency strategy. Subsequently, the local entropy and gradient (LEG) method is proposed to simulate the perception of significant information by the human visual system to assign the weights for salient layer fusion. Next, the base layer is fused using the averaging method. Furthermore, an image enhancement method based on rolling guidance filter and contrast-limited adaptive histogram equalization is proposed to enhance the detail and contrast of the fused image. Finally, the proposed method is compared qualitatively and quantitatively with eight fusion methods. The experiment results show that compared with the existing methods, the proposed method can better enhance the contrast and retain details of the source images.

Foveal and peripheral visual quality and accommodation with multifocal contact lenses.

Multifocal contact lenses are increasingly popular interventions for controlling myopia. This study presents the short-term effects of multifocal contact lenses on foveal and peripheral vision. The MiSight contact lenses designed to inhibit myopia progression and the 1-Day Acuvue Moist contact lenses designed for presbyopia were investigated. The MiSight produced similar foveal results to spectacles despite the increased astigmatism and coma. The MiSight also reduced the low-contrast resolution acuity in the periphery, despite no clear change in relative peripheral refraction. When compared with spectacles, Acuvue Moist decreased accommodative response and reduced foveal high- and low-contrast resolution acuity, whereas peripheral thresholds were more similar to those of spectacles. The most likely treatment property for myopia control by the MiSight is the contrast reduction in the peripheral visual field and the changed accommodation.

Methicillin-resistant Staphylococcus aureus enterocolitis in a 16-month-old boy: a case report

BackgroundMethicillin-resistant Staphylococcus aureus enterocolitis is a rare disease that typically affects immunocompromised adults. Most cases of pediatric enterocolitis are caused by Gram-negative bacteria, Gram-positive Clostridiodes difficile, or viruses. This is the first published case report of a toddler with methicillin-resistant Staphylococcus aureus enterocolitis.Case presentationA 16-month-old non-Hispanic White boy with no past medical or psychosocial history initially presented to the emergency room with abdominal pain and emesis. Past family history was pertinent only for his father having a history of constipation. He was diagnosed with intussusception and underwent successful contrast reduction on hospital day 0. The following day, the patient had recurrent symptoms and a repeat contrast enema showed no evidence of recurrent intussusception. A computed tomography scan was obtained, which was concerning for possible recurrence with compromised bowel. He was taken to the operating room for operative reduction and underwent an ileocecetomy with primary handsewn end-to-end anastomosis. His postoperative course was complicated by an anastomotic leak on hospital day 6 necessitating reoperation and creation of an end ileostomy with mucous fistula. He received intravenous metronidazole, ceftriaxone, and ceftazidime antibiotics during his hospital course. On postoperative day 12, the patient developed a sudden increase in ileostomy output, and stool cultures were obtained. His symptoms persisted despite diet modifications, stopping antibiotics, and initiating loperamide. Three days later, stool cultures resulted negative for Escherichia coli, Salmonella, Shigella, Campylobacter species, and Clostridiodes difficile but were positive for methicillin-resistant Staphylococcus aureus. The patient was started on a 10-day course of oral vancomycin and discharged home in good condition 4 days later. After 12 weeks, the patient underwent reversal of the ostomy and is doing well at the 1 month postoperative follow-up, now 5 months from his initial surgery.ConclusionsTo our knowledge, this is the first published report of a toddler being diagnosed with methicillin-resistant Staphylococcus aureus enterocolitis. Because methicillin-resistant Staphylococcus aureus enterocolitis is rare and has overlapping symptoms with more common gastrointestinal pathologies, it is often misdiagnosed. When a patient presents with diarrhea or high ostomy output along with fecal cultures negative for Clostridiodes difficile and other common pathogenic agents, methicillin-resistant Staphylococcus aureus should be considered.

Accurate mechanical-optical theoretical model of cross-axis sensitivity of an interferometric micro-optomechanical accelerometer.

An interferometric micro-optomechanical accelerometer usually has ultrahigh sensitivity and accuracy. However, cross-axis interference inevitably degrades the performance, including its detection accuracy and output signal contrast. To accurately clarify the influence of cross-axis interference, a modified mechanical-optical theoretical model is established. The rotation of the proof mass and the detected light intensity are quantitatively investigated with a load of cross-axis acceleration. A simulation and experiment are performed to verify the correctness of the theoretical model when the cross-axis acceleration is from 0 to 0.175 g. The results demonstrate that this model has a more than fivefold accuracy increase compared with conventional theoretical models when the cross-axis acceleration is from 0.06 to 0.175 g. In addition, we provide a suppression method to diminish the rotation of the proof mass based on squeeze film air damping, which significantly suppresses the contrast reduction caused by cross-axis interference.

Speckle free efficient light engine for high power laser projectors and automobile headlamps

Laser speckles and spurious fringes are the major obstacles in the development of emerging technologies relating to laser-based projection imaging and illumination. It becomes more challenging when such systems employ high-power lasers, such as laser-based cinema projectors or laser-based automobile headlamps. Addressing such challenges, we report a compact design and step-by-step development scheme of a laser speckle reduction system in this article. The method comprises a metallic ball-mirror connected with the mechanically dynamic and thermally conductive heat sink. The ball-mirror was highly reflecting and coated with a transparent thick film of ZnO nanoparticle embedded epoxy adhesive that provides volume scattering of a highly directional laser beam. Epoxy layer were further diffused by sandblasting to achieve surface scattering of the laser light. The combined effect of volume and surface scattering were utilized to produce spatial diversity, while the temporal diversity was achieved by the rotation of ball-mirror diffuser system. Spatial and temporal diversities are the fundamental speckle reduction techniques that become more efficient when they are employed with a tiny pyramidal reflective cavity. TracePro simulations demonstrate the efficiency enhancement in the system due to the involvement of a pyramidal reflector for three primary wavelengths (RGB). Qualitative results of the light-scattering for red, green, and blue lasers and the quantitative results of speckle contrast are reported. Speckle contrast reduction was experimentally achieved by 0.0248 for red, 0.0298 for green, and 0.0213 for blue laser diodes.

Plug-and-play adaptive optics for two photon high-speed volumetric imaging

To understand brain functions, it is important to study functional connectivity among stereoscopically distributed neurons. Since the brain is composed of 3D neuron networks, volumetric imaging with high spatiotemporal resolution is highly desirable. Two-photon microscopy (2PM) conveniently offers 3D tissue imaging with sub-micrometer resolution based on its intrinsic optical sectioning and deep penetration capabilities. However, the main challenge lies in the volumetric imaging speed and contrast reduction in deep tissue due to aberration. In this study, we integrate a tunable acoustic gradient lens and a plug-and-play adaptive-optics lens into 2PM. The former provides ∼100 kHz axial scan rate, achieving volumetric imaging rate in 1–10 Hz range, while the latter enhances image contrast by nearly two-fold in deep brain regions via correcting both systematic and sample aberrations. The combination offers a practical approach toward high-speed, high-contrast optical volumetric imaging of brain tissues.

Underwater Image Restoration via Information Distribution and Light Scattering Prior

Underwater images suffer from blurred details, color cast, and contrast reduction, caused by absorption and scattering of light. To address these degradation issues, we propose a novel underwater image restoration method based on information distribution and light scattering prior. Concretely, we first estimate the background light according to the information distribution and light scattering characteristics of the background light area. Then, the scene depth map and transmission map are obtained by the relationship between the brightness information and color attenuation. Finally, the underwater image formation model is inversed to obtain the restored image. Extensive experiments indicate that our method can effectively remove the color cast and increase contrast. Furthermore, compared with several state-of-the-art methods, the proposed method yields better results. The qualitative and quantitative results demonstrate that our approach is superior to other comparison methods.