液晶投影机自动Gamma校正系统

为了增强液晶投影机显示的图像层次，建立了一套自动Gamma校正系统来补偿液晶本身的S形透过率特性曲线。系统控制驱动电路中每个通道的查找表输出从弱到强的信号，同时采用光电探测器自动测量投影机输出的光强，以此获得投影机的透过率特性曲线。系统中的软件根据此曲线自动生成Gamma数据，并实时写入到投影机驱动电路Gamma校正寄存器中。测试结果表明，经Gamma校正系统校正后的投影机输出光强曲线符合理想的幂指数函数，且光强误差在-1%～1％以内，能够重现输出图像的各个层次。

Automatic Gamma correction system for liquid crystal projector

In order to improve the image gradations of the liquid crystal(LC) projector,an automatic Gamma correction system was established to compensate for the S-shape transmittance character line of the LC.The system measures the luminance output of the LC projector using photocell by controlling each channel's look-up-table(LUT) in the driving circuit to output signals from small to large,so as to obtain the transmittance character line.Then the Gamma data are generated automatically according to the line and sent to the LUT real-time.Experimental results showed that after Gamma correction,the luminance outputted by the LC projector accorded perfectly with the theoretical power function.The percentage luminance error was within-1%~1%,and the outputted image recurred every gradation.