基于平稳小波变换和亮度序的局部特征描述子

Local Feature Descriptor Based on Stationary Wavelet Transform and Intensity Order

局部区域的非线性亮度变化通常会造成局部特征描述子的不稳定。针对该问题,在平稳小波变换和亮度序的基础上,提出一种局部特征描述子。利用Hessian-Affine算子检测仿射协变区域,对检测区域进行平稳小波变换分解,将不同尺度的多个低频子带作为支持区域,多支持区域的使用可以有效地降低图像扭曲带来的不利影响。采用亮度序对支持区域进行区域划分,确保所构造描述子对单调亮度变化具有不变性,并在局部旋转不变坐标系下计算局部特征描述子。实验结果表明,该描述子在视角、线性亮度和JPEG压缩等变化下具有较好的鲁棒性。

The nonlinear illumination changes of local region frequently have a negative impact on the stability of local feature descriptor. In order to solve the problem,a local feature descriptor based on Stationary Wavelet Transform（ SWT）and intensity order is proposed. The affine covariant region is detected by using Hessian-Affine detector. The detected region is decomposed by SWT to get multiple low-frequency subbands of different scales as support regions, and the used multiple support regions can effectively reduce the negative impact which is caused by image distortion. The support regions are divided by intensity orders and this ensures that the proposed descriptor is invariant to the monotonous illumination changes. The local feature descriptor is obtained under the local rotation invariant coordinate system.Experimental results show the robustness of the proposed descriptor for the image with viewpoint changes,linear illumination changes, JPEG compression changes and so on.