Dark-channel-prior-method-based non-uniform-light-field underwater target detection image enhancement method

Abstract

The invention discloses a dark-channel-prior-method-based non-uniform-light-field underwater target detection image enhancement method. The method comprises: an original color image of a non-uniform-light-field underwater detection target is obtained, and a corresponding transmission graph is calculated by using a minimum value filter algorithm; the original color image is converted into an original gray-scale image and the original image is divided into a bright region, a normal region, and a dark region; illumination vectors of all regions are calculated; with a guiding filter method, a guiding filter output image of the original color image is calculated on the condition of the transmission graph; recovered enhanced images of regions, with different brightness values, of the original image are calculated; and quantitative evaluation is carried out on a dodging processing recovered image in terms of a mean value, a variance, a contrast ratio, and an information entropy until the recovered enhanced image meets an index requirement. According to the invention, because of the guiding filter method with illumination vector weighting, smooth balancing processing is carried out on regions with different brightness values, so that the overall coordination of the processed image is enhanced and the texture information is enriched.

Description

technical field [0001] The invention belongs to the field of digital image information processing, and in particular relates to an image enhancement method for underwater target detection in a non-uniform light field based on a dark channel prior. Background technique [0002] The acquisition of underwater target detection images mainly relies on the surface texture information of close-range photographed objects, and there are special situations such as non-uniform illumination brightness, low signal-to-noise ratio, and low contrast. Due to the scattering and absorption of light by the water body, the use of auxiliary light sources will inevitably produce uneven lighting. Inhomogeneous illumination manifests as centering on the strongest point of the auxiliary light source and gradually weakening in the radial direction. There are three areas of brighter, normal, and darker illumination. There is a strong contrast between the brightness of the brighter area and the darker ...

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Problems solved by technology

Due to the influence of the optical characteristics of water and various particles, plankton and water flow in water, it is difficult to directly translate and transfer the research results of dark channel prior theory to enhance underwater detection images: 1. Because the whole image is only An illumination vector value is adopted, and the texture information is seriously lost for detection images in areas with large brightness deviations; second, the image enhancement process is an open-loop system, which does not have the ability to adaptively adjust the illumination vector value according to the image enhancement effect evaluation index parameters possibility of

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