OpenCV 批量加倾斜透明水印

帮同事实现了个批量加倾斜透明水印的功能，代码整理了下，供大家参考。

实现的功能：

1. 单个水印

通过putText函数或自定义的putTextHuskyC函数；

2. 批量水印

通过vconcat 纵向拼接及hconcat横向拼接；

3. 透明水印

通过addWeighted函数；

4. 批量倾斜透明水印

通过getRotationMatrix2D和warpAffine函数；

以下为具体实现：

1. 单个水印

因为cv::putText函数不能方便地绘制中文和宋体、楷体和Times New Roman等字体，采用以下代码可方便地进行文字在图像上居中绘制。

#include <windows.h>
#include <opencv2/opencv.hpp>

// 计算str字符串尺寸
void GetStringSize(HDC hDC, const char* str, int* w, int* h)
{
	SIZE size;
	GetTextExtentPoint32A(hDC, str, strlen(str), &size);
	if (w != 0) *w = size.cx;
	if (h != 0) *h = size.cy;
}

//color颜色，fontSize字号，fn字体
//italic斜体，underline下划线
void putTextHuskyC(cv::Mat& dst, const char* str, cv::Scalar color, int fontSize, const char* fn, bool italic, bool underline)
{
	CV_Assert(dst.data != 0 && (dst.channels() == 1 || dst.channels() == 3));

	int x, y, r, b;

	x = 0;
	y = 0;

	LOGFONTA lf;
	lf.lfHeight = -fontSize;
	lf.lfWidth = 0;
	lf.lfEscapement = 0;
	lf.lfOrientation = 0;
	lf.lfWeight = 5;
	lf.lfItalic = italic;   //斜体
	lf.lfUnderline = underline; //下划线
	lf.lfStrikeOut = 0;
	lf.lfCharSet = DEFAULT_CHARSET;
	lf.lfOutPrecision = 0;
	lf.lfClipPrecision = 0;
	lf.lfQuality = PROOF_QUALITY;
	lf.lfPitchAndFamily = 0;
	strcpy_s(lf.lfFaceName, fn);

	HFONT hf = CreateFontIndirectA(&lf);
	HDC hDC = CreateCompatibleDC(0);
	HFONT hOldFont = (HFONT)SelectObject(hDC, hf);

	int strBaseW = 0, strBaseH = 0;
	int singleRow = 0;
	char buf[1 << 12];
	strcpy_s(buf, str);
	char* bufT[1 << 12];  // 这个用于分隔字符串后剩余的字符，可能会超出。
	int nnh = 0;
	int cw, ch;

	const char* ln = strtok_s(buf, "\n", bufT);
	while (ln != 0)
	{
		GetStringSize(hDC, ln, &cw, &ch);
		strBaseW = max(strBaseW, cw);
		strBaseH = max(strBaseH, ch);

		ln = strtok_s(0, "\n", bufT);
		nnh++;
	}
	singleRow = strBaseH;
	strBaseH *= nnh;

	int orgX = dst.cols / 2 - strBaseW / 2;
	int orgY = dst.rows / 2 - strBaseH / 2;
	r = orgX + strBaseW > dst.cols ? dst.cols - orgX - 1 : strBaseW - 1;
	b = orgY + strBaseH > dst.rows ? dst.rows - orgY - 1 : strBaseH - 1;
	orgX = orgX < 0 ? 0 : orgX;
	orgY = orgY < 0 ? 0 : orgY;

	BITMAPINFO bmp = { 0 };
	BITMAPINFOHEADER& bih = bmp.bmiHeader;
	int strDrawLineStep = strBaseW * 3 % 4 == 0 ? strBaseW * 3 : (strBaseW * 3 + 4 - ((strBaseW * 3) % 4));

	bih.biSize = sizeof(BITMAPINFOHEADER);
	bih.biWidth = strBaseW;
	bih.biHeight = strBaseH;
	bih.biPlanes = 1;
	bih.biBitCount = 24;
	bih.biCompression = BI_RGB;
	bih.biSizeImage = strBaseH * strDrawLineStep;
	bih.biClrUsed = 0;
	bih.biClrImportant = 0;

	void* pDibData = 0;
	HBITMAP hBmp = CreateDIBSection(hDC, &bmp, DIB_RGB_COLORS, &pDibData, 0, 0);

	CV_Assert(pDibData != 0);
	HBITMAP hOldBmp = (HBITMAP)SelectObject(hDC, hBmp);

	SetTextColor(hDC, RGB(255, 255, 255));
	SetBkColor(hDC, 0);

	strcpy_s(buf, str);
	ln = strtok_s(buf, "\n", bufT);
	int outTextY = 0;
	while (ln != 0)
	{
		TextOutA(hDC, 0, outTextY, ln, strlen(ln));
		outTextY += singleRow;
		ln = strtok_s(0, "\n", bufT);
	}
	uchar* dstData = (uchar*)dst.data;
	int dstStep = dst.step / sizeof(dstData[0]);
	unsigned char* pImg = (unsigned char*)dst.data + orgX * dst.channels() + orgY * dstStep;
	unsigned char* pStr = (unsigned char*)pDibData + x * 3;
	for (int tty = y; tty <= b; ++tty)
	{
		unsigned char* subImg = pImg + (tty - y) * dstStep;
		unsigned char* subStr = pStr + (strBaseH - tty - 1) * strDrawLineStep;
		for (int ttx = x; ttx <= r; ++ttx)
		{
			for (int n = 0; n < dst.channels(); ++n) {
				double vtxt = subStr[n] / 255.0;
				int cvv = vtxt * color.val[n] + (1 - vtxt) * subImg[n];
				subImg[n] = cvv > 255 ? 255 : (cvv < 0 ? 0 : cvv);
			}

			subStr += 3;
			subImg += dst.channels();
		}
	}

	SelectObject(hDC, hOldBmp);
	SelectObject(hDC, hOldFont);
	DeleteObject(hf);
	DeleteObject(hBmp);
	DeleteDC(hDC);
}

执行以下代码

cv::Mat singleWatermark = cv::Mat::zeros(cv::Size(320, 135), CV_8UC3);
std::string text = "watermark_2023_04_17";
putTextHuskyC(singleWatermark, text.c_str(), cv::Scalar(255, 255, 255), 24, "Times New Roman", false, false);

得到如下单个水印图

 2. 批量透明水印

cv::Mat srcImage = cv::imread("ai_beauty.jpg");
if (srcImage.empty())
{
	std::cout << "输入图像为空" << std::endl;
	return;
}

// 重复小图成大图
int hRepeat = 3;	// 横向重复次数
int vRepeat = 4;	// 纵向重复次数

vector<cv::Mat> vImgs;
cv::Mat vResult;
for (int vi = 0; vi < vRepeat; vi++)
	vImgs.push_back(singleWatermark);
vconcat(vImgs, vResult); //纵向拼接

vector<cv::Mat> hImgs;
cv::Mat hResult;
for (int hi = 0; hi < hRepeat; hi++)
	hImgs.push_back(vResult);
hconcat(hImgs, hResult); //横向拼接

// 最终水印图
cv::Mat finalWatermark = hResult;

cv::Mat imageROI;
imageROI = srcImage(cv::Rect(0, 0, finalWatermark.cols, finalWatermark.rows));
cv::addWeighted(imageROI, 1.0, finalWatermark, 0.3, 0, imageROI);
cv::imshow("final watermark", srcImage);
cv::waitKey(0);

3. 批量倾斜透明水印

// 重复小图成大图
int hRepeat = 5;	// 横向重复次数
int vRepeat = 8;	// 纵向重复次数

vector<cv::Mat> vImgs;
cv::Mat vResult;
for (int vi = 0; vi < vRepeat; vi++)
	vImgs.push_back(singleWatermark);
vconcat(vImgs, vResult); //纵向拼接

vector<cv::Mat> hImgs;
cv::Mat hResult;
for (int hi = 0; hi < hRepeat; hi++)
	hImgs.push_back(vResult);
hconcat(hImgs, hResult); //横向拼接

// 旋转图像
double angle = 45;  // 水印逆时针旋转角度
cv::Point2f center(hResult.cols / 2.0, hResult.rows / 2.0);
cv::Mat rotation_matix = getRotationMatrix2D(center, angle, 1.0);
cv::Mat rotated_image;
cv::warpAffine(hResult, rotated_image, rotation_matix, hResult.size());

// 最终水印图
cv::Mat finalWatermark = rotated_image(cv::Rect((hResult.cols - imageWidth) / 2, (hResult.rows - imageHeight) / 2, imageWidth, imageHeight));

// OpenCV加水印
cv::Mat imageROI;
imageROI = srcImage(cv::Rect(0, 0, finalWatermark.cols, finalWatermark.rows));
cv::addWeighted(imageROI, 1.0, finalWatermark, 0.3, 0, imageROI);
cv::imshow("final watermark", srcImage);
cv::waitKey(0);