A method and system for grayscale equalization of side-scan sonar images

Abstract

The invention discloses a side-scan sonar image gray level equalization method and system. The method comprises: geocoding the track line data and the side-scan sonar waterfall image to obtain a side-scan sonar image; dividing each side-scan sonar line image with geographical coordinates in the side-scan sonar image into multiple path buffers area; the pixels located in the same path buffer are on the same side of the track line, and the distance from the track line is within the preset range; the grayscale features of each path buffer are extracted, and the path buffers are buffered according to the grayscale features Gray level equalization is performed on the pixels in the area; gap interpolation and image mosaic are performed on all equalized side-scan sonar survey line images with geographic coordinates to obtain equalized side-scan sonar images. The invention performs gray level equalization processing on the side-scan sonar image after geocoding, which can improve the image quality of the side-scan sonar, and further improve the accuracy of subsequent image interpretation or automatic classification.

Description

technical field [0001] The invention relates to the technical field of underwater geomorphology measurement, in particular to a method and system for equalizing gray levels of side-scan sonar images. Background technique [0002] Side Scan Sonar (SSS), also known as "Side Scan Sonar", is a geophysical survey technology that realizes submarine landform imaging. The side-scan sonar emits a beam fan to the seabed through oblique incidence, and performs seabed imaging by recording the arrival time and intensity of the echo signal. [0003] The side-scan sonar transducer continuously emits acoustic signals and records the received acoustic signals in time sequence, and displays the received signal corresponding to each emission as a row of pixels according to a specific color mapping rule, which is called a "scan line". As the side-scan sonar moves along the course, these pixels are arranged row by row, and the resulting image is called a "waterfall image." like figure 1 As sh...

AI Technical Summary

Problems solved by technology

The gain correction method at the signal level is based on the physical model of sound wave propagation in water, which is the basis for gray level equalization correction, but the image forming effect is often difficult to meet expectations; the gray histogram normalization method at the waterfall level is based on a continuous measurement signal. Statistical features. Compared with the first method, this method has a certain improvement in the mapping effect, but because each pixel of the waterfall image does not directly contain spatial coordinate information, it is only suitable for grayscale correction of local images. The side-scan sonar Image quality still needs to be improved

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