Brightness Compensation Method of SAR Single Scene Image Based on Local Histogram Compression

Abstract

The invention relates to an SAR single-scene image brightness compensating method based on local histogram compression. The method comprises the following steps of S1, for a to-be-processed SAR single-scene image, selecting an area with non-uniform brightness as a selected area; S2, performing traversal on the selected area, obtaining a lowest pixel gray scale value and a highest pixel gray scalevalue in the selected area; S3, drawing the histogram of the selected area, and selecting compression probability p of the histogram, obtaining the highest gray scale value x after compression of theselected area, wherein the gray scale range of the selected area is divided into two parts of [A,x] and [x+1,B]; S4, obtaining an appropriate compression factor mf through an iteration method so thatthe gray scale of the selected area is compressed from an initial range [A,B] to [A,x]; and S5, performing traversal on the selected area, for the gray scale value Ik of a random pixel, if Ik belongsto [A,x], outputting the Ik; and otherwise, outputting Ik / mf, thereby obtaining the image after brightness compensation. The SAR single-scene image brightness compensating method has advantages of effectively preventing black point phenomenon, reserving detail information of the image, and obtaining a satisfactory brightness compensation effect.

Description

technical field [0001] The invention belongs to the technical field of SAR image brightness compensation in the field of image processing, in particular to a SAR single-scene image brightness compensation method based on local histogram compression. Background technique [0002] The unique coherent imaging method of Synthetic Aperture Radar (SAR) enables it to penetrate clouds, rain and snow, and produce image products with higher resolution and contrast, so it is widely used in agriculture, disaster monitoring, geology, lakes, ocean monitoring and navigation, etc. field. The wide application and in-depth research of SAR images often require images with balanced brightness, moderate contrast, and consistent colors, so that SAR images can be used to make various DOM mosaic products and integrate them with geographic information systems. However, SAR is a microwave slant-range imaging radar. The brightness information of SAR images actually reflects the backscattering intensi...

AI Technical Summary

Problems solved by technology

[0004] There are some problems in the above brightness compensation methods: the frequency domain low-pass filtering method cannot guarantee that the pixel gray value of the background image does not exceed the original image, if some pixel values ​​of the background image are greater than the original image, the corresponding pixel gray value of the difference image Negative values ​​will appear in the brightness value, which will lose the corresponding detail information, and show black spots on the brightness compensation image

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