基于彩色数字图像处理的自动调焦技术

Automatic Focusing Technique Based on Color Image Processing

针对彩色图像讨论了基于数字图像处理技术的自动调焦算法.根据彩色图像的特点,选取了能够表现图像清晰度的两种矢量范数———L1范数和L2范数分别作为粗略调焦和精确调焦的评价函数,以实现系统在大范围内的精确调焦.为了提高图像的质量,采用了既能保持图像细节又能滤除脉冲和高斯噪声的中值滤波算法和均值滤波算法相结合的矢量中值均值滤波器.实验结果表明,本调焦算法能够在大范围内调节焦距,且具有较高的调焦精度,调焦速度较快.

Automatic focusing technique is an important method to obtain high quality image. For color image, automatic focusing algorithm is investigated basing on digital image processing in this paper. According to the characteristic of color image, two vector norms——L1 and L2, which can reveal the color image definition, are selected as evaluating functions to focus. L1 is used to cursorily focus and L2 is used to precisely focus. Therefore, automatic focusing in large range is realized. Combining vector median filter and mean value filter, vector median-mean filter, which can filter Gaussian noise and impulse noise and preserve fine details, is adopted. The result shows that the automatic focusing algorithm can adjust focus in wide range precisely and quickly.