OpenCV2:幼兒園篇 第一章 創建圖像並顯示

一.簡介

相當於在PS中,新建一個畫布

cv::Mat 類和 lplimage / cvMat結構體都可以表示一張圖像

 

二.構造函數創建圖像

// 創建一個空矩陣
cv::Mat image1;

// 創建一個6行6列的8位1通道的矩陣
cv::Mat image2(6, 6, CV_8UC1);

// 創建一個7行7列的8位3通道的矩陣
cv::Mat image3(cv::Size(7, 7), CV_8UC3);    

cv::Mat image4(8, 8, CV_32FC2, cv::Scalar(1, 3));
cv::Mat image4(10, 8, CV_8UC1, cv::Scalar(5));

cv::Mat image5(cv::Size(9, 9), CV_8UC3, cv::Scalar(1, 2, 3));
        
cv::Mat image6(image2);

 

 

三.create()創建圖像

Mat m(2,2,CV_8UC3);
m.create(3,2,CV_8UC2);

 

 

五.單窗口顯示多張圖像

cv::resize()  //圖像縮放

cv::showManyImages()  //顯示多張圖像

 

#include <opencv2/core/core.hpp>
#include <opencv2/highgui/highgui.hpp>
#include <opencv2/imgproc/imgproc.hpp>
#include <iostream>

using namespace cv;

void showManyImages(const std::vector<cv::Mat>& srcImages, cv::Size imgSize)
{
	int nNumImages = srcImages.size();
	cv::Size nSizeWindows;
	if(nNumImages > 12)
	{
		std::cout << "Not more than 12 images!" << std::endl;
		return ;
	}

	// 根據圖片序列數量來確定分割小窗口形態
	switch(nNumImages)
	{
		case 1: nSizeWindows = cv::Size(1,1);break;
		case 2: nSizeWindows = cv::Size(2,1);break;
		case 3:
		case 4: nSizeWindows = cv::Size(2,2);break;
		case 5: 
		case 6: nSizeWindows = cv::Size(3,2);break;
		case 7:
		case 8: nSizeWindows = cv::Size(4,2);break;
		case 9: nSizeWindows = cv::Size(3,3);break;
		default: nSizeWindows = cv::Size(4,3);break;
	}

	// 設置小圖像尺寸 間隙 邊界
	int nShowImageSize = 200;
	int nSplitLineSize = 15;
	int nAroundLineSize = 50;

	// 創建輸出圖像 圖像大小根據輸入源確定
	const int imagesHeight = nShowImageSize * nSizeWindows.width + nAroundLineSize + (nSizeWindows.width - 1) * nSplitLineSize;
	const int imagesWidth = nShowImageSize * nSizeWindows.height + nAroundLineSize + (nSizeWindows.height - 1) * nSplitLineSize;
	std::cout << imagesWidth << " " << imagesHeight <<std::endl;

	cv::Mat showWindowImages(imagesWidth, imagesHeight, CV_8UC3, cv::Scalar(0, 0, 0));

	//提取對應小圖像的左上角坐標X Y
	int posX = (showWindowImages.cols - (nShowImageSize * nSizeWindows.width + (nSizeWindows.width - 1) * nSplitLineSize))/2;
	int posY = (showWindowImages.rows - (nShowImageSize * nSizeWindows.height + (nSizeWindows.height - 1) * nSplitLineSize)) / 2;

	std::cout << posX << " " << posY << std::endl;

	int tempPosX = posX;
	int tempPosY = posY;

	// 將每一小幅圖像整合成大圖像
	for (int i = 0; i < nNumImages; i++)
	{
		// 小圖像坐標轉換
		if((i % nSizeWindows.width == 0) && (tempPosX != posX))
		{
			tempPosX = posX;
			tempPosY += (nSplitLineSize + nShowImageSize);
		}

		// 利用Rect區域將小圖像置於大圖像相應區域
		cv::Mat tempImage = showWindowImages(cv::Rect(tempPosX, tempPosY, nShowImageSize, nShowImageSize));

		//利用resize函數實現圖像縮放
		resize(srcImages[i], tempImage, cv::Size(nShowImageSize, nShowImageSize));
		tempPosX += (nSplitLineSize + nShowImageSize);
	}
	
	cv::imshow("showWindowImages", showWindowImages);
}

int main()
{
	// 圖像源輸入
	std::vector<cv::Mat> srcImages(9);
	srcImages[0] = cv::imread("a.jpg");
	srcImages[1] = cv::imread("a.jpg");
	srcImages[2] = cv::imread("a.jpg");
	srcImages[3] = cv::imread("a.jpg");
	srcImages[4] = cv::imread("a.jpg");
	srcImages[5] = cv::imread("a.jpg");
	srcImages[6] = cv::imread("a.jpg");
	srcImages[7] = cv::imread("a.jpg");
	srcImages[8] = cv::imread("a.jpg");
	
	// 判斷當前vector讀入的正確性
	for (int i = 0; i < srcImages.size(); i++)
	{
		if (!srcImages[i].data)
		{
			std::cout << "read error!" << std::endl;
			return -1;
		}
	}

	//調用單窗口顯示圖像
	showManyImages(srcImages, cv::Size(512, 400));
	cv::waitKey(0);
	return 0;
}