Opencv-python滤镜系列(4): 颜色镜滤镜效果实现

颜色滤镜效果

实现原理：其实是利用伪彩色applyColorMap函数，对灰度图进行添加颜色滤镜。

OpenCV的定义12种colormap（色度图），可以应用于灰度图像，使用函数applycolormap产生伪彩色图像。

 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
    }

十二中颜色图如下：

C++接口：

using namespace cv;
Mat im_gray = imread("pluto.jpg", IMREAD_GRAYSCALE);
Mat im_color;
applyColorMap(im_gray, im_color, COLORMAP_JET);

Python接口：

import cv2
im_gray = cv2.imread("pluto.jpg", cv2.IMREAD_GRAYSCALE)
im_color = cv2.applyColorMap(im_gray, cv2.COLORMAP_JET)

颜色滤镜C++代码实现：

#include 
#include 
#include 
#include 
#include
using namespace cv;
using namespace std;
int main()
{
	Mat src0= imread("C://timg.jpg");
	Mat src;
	resize(src0, src, cv::Size(300, 300));
	int width = src.cols;
	int heigh = src.rows;
	Mat gray;
	Mat imgColor[12];
	Mat display(heigh * 3, width * 4, CV_8UC3);
	cvtColor(src, gray, CV_BGR2GRAY);
	for (int i = 0; i<12; i++)
	{
		applyColorMap(gray, imgColor[i], i);
		int x = i % 4;
		int y = i / 4;
		Mat displayROI = display(Rect(x*width, y*heigh, width, heigh));
		resize(imgColor[i], displayROI, displayROI.size());
	}
	imshow("colorImg", display);
	waitKey();
}

另外，可以利用色图映射公式来进行颜色滤镜效果实现：

映射公式：

b, g, r = src_img[i][j]
x = int(g / 4 + int(b / 32) * 64)
y = int(r / 4 + int(b % 32) * 64)

参考博客：
https://blog.csdn.net/u013381011/article/details/78341861
https://blog.csdn.net/yangtrees/article/details/9096435
https://baijiahao.baidu.com/s?id=1625787844890494432&wfr=spider&for=pc