OpenCV 自带颜色表实现各种滤镜

一、知识点
1、void applyColorMap(InputArray src, OutputArray dst, int colormap);

(1)、通过给定的颜色映射表，将灰度图像或伪彩色图像转换为全彩色图像。

(2)、参数说明:

src: 源图像，灰度或彩色，类型为CV_8UC1或CV_8UC3。 如果是CV_8UC3，则使用cv::COLOR_BGR2GRAY在内部生成CV_8UC1图像。

dst: 给源图像做颜色映射后的结果图像。

colormap: 颜色映射需要的enum类型，具体见(3)。

(3)、

enum ColormapTypes

{

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, //!< 

COLORMAP_PARULA = 12, //!< 

COLORMAP_MAGMA = 13, //!< 

COLORMAP_INFERNO = 14, //!< 

COLORMAP_PLASMA = 15, //!< 

COLORMAP_VIRIDIS = 16, //!< 

COLORMAP_CIVIDIS = 17, //!< 

COLORMAP_TWILIGHT = 18, //!< 

COLORMAP_TWILIGHT_SHIFTED = 19, //!< 

COLORMAP_TURBO = 20, //!< 

COLORMAP_DEEPGREEN = 21 //!< 

};

(4)、此功能通常用于增强图像的可视化效果，特别是在处理诸如热图(heatmaps)等数据可视化时非常有用。

二、示例代码: 循环切换各种滤镜

#include <iostream>
#include <opencv2/opencv.hpp>


void TestColorMap(cv::Mat & src)
{
    int i_color_map[] = {
        cv::COLORMAP_AUTUMN,
        cv::COLORMAP_BONE,
        cv::COLORMAP_JET,
        cv::COLORMAP_WINTER,
        cv::COLORMAP_RAINBOW,
        cv::COLORMAP_OCEAN,
        cv::COLORMAP_SUMMER,
        cv::COLORMAP_SPRING,
        cv::COLORMAP_COOL,
        cv::COLORMAP_HSV,
        cv::COLORMAP_PINK,
        cv::COLORMAP_HOT,
        cv::COLORMAP_PARULA,
        cv::COLORMAP_MAGMA,
        cv::COLORMAP_INFERNO,
        cv::COLORMAP_PLASMA,
        cv::COLORMAP_VIRIDIS,
        cv::COLORMAP_CIVIDIS,
        cv::COLORMAP_TWILIGHT,
        cv::COLORMAP_TWILIGHT_SHIFTED,
        cv::COLORMAP_TURBO,
        cv::COLORMAP_DEEPGREEN
    };
    
    cv::Mat dst;
    int index = 0;

    while (true)
    {
        int c = cv::waitKey(1000);
        if (c == 27)
        {
            break;
        }

        cv::applyColorMap(src, dst, i_color_map[index % 22]);
        cv::imshow("颜色风格", dst);

        index++;
    }
}


int main()
{
    cv::Mat src = cv::imread("../images/8.png");
    if (src.empty())
    {
        std::cout << "load src image error..." << std::endl;
        return -1;
    }
    cv::imshow("原始图像", src);

    TestColorMap(src);
    
    return 0;
}