Modified fast climbing search auto-focus algorithm with adaptive step size searching technique for digital camera
Modified fast climbing search auto-focus algorithm with adaptive step size searching technique for digital camera
复制标题
DOI：
10.1109/tce.2003.1209511
复制
发表时间：
2003-05-01
影响因子：
4.3
通讯作者：
Hong, ZL
中科院分区：
文献类型：
--
作者：
He, J;Zhou, RZ;Hong, ZL
提出了一种实用的数码相机实时自动对焦算法，提高了自动对焦过程的可靠性和速度，特别适用于百万像素级的高清晰度相机。该算法除了采用聚焦值函数外，还采用了阈值梯度和边缘点计数技术，取代了传统的仅采用聚焦值函数的两阶段爬山搜索算法I。此外，还提出了一种相对差比电路，它可以实现自适应步长搜索，以提高搜索速度。在百万像素数码相机样机上采用改进算法，验证了实时自动对焦功能。该算法已在0.25um CMOS数字工艺的测试相机芯片上实现。
A practical real-time auto-focus algorithm for digital camera is presented, and it improves the reliability and speed of auto-focus process, especially suitable for mega-pixel high definition camera. The proposed algorithm adopts threshold gradient and edge point count technique besides focus value function, instead of traditional two-stage climbing search algorithm I that uses focus value function only. Additionally, a relative difference ratio circuit is also proposed, which can implement adaptive step size searching to increase the searching speed. By adopting the modified algorithm on the prototype of our mega-pixel digital camera, real-time auto-focus function is verified. The proposed algorithm is implemented in test camera chip that has been manufactured in 0.25um CMOS digital process.