Ferrari José A, Flores Jorge L
Instituto de Física, Facultad de Ingeniería, Universidad de la República, Julio Herrera y Reissig 565, Montevideo, Uruguay.
Appl Opt. 2010 Jun 10;49(17):3291-6. doi: 10.1364/AO.49.003291.
We present an image processing method for nondirectional edge extraction/enhancement. The method is based on the capability of twisted-nematic liquid-crystal displays (LCDs) to traduce the image information in changes of the state of polarization of the light, which allows us to generate simultaneously a "positive" and a "negative" (i.e., contrast-reversed) replica of the digital image displayed on the LCD. The negative image is low-pass filtered in a novel polarization-selective 4f optical processor. When the smoothed negative image is imagined together with the original image, an image with nondirectional edge enhancement is obtained. Unlike other Fourier methods presented in the literature, the proposed technique provides a simple way to control the relative amount of high frequencies present in the final image. The proposed method does not involve numerical processing, and, thus, it could be a useful tool for edge extraction/enhancement in large images in real-time applications. Validation experiments are presented.
我们提出了一种用于非定向边缘提取/增强的图像处理方法。该方法基于扭曲向列型液晶显示器（LCD）将图像信息转化为光偏振状态变化的能力，这使我们能够同时生成LCD上显示的数字图像的“正”副本和“负”（即对比度反转）副本。负图像在一种新型的偏振选择性4f光学处理器中进行低通滤波。当将平滑后的负图像与原始图像一起想象时，可获得具有非定向边缘增强的图像。与文献中提出的其他傅里叶方法不同，所提出的技术提供了一种简单的方法来控制最终图像中高频成分的相对量。所提出的方法不涉及数值处理，因此，它可能是实时应用中大型图像边缘提取/增强的有用工具。文中还给出了验证实验。
