A New Color Correction Method for Underwater Imaging

Abstract

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.

An Integrated Method to Remove Color Cast and Contrast Enhancement for Underwater Image

“…In some cases, after the removal of the color cast, color correction is applied [27]. In the underwater image enhancement method, Bianco et al [28] proposed a color correction method for underwater imaging in the Ruderman opponent color space lα β that based on GW and uniform illumination assumptions. Park et al [29] proposed an approach that able to adjust the color balance using biasness correction and the average luminance.…”

Guidelines for Underwater Image Enhancement Based on Benchmarking of Different Methods

“…Another method [16], which we refer to as LAB, is based on the assumptions of grey world and uniform illumination of the scene. The idea behind this method is to convert the input image from RGB to LAB space, correct colour casts of an image by adjusting the α and β components, increasing contrast by performing histogram cut-off and stretching and then convert the image back to the RGB space.…”

“…Bianco et al presented, in [16], the first proposal for the colour correction of underwater images by using lαβ colour space. A white balancing is performed by moving the distributions of the chromatic components (α, β) around the white point and the image contrast is improved through a histogram cut-off and stretching of the luminance (l) component.…”

Automatic Underwater Image Enhancement using Improved Dark Channel Prior

“…The default version neutralizes the midtones using a target color of sRGB 128 gray and clips the shadows and highlight pixels by 0.5%9. Auto Color is a common method for improving underwater images [Bianco et al 2015, Bruno et al 2015.…”

“…This is an ongoing process, but unfortunately no free tools for practical use are currently available. This might be the reason why many archaeologists use the automatic color correction of proprietary software like Photoshop 1 [Bianco et al 2015, Bruno et al 2015. The tool presented here, JEnhancer, is a candidate for closing this gap.…”