怀旧效果处理
怀旧效果一般用在一些相片处理上，使整张相片呈棕褐色，仿佛相片已保存很久，已经发黄。方法是对每个像素的RGB分量按照公式（4-2）赋值：
//怀旧Mat OldStyle(Mat src) {Mat output(src.size(), CV_8UC3);for (int i = 0; i < src.rows; i++) {for (int j = 0; j < src.cols; j++) {float R = src.at<Vec3b>(i, j)[2] * 0.393 + src.at<Vec3b>(i, j)[1] * 0.769 + src.at<Vec3b>(i, j)[0] * 0.189;float G = src.at<Vec3b>(i, j)[2] * 0.349 + src.at<Vec3b>(i, j)[1] * 0.686 + src.at<Vec3b>(i, j)[0] * 0.168;float B = src.at<Vec3b>(i, j)[2] * 0.272 + src.at<Vec3b>(i, j)[1] * 0.534 + src.at<Vec3b>(i, j)[0] * 0.131;//防止某个颜色分量的值溢出R = R > 255 ? 255 : R;G = G > 255 ? 255 : G;B = B > 255 ? 255 : B;output.at<Vec3b>(i, j)[2] = R; //Routput.at<Vec3b>(i, j)[1] = G; //Goutput.at<Vec3b>(i, j)[0] = B; //B}}return output;}
