International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395 -0056
Volume: 04 Issue: 04 | Apr -2017
p-ISSN: 2395-0072
www.irjet.net
A REVIEW ON UNDERWATER IMAGE ENHANCEMENT TECHNIQUES K. Natarajan Assistant Professor, Department of Computer Science, AVC College(Autonomous), Mannampandal, Tamilnadu, India. ---------------------------------------------------------------------***--------------------------------------------------------------------2. LITERATURE SURVEY Abstract - Image enhancement is one of the
preprocessing step in various computer vision applications. It is the process of improving the quality of image without any information loss. Usually the images are affected by various facts. Especially in underwater imagery, the haze and hue variations are greatly affected. This paper discusses the issues in underwater images and compares the existing image enhancement techniques for underwater images.
Key Words: Underwater images, Enhancement, Contrast stretching, Histogram Equilization, Color correction
Various image enhancement techniques are proposed in the literature. Haze in underwater image is reduced by dark channel. Hue variations are minimized by wavelength compensation [4]. Underwater images have low perceivability, small divergence and lessening hues [5]. A new scheme for enhancing ocean optical images whereas light traveling in the water, lights are distorted based on the
1. INTRODUCTION
wavelength [6]. Improve the nature of underwater images
Underwater images are corrupted due to scatters
that has been debased due to various twists [7]. John Y.
and amalgamation, resulting in low contrast and color
Chiang and Ying - Ching Chen.[8] proposed an algorithm that
distortion. Captured underwater images suffer from poor
uses WCID which helps in efficiently restoring image color
visibility. It is hard to acquire visible agreeable images at
balance and remove haze. Naim and Isa[9] proposed a
long or short distances due to the absorptive and dispersion
method called pixel distribution shifting color correction
nature of sea water. Noises diminish the details that could
(PDSCC) for digital color image to correct the white
contain significant information. Thus, super-resolving
reference point and ensure that the white reference point is
underwater speckled images are important for ocean
achromatic.
observation. These images frequently suffer from color distortion and low contrast due to the propagated light reduction with distance from the camera, mainly resulting from absorption and scattering effects.
Rizzi et al.[10] proposed unsupervised digital image color equalization with simultaneous global and local effects. Schechner and Karpel[11,12] analyzed the physical effects of visibility degradation and devised an image recovery
Even though there are many image enhancing
algorithm based on several images taken through a polarizer
techniques developed, such as white balance, color
at different orientations. Trucco and Olmos-Antillon[13]
correction, histogram equalization, and fusion-based
proposed
methods [1], they are not based on a physical model
simplifies Jaffe[14] and McGlamery[15]. Shelda Mohan and
underwater, and thus are not applicable for underwater
T.R. Mahesh, 2013[16] has presented Particle Swarm
images with different physical properties. It is challenging to
Optimization (PSO) for tuning the enhancement parameter
restore underwater images because of the deviation of
of Contrast Limited Adaptive Histogram Equalization relied
physical properties. Light reduction underwater[2] leads to
on Local Contrast Modification (LCM).
different degrees of color change, depending on wavelength, dissolved
organic
compounds,
water
salinity,
and
concentration of phytoplankton [3]. Š 2017, IRJET
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a self-tuning image restoration filter that
ICM[17] and UCM[18] are the popular techniques that use the histogram modification technique to increase the quality of underwater image. ICM and UCM methods give
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