jin-yc10 / colormaps-opencv

Implements colormaps for use in OpenCV.

Colormaps in OpenCV

Description

This repository implements colormaps for use in OpenCV. This version now has the same interface as the colormaps in OpenCV 2.4+, so supporting multiple versions of OpenCV is easier.

Currently the following GNU Octave/MATLAB equivalent colormaps are implemented:

• Autumn
• Bone
• Cool
• Hot
• HSV
• Jet
• Ocean
• Pink
• Rainbow
• Spring
• Summer
• Winter

Feel free to fork the project and add your own colormaps. Please make a pull request to this branch then, so everybody can use your work.

API

You only need applyColorMap to apply a colormap on a given image:

void applyColorMap(InputArray src, OutputArray dst, int colormap)

The following sample code reads the path to an image from command line, applies a Jet colormap on it and shows the result:

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include "colormap.hpp"

using namespace cv;

int main(int argc, const char *argv[]) {
    // Get the path to the image, if it was given
    // if no arguments were given.
    string filename;
    if (argc > 1) {
        filename = string(argv[1]);
    }
	// The following lines show how to apply a colormap on a given image
	// and show it with cv::imshow example with an image. An exception is
	// thrown if the path to the image is invalid.
	if(!filename.empty()) {
        Mat img0 = imread(filename);
        // Throw an exception, if the image can't be read:
        if(img0.empty()) {
            CV_Error(CV_StsBadArg, "Sample image is empty. Please adjust your path, so it points to a valid input image!");
        }
        // Holds the colormap version of the image:
        Mat cm_img0;
        // Apply the colormap:
        applyColorMap(img0, cm_img0, COLORMAP_JET);
        // Show the result:
        imshow("cm_img0", cm_img0);
        waitKey(0);
	}

	return 0;
}

The available colormaps are:

enum
{
    COLORMAP_AUTUMN = 0,
    COLORMAP_BONE = 1,
    COLORMAP_JET = 2,
    COLORMAP_WINTER = 3,
    COLORMAP_RAINBOW = 4,
    COLORMAP_OCEAN = 5,
    COLORMAP_SUMMER = 6,
    COLORMAP_SPRING = 7,
    COLORMAP_COOL = 8,
    COLORMAP_HSV = 9,
    COLORMAP_PINK = 10,
    COLORMAP_HOT = 11
}

Demo

Please have a look at the demo, to see the colormaps in action and learn how to use the colormaps. If you want to apply a Jet colormap on a given image, then call the demo with:

./cm_demo /path/to/your/image.ext

Or if you just want to generate the color scales, then call the demo with:

./cm_demo

(Replace ./cm_demo with cm_demo.exe if you are running Windows!)

Building the demo

The project comes as a CMake project, so building it is as simple as:

philipp@mango:~/some/dir/colormaps-opencv$ mkdir build
philipp@mango:~/some/dir/colormaps-opencv$ cd build
philipp@mango:~/some/dir/colormaps-opencv/build$ cmake ..
philipp@mango:~/some/dir/colormaps-opencv/build$ make
philipp@mango:~/some/dir/colormaps-opencv/build$ ./cm_demo path/to/your/image.ext

Or if you use MinGW on Windows:

C:\some\dir\colormaps-opencv> mkdir build
C:\some\dir\colormaps-opencv> cd build
C:\some\dir\colormaps-opencv\build> cmake -G "MinGW Makefiles" ..
C:\some\dir\colormaps-opencv\build> mingw32-make
C:\some\dir\colormaps-opencv\build> cm_demo.exe /path/to/your/image.ext

Or if you are using Visual Studio, you can generate yourself a solution like this (please adjust to your version):

C:\some\dir\colormaps-opencv> mkdir build
C:\some\dir\colormaps-opencv> cd build
C:\some\dir\colormaps-opencv\build> cmake -G "Visual Studio 9 2008" ..