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Underwater image quality evaluating and measuring method based on power spectrum description

An underwater image and image quality technology, applied in image analysis, image data processing, instruments, etc., can solve the problems of noise, limited visual distance, poor visual consistency, etc.

Active Publication Date: 2014-03-05
HUAIHAI INST OF TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Most of the underwater images captured by the underwater image acquisition system have the following problems: limited viewing distance, low contrast, non-uniform illumination, blur, light spots, color loss and noise of various complex factors
The above methods are all aimed at the specific application of underwater image enhancement and restoration, and the image quality is only defined for the clarity of the image itself. In the subsequent processing based on the image quality, it will cause the target in the harsh underwater environment loss of image
There are currently no methods available for evaluating image quality in different aquatic environments
At the same time, the above methods will be affected by noise, and cannot be evaluated for untargeted underwater images and poorly consistent with visual subjectivity.

Method used

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  • Underwater image quality evaluating and measuring method based on power spectrum description

Examples

Experimental program
Comparison scheme
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Embodiment 1

[0080] Embodiment 1, a method for evaluating and measuring underwater image quality based on power spectrum description, for an underwater image I ,Assume I The image quality of PSVIQE={ C , Q},in, C As a factor describing the underwater imaging environment, Q is the measured value of the underwater image itself; C Used to distinguish the underwater environment where the underwater image is located, C The larger the value, the better the transparency of the water body, which is conducive to clear imaging. C The smaller the value, the greater the absorption and scattering attenuation of the water body; Q The value is a measure of the clarity of the underwater image; Q A larger value indicates that the image contains the target and is clearer. Q A smaller value indicates that there is no target in the underwater image or the image is blurred;

[0081] C ∈(0,1), C The value is determined by the following equation (1):

[0082] (1)

[0083] In formula...

Embodiment 2

[0098] Embodiment 2, experiment of underwater image quality evaluation measurement method based on power spectrum description:

[0099] refer to image 3 and 4 The average power spectrum in the log contrast direction of the pool image. In the pool image test, the pool is 4.5 meters long, 2 meters wide, and 2 meters high. Each test uses about 15 tons of water. There are four observation windows on three sides of the pool. The test targets are iron pipes and target boards, where the target board is a 40 cm × 50 cm white board, the stripe spacing on it is 2 mm, and the stripe widths are 1 mm, 2 mm, 3 mm, and 4 mm.

[0100] The power spectrum amplitude of the low-frequency part of the target image is larger, while the amplitude of the high-frequency part is smaller. In relatively turbid water bodies, due to the absorption and scattering of water, the image contrast is low and blurred. Therefore, the attenuation of the high frequency part in the image spectrum is more serious....

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Abstract

The invention provides an underwater image quality evaluating and measuring method based on power spectrum description. As for an underwater image I, the image quality of I is set as PSVIQE={C,Q}, wherein C is a factor describing underwater imaging environments, and Q is a quality measuring value of the underwater image; C is used for distinguishing the underwater environments where the underwater image is located, wherein the larger C is, the better water transparency is, clear imaging is facilitated, and the smaller C is, the higher absorption and scattering attenuation of water are; Q is used for measuring the clarity degree of the underwater image; if Q is larger, it is shown that the image comprises a target and is relatively clear, and if Q is smaller, it is shown that the underwater image does not comprise the target or is relatively blurred; an average block definition and image quality measuring method is adopted for Q, global contrast is selected in the method, quality measurement is conducted on the basis of partial definition, and a result of image edge detection is used as the basis for judging whether the target exists or not. The underwater image quality evaluating and measuring method is high in universality, combines imaging environment description and image quality measurement, and can be used for evaluating the value of the target image for observers in a severe imaging environment more effectively.

Description

technical field [0001] The invention belongs to the technical field of image processing and analysis, in particular to an underwater image quality evaluation and measurement method based on power spectrum description, which can process and analyze images taken in environments with absorption and scattering optical attenuation, such as underwater environments. Background technique [0002] The research of image quality objective evaluation algorithm is a very basic scientific problem in the field of image processing and image analysis. People hope to find a reliable and reasonable method for objective evaluation of image quality, which can approach the evaluation results of human visual system. In water, the speed of light is less affected by changes in temperature and salinity, the detection direction is good, and the positioning is more accurate. Target. Typical underwater visual images have serious non-uniform brightness and blurred details due to poor lighting condition...

Claims

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Application Information

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IPC IPC(8): G06T7/00
Inventor 杨淼
Owner HUAIHAI INST OF TECH
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