vc实现的图像信号处理，包括：256色转灰度图、对比度拉伸、二值化变换、反色、亮度增减、取对数、取指数、直方图均衡、灰度均衡、阈值变换、图像镜像.-vc achieve image signal processing, including: 256-color to grayscale, contrast stretching, binarization transformation, anti-color, brightness change, check on the number of c