OpenCV中resize函数插值算法的实现过程(五种)


Posted in Python onJune 05, 2021

最新版OpenCV2.4.7中,cv::resize函数有五种插值算法:最近邻、双线性、双三次、基于像素区域关系、兰索斯插值。下面用for循环代替cv::resize函数来说明其详细的插值实现过程,其中部分代码摘自于cv::resize函数中的源代码。

每种插值算法的前部分代码是相同的,如下:

cv::Mat matSrc, matDst1, matDst2;
 
	matSrc = cv::imread("lena.jpg", 2 | 4);
	matDst1 = cv::Mat(cv::Size(800, 1000), matSrc.type(), cv::Scalar::all(0));
	matDst2 = cv::Mat(matDst1.size(), matSrc.type(), cv::Scalar::all(0));
 
	double scale_x = (double)matSrc.cols / matDst1.cols;
	double scale_y = (double)matSrc.rows / matDst1.rows;

1、最近邻:公式,

OpenCV中resize函数插值算法的实现过程(五种)

for (int i = 0; i < matDst1.cols; ++i)
	{
		int sx = cvFloor(i * scale_x);
		sx = std::min(sx, matSrc.cols - 1);
		for (int j = 0; j < matDst1.rows; ++j)
		{
			int sy = cvFloor(j * scale_y);
			sy = std::min(sy, matSrc.rows - 1);
			matDst1.at<cv::Vec3b>(j, i) = matSrc.at<cv::Vec3b>(sy, sx);
		}
	}
	cv::imwrite("nearest_1.jpg", matDst1);
 
	cv::resize(matSrc, matDst2, matDst1.size(), 0, 0, 0);
	cv::imwrite("nearest_2.jpg", matDst2);

2、双线性:由相邻的四像素(2*2)计算得出,公式,

OpenCV中resize函数插值算法的实现过程(五种)

uchar* dataDst = matDst1.data;
	int stepDst = matDst1.step;
	uchar* dataSrc = matSrc.data;
	int stepSrc = matSrc.step;
	int iWidthSrc = matSrc.cols;
	int iHiehgtSrc = matSrc.rows;
 
	for (int j = 0; j < matDst1.rows; ++j)
	{
		float fy = (float)((j + 0.5) * scale_y - 0.5);
		int sy = cvFloor(fy);
		fy -= sy;
		sy = std::min(sy, iHiehgtSrc - 2);
		sy = std::max(0, sy);
 
		short cbufy[2];
		cbufy[0] = cv::saturate_cast<short>((1.f - fy) * 2048);
		cbufy[1] = 2048 - cbufy[0];
 
		for (int i = 0; i < matDst1.cols; ++i)
		{
			float fx = (float)((i + 0.5) * scale_x - 0.5);
			int sx = cvFloor(fx);
			fx -= sx;
 
			if (sx < 0) {
				fx = 0, sx = 0;
			}
			if (sx >= iWidthSrc - 1) {
				fx = 0, sx = iWidthSrc - 2;
			}
 
			short cbufx[2];
			cbufx[0] = cv::saturate_cast<short>((1.f - fx) * 2048);
			cbufx[1] = 2048 - cbufx[0];
 
			for (int k = 0; k < matSrc.channels(); ++k)
			{
				*(dataDst+ j*stepDst + 3*i + k) = (*(dataSrc + sy*stepSrc + 3*sx + k) * cbufx[0] * cbufy[0] + 
					*(dataSrc + (sy+1)*stepSrc + 3*sx + k) * cbufx[0] * cbufy[1] + 
					*(dataSrc + sy*stepSrc + 3*(sx+1) + k) * cbufx[1] * cbufy[0] + 
					*(dataSrc + (sy+1)*stepSrc + 3*(sx+1) + k) * cbufx[1] * cbufy[1]) >> 22;
			}
		}
	}
	cv::imwrite("linear_1.jpg", matDst1);
 
	cv::resize(matSrc, matDst2, matDst1.size(), 0, 0, 1);
	cv::imwrite("linear_2.jpg", matDst2);

3、双三次:由相邻的4*4像素计算得出,公式类似于双线性

int iscale_x = cv::saturate_cast<int>(scale_x);
	int iscale_y = cv::saturate_cast<int>(scale_y);
 
	for (int j = 0; j < matDst1.rows; ++j)
	{
		float fy = (float)((j + 0.5) * scale_y - 0.5);
		int sy = cvFloor(fy);
		fy -= sy;
		sy = std::min(sy, matSrc.rows - 3);
		sy = std::max(1, sy);
 
		const float A = -0.75f;
 
		float coeffsY[4];
		coeffsY[0] = ((A*(fy + 1) - 5*A)*(fy + 1) + 8*A)*(fy + 1) - 4*A;
		coeffsY[1] = ((A + 2)*fy - (A + 3))*fy*fy + 1;
		coeffsY[2] = ((A + 2)*(1 - fy) - (A + 3))*(1 - fy)*(1 - fy) + 1;
		coeffsY[3] = 1.f - coeffsY[0] - coeffsY[1] - coeffsY[2];
 
		short cbufY[4];
		cbufY[0] = cv::saturate_cast<short>(coeffsY[0] * 2048);
		cbufY[1] = cv::saturate_cast<short>(coeffsY[1] * 2048);
		cbufY[2] = cv::saturate_cast<short>(coeffsY[2] * 2048);
		cbufY[3] = cv::saturate_cast<short>(coeffsY[3] * 2048);
 
		for (int i = 0; i < matDst1.cols; ++i)
		{
			float fx = (float)((i + 0.5) * scale_x - 0.5);
			int sx = cvFloor(fx);
			fx -= sx;
 
			if (sx < 1) {
				fx = 0, sx = 1;
			}
			if (sx >= matSrc.cols - 3) {
				fx = 0, sx = matSrc.cols - 3;
			}
 
			float coeffsX[4];
			coeffsX[0] = ((A*(fx + 1) - 5*A)*(fx + 1) + 8*A)*(fx + 1) - 4*A;
			coeffsX[1] = ((A + 2)*fx - (A + 3))*fx*fx + 1;
			coeffsX[2] = ((A + 2)*(1 - fx) - (A + 3))*(1 - fx)*(1 - fx) + 1;
			coeffsX[3] = 1.f - coeffsX[0] - coeffsX[1] - coeffsX[2];
 
			short cbufX[4];
			cbufX[0] = cv::saturate_cast<short>(coeffsX[0] * 2048);
			cbufX[1] = cv::saturate_cast<short>(coeffsX[1] * 2048);
			cbufX[2] = cv::saturate_cast<short>(coeffsX[2] * 2048);
			cbufX[3] = cv::saturate_cast<short>(coeffsX[3] * 2048);
 
			for (int k = 0; k < matSrc.channels(); ++k)
			{
				matDst1.at<cv::Vec3b>(j, i)[k] = abs((matSrc.at<cv::Vec3b>(sy-1, sx-1)[k] * cbufX[0] * cbufY[0] + matSrc.at<cv::Vec3b>(sy, sx-1)[k] * cbufX[0] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy+1, sx-1)[k] * cbufX[0] * cbufY[2] + matSrc.at<cv::Vec3b>(sy+2, sx-1)[k] * cbufX[0] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy-1, sx)[k] * cbufX[1] * cbufY[0] + matSrc.at<cv::Vec3b>(sy, sx)[k] * cbufX[1] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy+1, sx)[k] * cbufX[1] * cbufY[2] + matSrc.at<cv::Vec3b>(sy+2, sx)[k] * cbufX[1] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy-1, sx+1)[k] * cbufX[2] * cbufY[0] + matSrc.at<cv::Vec3b>(sy, sx+1)[k] * cbufX[2] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy+1, sx+1)[k] * cbufX[2] * cbufY[2] + matSrc.at<cv::Vec3b>(sy+2, sx+1)[k] * cbufX[2] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy-1, sx+2)[k] * cbufX[3] * cbufY[0] + matSrc.at<cv::Vec3b>(sy, sx+2)[k] * cbufX[3] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy+1, sx+2)[k] * cbufX[3] * cbufY[2] + matSrc.at<cv::Vec3b>(sy+2, sx+2)[k] * cbufX[3] * cbufY[3] ) >> 22);
			}
		}
	}
	cv::imwrite("cubic_1.jpg", matDst1);
 
	cv::resize(matSrc, matDst2, matDst1.size(), 0, 0, 2);
	cv::imwrite("cubic_2.jpg", matDst2);

4、基于像素区域关系:共分三种情况,图像放大时类似于双线性插值,图像缩小(x轴、y轴同时缩小)又分两种情况,此情况下可以避免波纹出现。

#ifdef _MSC_VER
	cv::resize(matSrc, matDst2, matDst1.size(), 0, 0, 3);
	cv::imwrite("E:/GitCode/OpenCV_Test/test_images/area_2.jpg", matDst2);
#else
	cv::resize(matSrc, matDst2, matDst1.size(), 0, 0, 3);
	cv::imwrite("area_2.jpg", matDst2);
#endif
 
	fprintf(stdout, "==== start area ====\n");
	double inv_scale_x = 1. / scale_x;
	double inv_scale_y = 1. / scale_y;
	int iscale_x = cv::saturate_cast<int>(scale_x);
	int iscale_y = cv::saturate_cast<int>(scale_y);
	bool is_area_fast = std::abs(scale_x - iscale_x) < DBL_EPSILON && std::abs(scale_y - iscale_y) < DBL_EPSILON;
 
	if (scale_x >= 1 && scale_y >= 1)  { // zoom out
		if (is_area_fast)  { // integer multiples
			for (int j = 0; j < matDst1.rows; ++j) {
				int sy = std::min(cvFloor(j * scale_y), matSrc.rows - 1);
 
				for (int i = 0; i < matDst1.cols; ++i) {
					int sx = std::min(cvFloor(i * scale_x), matSrc.cols -1);
 
					matDst1.at<cv::Vec3b>(j, i) = matSrc.at<cv::Vec3b>(sy, sx);
				}
			}
#ifdef _MSC_VER
			cv::imwrite("E:/GitCode/OpenCV_Test/test_images/area_1.jpg", matDst1);
#else
			cv::imwrite("area_1.jpg", matDst1);
#endif
			return 0;
		}
 
		for (int j = 0; j < matDst1.rows; ++j) {
			double fsy1 = j * scale_y;
			double fsy2 = fsy1 + scale_y;
			double cellHeight = cv::min(scale_y, matSrc.rows - fsy1);
 
			int sy1 = cvCeil(fsy1), sy2 = cvFloor(fsy2);
 
			sy2 = std::min(sy2, matSrc.rows - 2);
			sy1 = std::min(sy1, sy2);
 
			float cbufy[2];
			cbufy[0] = (float)((sy1 - fsy1) / cellHeight);
			cbufy[1] = (float)(std::min(std::min(fsy2 - sy2, 1.), cellHeight) / cellHeight);
 
			for (int i = 0; i < matDst1.cols; ++i) {
				double fsx1 = i * scale_x;
				double fsx2 = fsx1 + scale_x;
				double cellWidth = std::min(scale_x, matSrc.cols - fsx1);
 
				int sx1 = cvCeil(fsx1), sx2 = cvFloor(fsx2);
 
				sx2 = std::min(sx2, matSrc.cols - 2);
				sx1 = std::min(sx1, sx2);
 
				float cbufx[2];
				cbufx[0] = (float)((sx1 - fsx1) / cellWidth);
				cbufx[1] = (float)(std::min(std::min(fsx2 - sx2, 1.), cellWidth) / cellWidth);
 
				for (int k = 0; k < matSrc.channels(); ++k) {
					matDst1.at<cv::Vec3b>(j, i)[k] = (uchar)(matSrc.at<cv::Vec3b>(sy1, sx1)[k] * cbufx[0] * cbufy[0] +
						matSrc.at<cv::Vec3b>(sy1 + 1, sx1)[k] * cbufx[0] * cbufy[1] +
						matSrc.at<cv::Vec3b>(sy1, sx1 + 1)[k] * cbufx[1] * cbufy[0] +
						matSrc.at<cv::Vec3b>(sy1 + 1, sx1 + 1)[k] * cbufx[1] * cbufy[1]);
				}
			}
		}
#ifdef _MSC_VER
		cv::imwrite("E:/GitCode/OpenCV_Test/test_images/area_1.jpg", matDst1);
#else
		cv::imwrite("area_1.jpg", matDst1);
#endif
 
		return 0;
	}
 
	//zoom in,it is emulated using some variant of bilinear interpolation
	for (int j = 0; j < matDst1.rows; ++j) {
		int  sy = cvFloor(j * scale_y);
		float fy = (float)((j + 1) - (sy + 1) * inv_scale_y);
		fy = fy <= 0 ? 0.f : fy - cvFloor(fy);
		sy = std::min(sy, matSrc.rows - 2);
 
		short cbufy[2];
		cbufy[0] = cv::saturate_cast<short>((1.f - fy) * 2048);
		cbufy[1] = 2048 - cbufy[0];
 
		for (int i = 0; i < matDst1.cols; ++i) {
			int sx = cvFloor(i * scale_x);
			float fx = (float)((i + 1) - (sx + 1) * inv_scale_x);
			fx = fx < 0 ? 0.f : fx - cvFloor(fx);
 
			if (sx < 0) {
				fx = 0, sx = 0;
			}
 
			if (sx >= matSrc.cols - 1) {
				fx = 0, sx = matSrc.cols - 2;
			}
 
			short cbufx[2];
			cbufx[0] = cv::saturate_cast<short>((1.f - fx) * 2048);
			cbufx[1] = 2048 - cbufx[0];
 
			for (int k = 0; k < matSrc.channels(); ++k) {
				matDst1.at<cv::Vec3b>(j, i)[k] = (matSrc.at<cv::Vec3b>(sy, sx)[k] * cbufx[0] * cbufy[0] +
					matSrc.at<cv::Vec3b>(sy + 1, sx)[k] * cbufx[0] * cbufy[1] +
					matSrc.at<cv::Vec3b>(sy, sx + 1)[k] * cbufx[1] * cbufy[0] +
					matSrc.at<cv::Vec3b>(sy + 1, sx + 1)[k] * cbufx[1] * cbufy[1]) >> 22;
			}
		}
	}
	fprintf(stdout, "==== end area ====\n");
 
#ifdef _MSC_VER
	cv::imwrite("E:/GitCode/OpenCV_Test/test_images/area_1.jpg", matDst1);
#else
	cv::imwrite("area_1.jpg", matDst1);
#endif

注:以上基于area进行图像缩小的代码有问题,具体实现代码可以参考https://github.com/fengbingchun/OpenCV_Test/blob/master/src/fbc_cv/include/resize.hpp,用法如下:

fbc::Mat3BGR src(matSrc.rows, matSrc.cols, matSrc.data);
fbc::Mat3BGR dst(matDst1.rows, matDst1.cols, matDst1.data);
fbc::resize(src, dst, 3);

5、兰索斯插值:由相邻的8*8像素计算得出,公式类似于双线性

int iscale_x = cv::saturate_cast<int>(scale_x);
	int iscale_y = cv::saturate_cast<int>(scale_y);
 
	for (int j = 0; j < matDst1.rows; ++j)
	{
		float fy = (float)((j + 0.5) * scale_y - 0.5);
		int sy = cvFloor(fy);
		fy -= sy;
		sy = std::min(sy, matSrc.rows - 5);
		sy = std::max(3, sy);
 
		const double s45 = 0.70710678118654752440084436210485;
		const double cs[][2] = {{1, 0}, {-s45, -s45}, {0, 1}, {s45, -s45}, {-1, 0}, {s45, s45}, {0, -1}, {-s45, s45}};
		float coeffsY[8];
 
		if (fy < FLT_EPSILON) {
			for (int t = 0; t < 8; t++)
				coeffsY[t] = 0;
			coeffsY[3] = 1;
		} else {
			float sum = 0;
			double y0 = -(fy + 3) * CV_PI * 0.25, s0 = sin(y0), c0 = cos(y0);
 
			for (int t = 0; t < 8; ++t)
			{
				double dy = -(fy + 3 -t) * CV_PI * 0.25;
				coeffsY[t] = (float)((cs[t][0] * s0 + cs[t][1] * c0) / (dy * dy));
				sum += coeffsY[t];
			}
 
			sum = 1.f / sum;
			for (int t = 0; t < 8; ++t)
				coeffsY[t] *= sum;
		}
 
		short cbufY[8];
		cbufY[0] = cv::saturate_cast<short>(coeffsY[0] * 2048);
		cbufY[1] = cv::saturate_cast<short>(coeffsY[1] * 2048);
		cbufY[2] = cv::saturate_cast<short>(coeffsY[2] * 2048);
		cbufY[3] = cv::saturate_cast<short>(coeffsY[3] * 2048);
		cbufY[4] = cv::saturate_cast<short>(coeffsY[4] * 2048);
		cbufY[5] = cv::saturate_cast<short>(coeffsY[5] * 2048);
		cbufY[6] = cv::saturate_cast<short>(coeffsY[6] * 2048);
		cbufY[7] = cv::saturate_cast<short>(coeffsY[7] * 2048);
 
		for (int i = 0; i < matDst1.cols; ++i)
		{
			float fx = (float)((i + 0.5) * scale_x - 0.5);
			int sx = cvFloor(fx);
			fx -= sx;
 
			if (sx < 3) {
				fx = 0, sx = 3;
			}
			if (sx >= matSrc.cols - 5) {
				fx = 0, sx = matSrc.cols - 5;
			}
 
			float coeffsX[8];
 
			if (fx < FLT_EPSILON) {
				for ( int t = 0; t < 8; t++ )
					coeffsX[t] = 0;
				coeffsX[3] = 1;
			} else {
				float sum = 0;
				double x0 = -(fx + 3) * CV_PI * 0.25, s0 = sin(x0), c0 = cos(x0);
 
				for (int t = 0; t < 8; ++t)
				{
					double dx = -(fx + 3 -t) * CV_PI * 0.25;
					coeffsX[t] = (float)((cs[t][0] * s0 + cs[t][1] * c0) / (dx * dx));
					sum += coeffsX[t];
				}
 
				sum = 1.f / sum;
				for (int t = 0; t < 8; ++t)
					coeffsX[t] *= sum;
			}
 
			short cbufX[8];
			cbufX[0] = cv::saturate_cast<short>(coeffsX[0] * 2048);
			cbufX[1] = cv::saturate_cast<short>(coeffsX[1] * 2048);
			cbufX[2] = cv::saturate_cast<short>(coeffsX[2] * 2048);
			cbufX[3] = cv::saturate_cast<short>(coeffsX[3] * 2048);
			cbufX[4] = cv::saturate_cast<short>(coeffsX[4] * 2048);
			cbufX[5] = cv::saturate_cast<short>(coeffsX[5] * 2048);
			cbufX[6] = cv::saturate_cast<short>(coeffsX[6] * 2048);
			cbufX[7] = cv::saturate_cast<short>(coeffsX[7] * 2048);
 
			for (int k = 0; k < matSrc.channels(); ++k)
			{
				matDst1.at<cv::Vec3b>(j, i)[k] = abs((matSrc.at<cv::Vec3b>(sy-3, sx-3)[k] * cbufX[0] * cbufY[0] + matSrc.at<cv::Vec3b>(sy-2, sx-3)[k] * cbufX[0] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy-1, sx-3)[k] * cbufX[0] * cbufY[2] + matSrc.at<cv::Vec3b>(sy, sx-3)[k] * cbufX[0] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy+1, sx-3)[k] * cbufX[0] * cbufY[4] + matSrc.at<cv::Vec3b>(sy+2, sx-3)[k] * cbufX[0] * cbufY[5] +
					matSrc.at<cv::Vec3b>(sy+3, sx-3)[k] * cbufX[0] * cbufY[6] + matSrc.at<cv::Vec3b>(sy+4, sx-3)[k] * cbufX[0] * cbufY[7] +
 
					matSrc.at<cv::Vec3b>(sy-3, sx-2)[k] * cbufX[1] * cbufY[0] + matSrc.at<cv::Vec3b>(sy-2, sx-2)[k] * cbufX[1] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy-1, sx-2)[k] * cbufX[1] * cbufY[2] + matSrc.at<cv::Vec3b>(sy, sx-2)[k] * cbufX[1] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy+1, sx-2)[k] * cbufX[1] * cbufY[4] + matSrc.at<cv::Vec3b>(sy+2, sx-2)[k] * cbufX[1] * cbufY[5] +
					matSrc.at<cv::Vec3b>(sy+3, sx-2)[k] * cbufX[1] * cbufY[6] + matSrc.at<cv::Vec3b>(sy+4, sx-2)[k] * cbufX[1] * cbufY[7] +
 
					matSrc.at<cv::Vec3b>(sy-3, sx-1)[k] * cbufX[2] * cbufY[0] + matSrc.at<cv::Vec3b>(sy-2, sx-1)[k] * cbufX[2] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy-1, sx-1)[k] * cbufX[2] * cbufY[2] + matSrc.at<cv::Vec3b>(sy, sx-1)[k] * cbufX[2] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy+1, sx-1)[k] * cbufX[2] * cbufY[4] + matSrc.at<cv::Vec3b>(sy+2, sx-1)[k] * cbufX[2] * cbufY[5] +
					matSrc.at<cv::Vec3b>(sy+3, sx-1)[k] * cbufX[2] * cbufY[6] + matSrc.at<cv::Vec3b>(sy+4, sx-1)[k] * cbufX[2] * cbufY[7] +
 
					matSrc.at<cv::Vec3b>(sy-3, sx)[k] * cbufX[3] * cbufY[0] + matSrc.at<cv::Vec3b>(sy-2, sx)[k] * cbufX[3] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy-1, sx)[k] * cbufX[3] * cbufY[2] + matSrc.at<cv::Vec3b>(sy, sx)[k] * cbufX[3] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy+1, sx)[k] * cbufX[3] * cbufY[4] + matSrc.at<cv::Vec3b>(sy+2, sx)[k] * cbufX[3] * cbufY[5] +
					matSrc.at<cv::Vec3b>(sy+3, sx)[k] * cbufX[3] * cbufY[6] + matSrc.at<cv::Vec3b>(sy+4, sx)[k] * cbufX[3] * cbufY[7] +
 
					matSrc.at<cv::Vec3b>(sy-3, sx+1)[k] * cbufX[4] * cbufY[0] + matSrc.at<cv::Vec3b>(sy-2, sx+1)[k] * cbufX[4] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy-1, sx+1)[k] * cbufX[4] * cbufY[2] + matSrc.at<cv::Vec3b>(sy, sx+1)[k] * cbufX[4] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy+1, sx+1)[k] * cbufX[4] * cbufY[4] + matSrc.at<cv::Vec3b>(sy+2, sx+1)[k] * cbufX[4] * cbufY[5] +
					matSrc.at<cv::Vec3b>(sy+3, sx+1)[k] * cbufX[4] * cbufY[6] + matSrc.at<cv::Vec3b>(sy+4, sx+1)[k] * cbufX[4] * cbufY[7] +
 
					matSrc.at<cv::Vec3b>(sy-3, sx+2)[k] * cbufX[5] * cbufY[0] + matSrc.at<cv::Vec3b>(sy-2, sx+2)[k] * cbufX[5] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy-1, sx+2)[k] * cbufX[5] * cbufY[2] + matSrc.at<cv::Vec3b>(sy, sx+2)[k] * cbufX[5] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy+1, sx+2)[k] * cbufX[5] * cbufY[4] + matSrc.at<cv::Vec3b>(sy+2, sx+2)[k] * cbufX[5] * cbufY[5] +
					matSrc.at<cv::Vec3b>(sy+3, sx+2)[k] * cbufX[5] * cbufY[6] + matSrc.at<cv::Vec3b>(sy+4, sx+2)[k] * cbufX[5] * cbufY[7] +
 
					matSrc.at<cv::Vec3b>(sy-3, sx+3)[k] * cbufX[6] * cbufY[0] + matSrc.at<cv::Vec3b>(sy-2, sx+3)[k] * cbufX[6] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy-1, sx+3)[k] * cbufX[6] * cbufY[2] + matSrc.at<cv::Vec3b>(sy, sx+3)[k] * cbufX[6] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy+1, sx+3)[k] * cbufX[6] * cbufY[4] + matSrc.at<cv::Vec3b>(sy+2, sx+3)[k] * cbufX[6] * cbufY[5] +
					matSrc.at<cv::Vec3b>(sy+3, sx+3)[k] * cbufX[6] * cbufY[6] + matSrc.at<cv::Vec3b>(sy+4, sx+3)[k] * cbufX[6] * cbufY[7] +
 
					matSrc.at<cv::Vec3b>(sy-3, sx+4)[k] * cbufX[7] * cbufY[0] + matSrc.at<cv::Vec3b>(sy-2, sx+4)[k] * cbufX[7] * cbufY[1] +
					matSrc.at<cv::Vec3b>(sy-1, sx+4)[k] * cbufX[7] * cbufY[2] + matSrc.at<cv::Vec3b>(sy, sx+4)[k] * cbufX[7] * cbufY[3] +
					matSrc.at<cv::Vec3b>(sy+1, sx+4)[k] * cbufX[7] * cbufY[4] + matSrc.at<cv::Vec3b>(sy+2, sx+4)[k] * cbufX[7] * cbufY[5] +
					matSrc.at<cv::Vec3b>(sy+3, sx+4)[k] * cbufX[7] * cbufY[6] + matSrc.at<cv::Vec3b>(sy+4, sx+4)[k] * cbufX[7] * cbufY[7] ) >> 22);// 4194304
			}
		}
	}
	cv::imwrite("Lanczos_1.jpg", matDst1);
 
	cv::resize(matSrc, matDst2, matDst1.size(), 0, 0, 4);
	cv::imwrite("Lanczos_2.jpg", matDst2);

以上代码的实现结果与cv::resize函数相同,但是执行效率非常低,只是为了详细说明插值过程。OpenCV中默认采用C++ Concurrency进行优化加速,你也可以采用TBB、OpenMP等进行优化加速。

GitHubhttps://github.com/fengbingchun/OpenCV_Test/blob/master/demo/OpenCV_Test/test_opencv_funset.cpp

到此这篇关于OpenCV中resize函数插值算法的实现过程(五种)的文章就介绍到这了,更多相关OpenCV resize插值内容请搜索三水点靠木以前的文章或继续浏览下面的相关文章希望大家以后多多支持三水点靠木!

Python 相关文章推荐
使用Python的Flask框架实现视频的流媒体传输
Mar 31 Python
python爬虫实战之最简单的网页爬虫教程
Aug 13 Python
python中format()函数的简单使用教程
Mar 14 Python
python判断输入日期为第几天的实例
Nov 13 Python
django框架单表操作之增删改实例分析
Dec 16 Python
Windows系统下pycharm中的pip换源
Feb 23 Python
Python基础之字符串常见操作经典实例详解
Feb 26 Python
pytorch之Resize()函数具体使用详解
Feb 27 Python
常用的10个Python实用小技巧
Aug 10 Python
python对批量WAV音频进行等长分割的方法实现
Sep 25 Python
如何用tempfile库创建python进程中的临时文件
Jan 28 Python
Python实现科学占卜 让视频自动打码
Apr 09 Python
OpenCV全景图像拼接的实现示例
opencv 分类白天与夜景视频的方法
python如何利用traceback获取详细的异常信息
Jun 05 #Python
Python异常类型以及处理方法汇总
Jun 05 #Python
Python OpenCV 彩色与灰度图像的转换实现
Python深度学习之实现卷积神经网络
python opencv通过4坐标剪裁图片
Jun 05 #Python
You might like
php Undefined index和Undefined variable的解决方法
2008/03/27 PHP
理解php原理的opcodes(操作码)
2010/10/26 PHP
php基于dom实现读取图书xml格式数据的方法
2017/02/03 PHP
Thinkphp整合阿里云OSS图片上传实例代码
2019/04/28 PHP
一行代码告别document.getElementById
2012/06/01 Javascript
javascript eval(func())使用示例
2013/12/05 Javascript
基于Bootstrap+jQuery.validate实现Form表单验证
2014/12/16 Javascript
jquery让指定的元素闪烁显示的方法
2015/03/17 Javascript
仿Angular Bootstrap TimePicker创建分钟数-秒数的输入控件
2016/07/01 Javascript
jQuery组件easyui对话框实现代码
2016/08/25 Javascript
根据Bootstrap Paginator改写的js分页插件
2016/12/25 Javascript
Vue插件写、用详解(附demo)
2017/03/20 Javascript
JavaScript实现前端分页控件
2017/04/19 Javascript
使用微信小程序开发弹出框应用实例详解
2018/10/18 Javascript
Vue 使用计时器实现跑马灯效果的实例代码
2019/07/11 Javascript
JS获取动态添加元素的方法详解
2019/07/31 Javascript
微信小程序实现蓝牙打印
2019/09/23 Javascript
Vue中函数防抖节流的理解及应用实现
2020/04/24 Javascript
ant design的table组件实现全选功能以及自定义分页
2020/11/17 Javascript
jQuery实现容器间的元素拖拽功能
2020/12/01 jQuery
python装饰器使用方法实例
2013/11/21 Python
Django学习笔记之Class-Based-View
2017/02/15 Python
在matplotlib的图中设置中文标签的方法
2018/12/13 Python
PyCharm中配置PySide2的图文教程
2020/06/18 Python
python把一个字符串切开的实例方法
2020/09/27 Python
Django利用elasticsearch(搜索引擎)实现搜索功能
2020/11/26 Python
AmazeUI底部导航栏与分享按钮的示例代码
2020/08/18 HTML / CSS
Saks Fifth Avenue澳洲/亚太地区:萨克斯第五大道精品百货店
2019/06/09 全球购物
小小的船教学反思
2014/02/21 职场文书
社区交通安全实施方案
2014/03/22 职场文书
蛋糕店创业计划书范文
2014/09/21 职场文书
简易离婚协议书范本
2014/10/24 职场文书
大学升旗仪式主持词
2015/07/04 职场文书
Python 全局空间和局部空间
2022/04/06 Python
Python采集爬取京东商品信息和评论并存入MySQL
2022/04/12 Python
JS开发前端团队展示控制器来为成员引流
2022/08/14 Javascript