Focusing techniques
Focusing techniques
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对焦技巧
DOI：
10.1117/12.132073
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发表时间：
1992
期刊：
影响因子：
--
通讯作者：
Arman Nikzad
中科院分区：
文献类型：
--
作者：
Murali Subbarao;Tae;Arman Nikzad
我们使用图像形成的近轴几何光学模型来推导一套相机聚焦技术。这些技术不需要相机校准，但涉及相机参数空间的搜索。这些技术被证明在理论上是合理的。它们包括未滤波、低通滤波、高通滤波和带通滤波图像的能量最大化。结果表明，在存在高空间频率、噪声和混叠的情况下，基于带通滤波器的聚焦技术表现良好。聚焦技术在名为 SPARCS 的原型相机系统上实现。简要描述了SPARCS的体系结构。通过实验比较不同技术的性能。所有技术均表现良好。其中一种——低通滤波图像梯度能量——具有更好的整体特性，推荐用于实际应用。
We use the paraxial geometric optics model of image formation to derive a set of camera focusing techniques. These techniques do not require calibration of cameras but involve a search of the camera parameter space. The techniques are proved to be theoretically sound. They include energy maximization of unfiltered, low-pass filtered, high-pass filtered, and band-pass filtered images. It is shown that in the presence of high spatial frequencies, noise, and aliasing, focusing techniques based on band-pass filters perform well. The focusing techniques are implemented on a prototype camera system named SPARCS. The architecture of SPARCS is described briefly. The performance of the different techniques are compared experimentally. All techniques are found to perform well. One of them -- the energy of low pass filtered image gradient -- which has better overall characteristics is recommended for practical applications.