研究了用频域法实现圆环形目标物计数的方法。对空域中含有圆环形目标物的二值图像,经傅里叶变换后在频域内进行滤波,再经傅里叶反变换后取一阈值进行处理,则对应于圆环形目标物即变为一个实心体,然后对实心体进行计数即可实现对圆环形目标物的计数。对该方法进行了数学描述,并分别用模拟图像和实际图像进行了实验。结果表明,该方法消除噪声的效果好,对部分封闭圆的检测同样有效,且可用于目标物有粘连的情况。该方法对圆环形目标物的尺寸相差不大的情况更为有效。

The method of counting for circular ring objects in frequency domain is proposed. A binarized image with circular rings is processed by Fourier transformation and filtered in frequency domain, then inverse Fourier transformation is carried on. After selecting a suitable threshold, the circular rings become solid particles individually. The number of circular rings is obtained through counting the solid particles. The mathematical model is established and the experimental results for both simulated and real images are also given. The method is robust to noise and the detection for partially occluded circular rings is also available. The method can also be applied to the situation that some objects are overlapped. The method is more effective when the size of the objects in the image is similar to each other.