Abstract:
The accuracy of medical image registration based on mutual information can reach sub-pixel level, with high accuracy and good robustness. However, frequent involving a huge amount of floating-point calculation, the rate of registration is very slow and can not achieve real-time requirements of clinical use. Because the rate of mutual information is relative to the amount of gray-scales, this paper presents a method based on a nonlinear grayscale mapping method which uses the gradient information of the image. A different image is decomposited and recomposited by a wavelet. Experimental result shows the method can reduce the gray scale of a image at the premise of preserving the image details. Moreover, this algorithm reduces the registration time and maintain the accuracy of registration.
Key words:
grayscale compression,
gradient,
medical image registration
摘要: 基于互信息的医学图像配准,其配准精度可以达到亚像素水平,精度高且鲁棒性好,但互信息的巨大计算量使配准速度较慢,不能达到临床使用要求,而互信息的计算速度与图像的灰度阶数有关。为此,针对互信息由于图像灰度级数过多造成互信息计算量大的问题,提出一种基于图像梯度的灰度压缩算法。算法采用图像的梯度信息,根据图像梯度对图像进行非线性灰度映射,同时利用小波对差异图像进行分解和重构。实验结果证明,该算法能减少图像灰度阶数,同时较好地保留图像的细节信息,在保持配准精度的前提下减少配准时间。
关键词:
灰度压缩,
梯度,
医学图像配准
CLC Number:
ZHOU Zhi-Yong, ZHANG Chao. Grayscale Compression Based on Image Gradient in Medical Image Registration[J]. Computer Engineering, 2011, 37(7): 237-240.
周志勇, 张涛. 医学图像配准中基于图像梯度的灰度压缩[J]. 计算机工程, 2011, 37(7): 237-240.