索引图-查表-颜色缩减

 1 // https://docs.opencv.org/3.2.0/d2/de8/group__core__array.html#gab55b8d062b7f5587720ede032d34156f
 2 
 3 //其实就是颜色缩减，索引图
 4 #include<opencv2/opencv.hpp>
 5 
 6 using namespace cv;
 7 
 8 int main()
 9 {
10     //<1> 构建一个Mat 表
11     Mat look_up_table(1, 256, CV_8U);
12     for (int i = 0; i < 256; i++)
13     {
14         look_up_table.ptr<uchar>(0)[i] = 10 * (i / 10);
15     }
16     //<2> 利用LUT函数查找
17     Mat srcImage = imread("lena.jpg", -1);
18     Mat dstImage;
19     LUT(srcImage, look_up_table, dstImage);
20     imshow("look_up_table", look_up_table);
21     namedWindow("srcImage", WINDOW_NORMAL);
22     imshow("srcImage", srcImage);
23     namedWindow("dstImage", WINDOW_NORMAL);
24     imshow("dstImage", dstImage);
25     waitKey(0);
26     return 1;
27 }

其实就是一句话概括如下：（类似于统计直方图）

dstImage.ptr<uchar>(y)[x] = look_up_table[0][dstImage.ptr<uchar>(y)[x]];