摘要
自动对焦可以快速、准确地将镜头调节到最佳位置,但目前该方式在算法和电路设计上还不够成熟,制约了它的应用。通过优化电路设计,选用TMS320VC5509A、FIFO和串口FLASH等低功耗、小尺寸封装芯片组成低功耗自动对焦电路,并基于Sobel算子的Tenengrad的改进图像边缘能量评价函数,采用可变窗口、合适的阈值,配合粗调(定步长)和精调(可变步长)搜索算法,设计实现了一种手持红外热像仪快速、准确地自动对焦的电路。实验结果表明,该方法高效可行,不仅能实现手持红外热像仪对目标的快速捕获,并能降低操作强度。
Auto-focusing could adjust the lens to the best positions fast and accurately, however, it is not widely used in handheld infrared camera, mainly due to the reason that whose algorithm and circuit design is not fully mature. By optimi zing the circuit design and selecting the chips with low power and small package size such as TMS320VC5509A, FIFO, seri al FLASH, and so on, an auto focus circuit is designed and implemented in this paper. The Tenengrad function based Sobel operator is chosen as the evaluation function of edge energy and improved to reduce the computational cost, based on which, variable window, the coarse（fixed step） and fine tuning（variable step） search algorithm are proposed to achieve fast and ac curate automatic focusing of handhold infrared camera under different circumstance. Experimental results show that the pro- posed method is effective and efficient, which could help handheld infrared camera capture the target quickly, and reduce op- erating strength.
出处
《光学与光电技术》
2012年第3期74-77,共4页
Optics & Optoelectronic Technology
