On the way to solve lighting problems in underwater imaging

García, Rafael; Nicosevici, Tudor; Cufí, Xavier

doi:10.1109/oceans.2002.1192107

Cited by 98 publications

(61 citation statements)

References 13 publications

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“…The use of imaging devices with special optical filters or polarizers in front of the lens (Schechner and Averbuch, 2007) can attenuate part of the incoming radiation and often alter the real colors of the scene to be acquired. Moreover, the use of artificial light sources can introduce more non-uniformities in the lighting of the scene (Garcia et al, 2002). Many imaging techniques have been proposed in the literature for this task (Schettini and Corchs, 2010), based on a physical model of the image formation process (image restoration techniques) or qualitative, subjective criteria to produce a more realistic image (image enhancement methods).…”

Section: Introductionmentioning

confidence: 99%

A New Color Correction Method for Underwater Imaging

Bianco

Muzzupappa

Bruno

et al. 2015

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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ABSTRACT:Recovering correct or at least realistic colors of underwater scenes is a very challenging issue for imaging techniques, since illumination conditions in a refractive and turbid medium as the sea are seriously altered. The need to correct colors of underwater images or videos is an important task required in all image-based applications like 3D imaging, navigation, documentation, etc. Many imaging enhancement methods have been proposed in literature for these purposes. The advantage of these methods is that they do not require the knowledge of the medium physical parameters while some image adjustments can be performed manually (as histogram stretching) or automatically by algorithms based on some criteria as suggested from computational color constancy methods. One of the most popular criterion is based on gray-world hypothesis, which assumes that the average of the captured image should be gray. An interesting application of this assumption is performed in the Ruderman opponent color space lαβ, used in a previous work for hue correction of images captured under colored light sources, which allows to separate the luminance component of the scene from its chromatic components. In this work, we present the first proposal for color correction of underwater images by using lαβ color space. In particular, the chromatic components are changed moving their distributions around the white point (white balancing) and histogram cutoff and stretching of the luminance component is performed to improve image contrast. The experimental results demonstrate the effectiveness of this method under gray-world assumption and supposing uniform illumination of the scene. Moreover, due to its low computational cost it is suitable for real-time implementation.

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Section: Introductionmentioning

confidence: 99%

A New Color Correction Method for Underwater Imaging

Bianco

Muzzupappa

Bruno

et al. 2015

Int. Arch. Photogramm. Remote Sens. Spatial Inf. Sci.

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“…An illumination compensation function [37] can be applied to the original images in order to correct this phenomenon, as can be seen in Fig. 5.…”

Section: Comparative Resultsmentioning

confidence: 99%

Challenges of close-range underwater optical mapping

Prados¹,

García²,

Escartı́n³

et al. 2011

OCEANS 2011 IEEE - Spain

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Abstract-Underwater optical mapping often involves the use of image mosaicing techniques. High quality mosaicing requires the application of blending methods to achieve continuous and artifact-free mosaics. Image blending has a dilated history of over three decades in the terrestrial and aerial fields. Unfortunately, the nature of the underwater medium adds additional difficulties to the mosaicing and blending tasks. In this paper a survey of the blending methods is given, focusing the attention on its applicability to underwater mosaicing. Image acquisition is performed by Autonomous Underwater Vehicles (AUVs) or Remotely Operated Vehicles (ROVs) in the deep ocean, a medium with aggressive light absorption and disrupting scattering effects that requires of the use of artificial lighting. A comprehensive comparison of the basic features and limitations of some of the most important existing blending techniques is presented. The goal is the generation of seamless and visually pleasant large area photo-mosaics of the seafloor, free from double contouring, ghosting and other disturbing and common blending artifacts.

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“…Furthermore linear stretching from 'S' value can provide stronger values to each range by looking at the less output values. Here a percentage of the saturating image can be controlled in order to perform better visual displays [15].…”

Section: Fig 4 Methodology For Underwater Image Enhancement Methodsmentioning

confidence: 99%

Underwater Image Enhancement Techniques: A Review

Madhumatke¹

2017

IJRASET

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Underwater images mainly suffer from the problem of poor color contrast and poor visibility. These problems occurred due to the scattering of light and refraction of light while entering from rarer to denser medium. Scattering causes the blurring of light and reduces the color contrast. These effects of water on underwater images are only not due the nature water but also because of the organisms and other material present in the water. Image enhancement is the process of improving the quality of the input image so that it would be easily understood by viewers in the future. Image enhancement improves the information content of the image and alters the visual impact of the image on the observer. Image enhancement intensifies the features of images. It accentuates the image features like edges, contrast to build display of photographs more useful for examination and study. Active range of the chosen features of images is amplified by enhancement so that they can be detected simply. Many techniques and methods are established by researchers to solve the problem of underwater image enhancement. In this work different underwater image enhancing techniques have been studied. Keywords: Homomorphic Filtering, Histogram Equalization, Bilateral filtering, Contrast Stretching, CLAHE I. INTRODUCTIONFrom last few years, underwater image processing area has received a great attention of researchers to explore the mysterious underwater world. Underwater surveys have numerous scientific applications in the field of archaeology, geology and biology, involving tasks such as ancient shipwreck prospection, environmental damage assessment etc. To capture a clear underwater image has a crucial importance in oceanic engineering [1]. Clear underwater images have a great importance in scientific operations like taking a census of sea population, include the discovery of objects in liquids or the image analysis needed to identify targets submerged in a liquid. There have also been studied that attempted to identify targets suspended in a solution. These studies could be useful for defense applications. For capturing a clear visible underwater image, water must be a limpid or clear, but naturally all the water is turbid with particles such as sand, planktonsor , minerals. As outdoor images are distorted because of particles present in the air, like that underwater images also get distorted because of particles present in the water. Underwater Images becomes more and more hazy or less visible as water depth increases. Generally underwater images get distorted because of two reasons. One is light scattering effect and second is color change effect. Therefore, the processing of underwater image captured is necessary because the quality of underwater images affect and these image leads due to low contrast, poor visibility conditions (absorption of natural light), non uniform lighting and little color variations, pepper noise and blur effect in the underwater images because of all these reasons number of methods are existing to cure...

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On the way to solve lighting problems in underwater imaging

Cited by 98 publications

References 13 publications

A New Color Correction Method for Underwater Imaging

A New Color Correction Method for Underwater Imaging

Challenges of close-range underwater optical mapping

Underwater Image Enhancement Techniques: A Review

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