Method for detecting ship trail of ocean synthetic aperture radar image

Abstract

The invention relates to a method for detecting a ship trail of an ocean synthetic aperture radar image. The method comprises the following steps: firstly, identifying and removing an extraordinary area from the image; performing histogram equalization treatment; and lastly, performing Radon conversion and converting the image so as to convert a linear structure in the image into a peak / valley point of a conversion domain, thereby detecting and obtaining the features of the linear structure in the image. According to the method provided by the invention, the ultra-bright or ultra-dark extraordinary area is automatically identified and is removed when a valid data template is generated, and then the problem of uneven brightness of the whole image is further solved by adopting the self-adaptive histogram equalization, and lastly, the normalizing Radon conversion is utilized to convert the weak linear ship trail in the complex ocean SAR (Synthetic Aperture Radar) image into the obvious peak / valley point in a transformation space, so that the effectiveness of the detection for the ship trail is greatly increased.

Description

technical field [0001] The invention relates to the technical field of ship wake detection in marine synthetic aperture radar images, in particular to a ship wake detection method in marine synthetic aperture radar images (SAR), and is especially suitable for complex marine environments. Background technique [0002] Synthetic Aperture Radar (SAR) has all-weather and all-weather observation capabilities. It uses SAR images to detect and monitor maritime ship targets. It has been widely used in maritime transportation, coastal defense early warning, and military applications. All countries in the world attach great importance to the use of SAR to detect ship targets and their wakes. As early as 1986, scientists from the Norwegian National Defense Research Institute (NDRE) used SAR images obtained by SEASAT to carry out a research called "SAR detection of ships and ship wakes"; American scientist Lyden published the classification and generation of ship wakes in SAR images. M...

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Problems solved by technology

[0023] In fact, when carrying out large-scale monitoring, there will be obvious unevenness of light and shade in SAR images due to reasons such as large differences in seawater depth, concentration of plankton, or large changes in sea conditions.

Especially in some special cases of complex marine environments, the unevenness of light and shade in the image will be more serious. For example, in the seas with higher latitudes in the northern hemisphere in winter, there may be ice blocks or icebergs on the sea surface, which will appear as some deep in the SAR image. The dark area of ​​the imaging device itself may also produce a large number of invalid data areas in the image

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