samples/cpp/falsecolor.cpp

An example using applyColorMap function

#include "opencv2/imgproc.hpp"
#include "opencv2/imgcodecs.hpp"
#include "opencv2/highgui.hpp"
#include <iostream>
 
using namespace cv;
using namespace std;
 
enum MyShape{MyCIRCLE=0,MyRECTANGLE,MyELLIPSE};
 
struct ParamColorMap {
 int iColormap;
 Mat img;
};
 
String winName="False color";
static const String ColorMaps[] = { "Autumn", "Bone", "Jet", "Winter", "Rainbow", "Ocean", "Summer", "Spring",
 "Cool", "HSV", "Pink", "Hot", "Parula", "Magma", "Inferno", "Plasma", "Viridis",
 "Cividis", "Twilight", "Twilight Shifted", "Turbo", "Deep Green", "User defined (random)" };
 
static void TrackColorMap(int x, void *r)
{
 ParamColorMap *p = (ParamColorMap*)r;
 Mat dst;
 p->iColormap= x;
 if (x == COLORMAP_DEEPGREEN + 1)
 {
 Mat lutRND(256, 1, CV_8UC3);
 randu(lutRND, Scalar(0, 0, 0), Scalar(255, 255, 255));
 applyColorMap(p->img, dst, lutRND);
 }
 else
 applyColorMap(p->img,dst,p->iColormap);
 
 putText(dst, "Colormap : "+ColorMaps[p->iColormap], Point(10, 20), FONT_HERSHEY_SIMPLEX, 0.8, Scalar(255, 255, 255),2);
 imshow(winName, dst);
}
 
 
static Mat DrawMyImage(int thickness,int nbShape)
{
 Mat img=Mat::zeros(500,256*thickness+100,CV_8UC1);
 int offsetx = 50, offsety = 25;
 int lineLength = 50;
 
 for (int i=0;i<256;i++)
 line(img,Point(thickness*i+ offsetx, offsety),Point(thickness*i+ offsetx, offsety+ lineLength),Scalar(i), thickness);
 RNG r;
 Point center;
 int radius;
 int width,height;
 int angle;
 Rect rc;
 
 for (int i=1;i<=nbShape;i++)
 {
 int typeShape = r.uniform(MyCIRCLE, MyELLIPSE+1);
 switch (typeShape) {
 case MyCIRCLE:
 center = Point(r.uniform(offsetx,img.cols- offsetx), r.uniform(offsety + lineLength, img.rows - offsety));
 radius = r.uniform(1, min(offsetx, offsety));
 circle(img,center,radius,Scalar(i),-1);
 break;
 case MyRECTANGLE:
 center = Point(r.uniform(offsetx, img.cols - offsetx), r.uniform(offsety + lineLength, img.rows - offsety));
 width = r.uniform(1, min(offsetx, offsety));
 height = r.uniform(1, min(offsetx, offsety));
 rc = Rect(center-Point(width ,height )/2, center + Point(width , height )/2);
 rectangle(img,rc, Scalar(i), -1);
 break;
 case MyELLIPSE:
 center = Point(r.uniform(offsetx, img.cols - offsetx), r.uniform(offsety + lineLength, img.rows - offsety));
 width = r.uniform(1, min(offsetx, offsety));
 height = r.uniform(1, min(offsetx, offsety));
 angle = r.uniform(0, 180);
 ellipse(img, center,Size(width/2,height/2),angle,0,360, Scalar(i), -1);
 break;
 }
 }
 return img;
}
 
int main(int argc, char** argv)
{
 cout << "This program demonstrates the use of applyColorMap function.\n\n";
 
 ParamColorMap p;
 Mat img;
 
 if (argc > 1)
 img = imread(samples::findFile(argv[1]), IMREAD_GRAYSCALE);
 else
 img = DrawMyImage(2,256);
 
 p.img=img;
 p.iColormap=0;
 
 imshow("Gray image",img);
 namedWindow(winName);
 createTrackbar("colormap", winName, NULL, COLORMAP_DEEPGREEN + 1, TrackColorMap, (void*)&p);
 setTrackbarMin("colormap", winName, COLORMAP_AUTUMN);
 setTrackbarMax("colormap", winName, COLORMAP_DEEPGREEN + 1);
 setTrackbarPos("colormap", winName, COLORMAP_AUTUMN);
 
 TrackColorMap(0, (void*)&p);
 
 cout << "Press a key to exit" << endl;
 waitKey(0);
 return 0;
}