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基于邻域特征搜索与局部单应性变换的图像拼接算法

Image Stitching Algorithm Based on Neighborhood Feature Search and Local Homography Transformation

  • 摘要: 图像拼接通过融合具有重叠区域的图像以生成宽视角图像,有效扩展了单镜头视野。典型的逼近投影变换图像拼接(as-projective-as-possible image stitching, APAP)算法虽拼接精度较高,但计算效率偏低。为此,本文提出一种基于邻域特征搜索与局部单应性变换的图像拼接算法,以兼顾精度与效率。该算法首先将源图像均匀划分成多个矩形网格,通过邻域特征搜索策略获取各网格中心邻域内的特征点对,并采用最小二乘法计算局部单应性矩阵,再通过全局与局部变换的线性加权实现平滑过渡。随后通过透视变换实现源图像与目标图像的对齐与叠加,并采用基于距离变换的羽化融合消除拼接缝。为验证算法的可行性,开展计算机仿真与多场景图像拼接实验。结果表明:本文算法在抗噪声能力上优于全局单应性变换(global homography transformation, GHT)、尽可能自然投影变换(adaptive as-natural-as-possible image stitching, AANAP)、接缝引导的局部对齐和拼接(seam-guided local alignment and stitching, SLAS)及APAP算法,其均方根误差较APAP减少8.9%,峰值信噪比、结构相似性指数分别提高11.4%与12.5%,耗时减少29.4%。本研究通过简化局部单应性矩阵计算,在显著提升效率的同时保障了拼接质量,为图像拼接技术的发展提供了新思路。

     

    Abstract: Image stitching effectively extends the field of view of a single lens by integrating images with overlapping regions to generate wide-angle panoramas. The typical as-projective-as-possible (APAP) image stitching algorithm achieves high alignment accuracy but suffers from low computational efficiency. To address this issue, an image stitching algorithm based on neighborhood feature search and local homography transformation was proposed to balance accuracy and efficiency. The source image was first divided uniformly into multiple rectangular grids, and feature pairs within the neighborhood of each grid center were obtained using a neighborhood feature search strategy. The local homography matrix for each grid was then calculated via the least squares method, and a smooth transition was achieved through linear weighting of global and local transformations. Subsequently, the alignment and overlay of the source and target images were realized through perspective transformation, and seam artifacts were eliminated using a distance transform-based feathering fusion method. To validate the feasibility of the proposed algorithm, computer simulations and multi-scene image stitching experiments were conducted. The results demonstrate that the proposed algorithm outperforms global homography transformation (GHT), adaptive as-natural-as-possible (AANAP), seam-guided local alignment and stitching (SLAS), and APAP algorithms in terms of noise resistance. Compared with APAP, the root mean square error is reduced by 8.9%, while the peak signal-to-noise ratio and structural similarity index are improved by 11.4% and 12.5%, respectively, with a 29.4% reduction in computational time. By simplifying the computation of the local homography matrix, computational efficiency is significantly enhanced while stitching quality is maintained, providing a new perspective for the development of image stitching technology.

     

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