OpenCV  4.1.0
Open Source Computer Vision
samples/cpp/tutorial_code/photo/non_photorealistic_rendering/npr_demo.cpp

An example using non-photorealistic line drawing functions

/*
* npr_demo.cpp
*
* Author:
* Siddharth Kherada <siddharthkherada27[at]gmail[dot]com>
*
* This tutorial demonstrates how to use OpenCV Non-Photorealistic Rendering Module.
* 1) Edge Preserve Smoothing
* -> Using Normalized convolution Filter
* -> Using Recursive Filter
* 2) Detail Enhancement
* 3) Pencil sketch/Color Pencil Drawing
* 4) Stylization
*
*/
#include <iostream>
using namespace std;
using namespace cv;
int main(int argc, char* argv[])
{
int num,type;
CommandLineParser parser(argc, argv, "{@input | ../data/lena.jpg | input image}");
Mat src = imread(parser.get<String>("@input"), IMREAD_COLOR);
if(src.empty())
{
cout << "Could not open or find the image!\n" << endl;
cout << "Usage: " << argv[0] << " <Input image>" << endl;
exit(0);
}
cout << endl;
cout << " Edge Preserve Filter" << endl;
cout << "----------------------" << endl;
cout << "Options: " << endl;
cout << endl;
cout << "1) Edge Preserve Smoothing" << endl;
cout << " -> Using Normalized convolution Filter" << endl;
cout << " -> Using Recursive Filter" << endl;
cout << "2) Detail Enhancement" << endl;
cout << "3) Pencil sketch/Color Pencil Drawing" << endl;
cout << "4) Stylization" << endl;
cout << endl;
cout << "Press number 1-4 to choose from above techniques: ";
cin >> num;
Mat img;
if(num == 1)
{
cout << endl;
cout << "Press 1 for Normalized Convolution Filter and 2 for Recursive Filter: ";
cin >> type;
edgePreservingFilter(src,img,type);
imshow("Edge Preserve Smoothing",img);
}
else if(num == 2)
{
detailEnhance(src,img);
imshow("Detail Enhanced",img);
}
else if(num == 3)
{
Mat img1;
pencilSketch(src,img1, img, 10 , 0.1f, 0.03f);
imshow("Pencil Sketch",img1);
imshow("Color Pencil Sketch",img);
}
else if(num == 4)
{
stylization(src,img);
imshow("Stylization",img);
}
waitKey(0);
}