Department of Electronic Engineering, La Trobe University, Bundoora, Victoria 3086, Australia.
IEEE Trans Image Process. 2011 May;20(5):1249-61. doi: 10.1109/TIP.2010.2092441. Epub 2010 Nov 15.
Enhancement of contrast and sharpness of an image is required in many applications. Unsharp masking is a classical tool for sharpness enhancement. We propose a generalized unsharp masking algorithm using the exploratory data model as a unified framework. The proposed algorithm is designed to address three issues: (1) simultaneously enhancing contrast and sharpness by means of individual treatment of the model component and the residual, (2) reducing the halo effect by means of an edge-preserving filter, and (3) solving the out-of-range problem by means of log-ratio and tangent operations. We also present a study of the properties of the log-ratio operations and reveal a new connection between the Bregman divergence and the generalized linear systems. This connection not only provides a novel insight into the geometrical property of such systems, but also opens a new pathway for system development. We present a new system called the tangent system which is based upon a specific Bregman divergence. Experimental results, which are comparable to recently published results, show that the proposed algorithm is able to significantly improve the contrast and sharpness of an image. In the proposed algorithm, the user can adjust the two parameters controlling the contrast and sharpness to produce the desired results. This makes the proposed algorithm practically useful.
在许多应用中，都需要增强图像的对比度和锐度。 不清晰掩模是一种用于锐化增强的经典工具。 我们提出了一种使用探索性数据模型作为统一框架的广义不清晰掩模算法。 所提出的算法旨在解决三个问题：（1）通过对模型分量和残差进行单独处理，同时增强对比度和锐度，（2）通过边缘保持滤波器减少晕影效应，（3）通过对数比和正切运算解决超出范围的问题。 我们还研究了对数比运算的性质，并揭示了 Bregman 散度和广义线性系统之间的新联系。 这种联系不仅为这些系统的几何性质提供了新的见解，而且为系统开发开辟了新的途径。 我们提出了一种称为正切系统的新系统，它基于特定的 Bregman 散度。 可与最近发表的结果相媲美的实验结果表明，所提出的算法能够显著提高图像的对比度和锐度。 在提出的算法中，用户可以调整控制对比度和锐度的两个参数以产生所需的结果。 这使得所提出的算法在实际中非常有用。
