Underwater image enhancement method combining frequency domain and spatial domain

An underwater image and airspace technology, which is applied in the field of underwater image enhancement combining frequency domain and airspace, can solve the problem of reduced processing effect and achieve high contrast effect

Active Publication Date: 2019-12-03
HARBIN ENG UNIV
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However, this method can only perform offline image processing, and

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  • Underwater image enhancement method combining frequency domain and spatial domain
  • Underwater image enhancement method combining frequency domain and spatial domain
  • Underwater image enhancement method combining frequency domain and spatial domain

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[0039] The invention discloses an underwater image enhancement method combining frequency domain and air domain, belongs to the field of digital image processing, and is suitable for underwater visual synchronous positioning and an image preprocessing method before map building. This method first converts the read color image into a grayscale image; calculates the degree of blurring of the image, so as to adaptively select the degree of denoising in the frequency domain and the degree of contrast enhancement in the spatial domain; transforms the grayscale image into Frequency space: Divide the image in frequency space into illumination component and reflection component, and use the transfer function to perform additive denoising on illumination and reflection components after logarithmic transformation; inversely transform the frequency domain image to obtain the image in the space domain; Segmentation, count the gray-level probability density function of each sub-image block;...

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Abstract

The invention discloses an underwater image enhancement method combining a frequency domain and a spatial domain, and belongs to the field of underwater digital image processing. The method comprisesthe following steps: reading an underwater color image, and converting the underwater color image into a grayscale image; adaptively selecting the denoising degree of a frequency domain and the contrast enhancement degree of a spatial domain; converting the grayscale image into a frequency space by using Fourier transform; de-noising the image in the frequency space; inverse Fourier transform is performed on the denoised image, and the denoised image is converted to a spatial domain; segmenting the image of the spatial domain into a plurality of sub-image blocks, and calculating a gray probability density function of each sub-image block; redistributing the probability density function; and calculating the redistributed gray level of each pixel in the sub-image blocks to obtain a finally enhanced image. Compared with the prior art, the invention has the advantages that underwater noise interference can be well removed, image detail features are enriched, consumed time is short, and theinvention is suitable for underwater vision synchronous positioning and image preprocessing before mapping.

Description

technical field [0001] The invention belongs to the field of underwater digital image processing, and in particular relates to an underwater image enhancement method combining frequency domain and air domain. Background technique [0002] Autonomous Underwater Vehicle (AUV) is an indispensable tool for humans to explore and develop the ocean, but its high navigation cost limits its large-scale application. Simultaneous Localization and Mapping (SLAM) technology is a better choice for AUV. Due to the characteristics of low visual visibility and high image noise underwater, it is difficult to realize visual SLAM. Therefore, it is necessary to perform better image enhancement processing before visual SLAM to meet the requirements of navigation, mapping and real-time performance. [0003] At present, underwater image enhancement methods mainly focus on using deep learning networks to restore images. This type of method previously required a large number of samples and was time...

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Application Information

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IPC IPC(8): G06T5/00G06T5/40
CPCG06T5/002G06T5/007G06T5/40G06T2207/10004G06T2207/10024G06T2207/20056G06T2207/20076
Inventor 李晔徐硕丛正张强马腾凌宇顾华宇武皓微贡雨森
Owner HARBIN ENG UNIV
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