阵列像素器件投影显示系统中自动对焦评价函数研究

数字投影显示已成为现代数字显示领域的主流，阵列像素器件投影成像的的精确会聚，直接决定了显示的效果。阵列像素器件的自动对焦，是实现生产自动化的关键技术。以CCD(电荷耦合器件)采集阵列像素器件的局部投影图像为基础，试验和分析了梯度算子、拉普拉斯算子、Sobel算子、Prewitt算子、方差函数和熵函数评价方法在阵列像素器件大屏幕投影显示系统中自动对焦的作用及性能。实验表明，方差算子具有良好的稳定性和对噪声的不敏感性，调节效果较好，可以作为这一特殊系统中的评价方法。

Research of Sharpness Evaluation Function in Array Pixel Device Projection Display's Auto-Focusing System

Digital projection display has become the mainstream in modern display field. Accurate focusing of the array pixel devices in these systems determines the quality of the displaying effect. Auto-focusing of the pixel devices is the key technique to rise the productivity. Based on the images captured by CCD (Charge Coupled Device) in array pixel device projector, several sharpness evaluation functions, such as gradient operator, Laplacian operator, Sobel operator, Prewitt operator, variance method, and entropy method, are analyzed. Using these evaluation functions, automatic focusing is realized. The characteristics and the auto-focusing result is compared with each other. The experiments indicate that good stability and insensitivity to noise and good regulation effect can be obtainted by variance method.