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多尺度窗口下的自适应纹理滤波算法

Adaptive Texture Filtering Algorithm Based on Multi-Scale Window

  • 摘要: 为了解决现有纹理滤波方法无法有效地生成具有纹理-结构区分度高的结构测度图像, 以及抑制强梯度纹理和保持结构稳定的问题, 提出一种多尺度窗口下的自适应纹理滤波算法. 首先提出一种具有强梯度纹理抑制和精细结构保持的圆形梯度算子, 利用每个像点的圆形邻域范围内多方向、多结构、多通道和多尺度信息计算纹理和结构之间的差异性, 并将其输入至定向各向异性结构度量框架中, 获得具有高对比度的结构测度图像; 然后利用高斯混合模型和 EM 算法实现对纹理和结构的分离; 最后在多尺度窗口下对像点邻域存在结构的可能性进行评估, 提出一种自适应滤波核尺度选择机制, 即纹理区域获得大尺寸滤波核, 结构区域获得小尺寸滤波核, 实现尺度自适应的滤波效果. 使用 F1 评价指标在图像平滑领域经典图像数据集上进行评估, 以及使用 PSNR 和 SSIM 评价指标在 BSD500数据集上进行实验的结果表明, 相较于对比滤波方法, 所提算法既可以有效地抑制强梯度纹理, 又可以保持精细结构尖端区域的稳定和结构周围的整洁.

     

    Abstract: The current texture filtering methods often struggle to generate structural measurement image with high texture-structure differentiation and have difficulty suppressing texture with strong gradient while maintaining structural stability. To address the problem, an adaptive texture filtering algorithm based on multi-scale window is proposed. Firstly, a circular gradient operator is designed to suppress texture with strong gradient while simultaneously preserving intricate structure. It utilizes the multi-direction, multi-structure, multi-channel, and multi-scale information within each pixel’s circular neighbourhood to compute the difference between texture and structure, and then input them into the framework of Directional Anisotropic Structure Measurement (DASM) to obtain high-contrast structural measurement image. Secondly, a texture-structure separation method based on Gaussian mixture model and EM algorithm is proposed. Finally, a mechanism for adaptive filter kernel selection based on the possibility assessment of the existence of structure in the neighborhood of pixel under multi-scale window is proposed. It can enable the pixel located in the texture to obtain large-scale filter kernel, and the pixel located in the structure to obtain small-scale filter kernel, thus achieving scale-adaptive filtering effect. In the experiment, the classical images in the field of image smoothing and the images from the BSD500 dataset are used as the test data, and the F1, PSNR, and SSIM are adopted as the objective evaluation matrics. The results show that the proposed algorithm is able to effectively suppress texture with strong gradient and preserve the stability and aesthetics of intricate structural sharp region, compared with existing texture filtering methods.

     

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