关键词: 小波分解, 改进双边滤波, Retinex算法, 改进阈值函数, 离散小波反变换, 分段性线性变换

Abstract: Aiming at the image gray phenomenon and halo phenomenon based on single-scale Retinex algorithm, gray phenomenon based on bilateral filtering Retinex algorithm and noise amplification phenomenon. An improved two-sided filtering based on wavelet transform and a modified threshold function denoising algorithm are proposed. The image is decomposed by wavelet transform to obtain the low-frequency and high-frequency coefficients of the image. The low-frequency coefficients of the image are processed by improved bilateral filtering Retinex algorithm, and the high-frequency coefficients are processed by improved threshold function. The enhanced reconstructed image is obtained by inverse discrete wavelet transform. The reconstructed image is reconstructed like segmented linear transformation, enhance image contrast. The experimental results show that this method avoids the phenomenon of image gray and halo, and effectively removes noise, rich details and strong contrast, which lays the foundation for image follow-up processing.

Key words: wavelet decomposition, improved bilateral filtering, Retinex algorithm, improved threshold function, discrete wavelet inverse transform, piecewise linear transform