文章目录：
- 1、opencv 中cvtColor报错处理
- 2、android中如何用opencv处理倾斜校正的问题，求源代码
- 3、opencv中cvCvtColor函数在哪个库
- 4、请问OpenCV中的灰度变换函数cvCvtColor是运用哪种灰度变换？
opencv 中cvtColor报错处理
先调用cvCvtColor将图像转到HSV颜色空间，如：cvCvtColor(rgb,hsv,CV_BGR2HSV); 然后调用cvSplit函数，就可以将H分量分离出来，再来单独访问H分量，H对于的通道是0。
android中如何用opencv处理倾斜校正的问题，求源代码
#include "cv.h"
#include "highgui.h"
#include "cxcore.h"
#include "cvcam.h"
//图像的像素直接提取
#define _I(img,x,y) ((unsigned char*)((img)-imageData + (img)-widthStep*(y)))[(x)]
//亚像素级灰度值
#define _IF(image,x,y) ( ((int)(x+1)-(x))*((int)(y+1)-(y))*_I((image),(int)(x),(int)(y)) + ((int)(x+1)-(x))*((y)-(int)(y))*_I((image),(int)(x),(int)(y+1)) + ((x)-(int)(x))*((int)(y+1)-(y))*_I((image),(int)(x+1),(int)(y)) + ((x)-(int)(x))*((y)-(int)(y))*_I((image),(int)(x+1),(int)(y+1)) )//插值后的像素值(IN表示interpolation),x、y可以为小数
void callback(IplImage* image);
void main()
{
int ncams = cvcamGetCamerasCount( );//返回可以访问的摄像头数目
HWND mywin;
cvcamSetProperty(0, CVCAM_PROP_ENABLE, CVCAMTRUE);
cvcamSetProperty(0, CVCAM_PROP_RENDER, CVCAMTRUE);
mywin = (HWND)cvGetWindowHandle("cvcam window");
cvcamSetProperty(0, CVCAM_PROP_WINDOW, mywin);
cvcamSetProperty(0, CVCAM_PROP_CALLBACK, callback);
//cvcamGetProperty(0, CVCAM_VIDEOFORMAT,NULL);
cvNamedWindow( "径向矫正1", 1 );//创建窗口
cvNamedWindow( "径向矫正2", 1 );//创建窗口
cvcamInit( );
cvcamStart( );
cvWaitKey(0);
cvcamStop( );
cvcamExit( );
cvDestroyWindow( "径向矫正1" );//销毁窗口
cvDestroyWindow( "径向矫正2" );//销毁窗口
}
void callback(IplImage* image)
{
IplImage* Show1 = cvCreateImage( cvSize(320,240), IPL_DEPTH_8U, 1);
IplImage* Show2 = cvCreateImage( cvSize(420,340), IPL_DEPTH_8U, 1);
IplImage* ImageC1 = cvCreateImage( cvSize(320,240), IPL_DEPTH_8U, 1);
//转换为灰度图
cvCvtColor( image, ImageC1, CV_RGB2GRAY);
cvFlip( ImageC1, NULL, 0);
double *mi;
double *md;
mi = new double[3*3];
md = new double[4];
CvMat intrinsic_matrix,distortion_coeffs;
//摄像机内参数
cvInitMatHeader(intrinsic_matrix,3,3,CV_64FC1,mi);
//镜头畸变参数
cvInitMatHeader(distortion_coeffs,1,4,CV_64FC1,md);
/////////////////////////////////////////////////
////////////////////////////320*240 120度广角镜头
//参数由matlab获得
double fc1,fc2,cc1,cc2,kc1,kc2,kc3,kc4;
fc1 = 667.23923/2.5;
fc2 = 669.78156/2.5;
cc1 = 429.96933/2.5;
cc2 = 351.48350/2.5;
kc1 = -0.40100;
kc2 = 0.19463;
kc3 = 0.00508;
kc4 = -0.00051;
cvmSet(intrinsic_matrix, 0, 0, fc1);
cvmSet(intrinsic_matrix, 0, 1, 0);
cvmSet(intrinsic_matrix, 0, 2, cc1);
cvmSet(intrinsic_matrix, 1, 0, 0);
cvmSet(intrinsic_matrix, 1, 1, fc2);
cvmSet(intrinsic_matrix, 1, 2, cc2);
cvmSet(intrinsic_matrix, 2, 0, 0);
cvmSet(intrinsic_matrix, 2, 1, 0);
cvmSet(intrinsic_matrix, 2, 2, 1);
cvmSet(distortion_coeffs, 0, 0, kc1);
cvmSet(distortion_coeffs, 0, 1, kc2);
cvmSet(distortion_coeffs, 0, 2, kc3);
cvmSet(distortion_coeffs, 0, 3, kc4);
////////////////////////////320*240 120度广角镜头
/////////////////////////////////////////////////
//矫正畸变(opencv)
cvUndistort2( ImageC1, Show1, intrinsic_matrix, distortion_coeffs);
//矫正畸变
for (int nx=0; nx420; nx++)
{
for (int ny=0; ny340; ny++)
{
double x=nx-50;
double y=ny-50;
double xx=(x-cc1)/fc1;
double yy=(y-cc2)/fc2;
double r2=pow(xx,2)+pow(yy,2);
double r4=pow(r2,2);
double xxx=xx*(1+kc1*r2+kc2*r4)+2*kc3*xx*yy+kc4*(r2+2*xx*xx);
double yyy=yy*(1+kc1*r2+kc2*r4)+2*kc4*xx*yy+kc3*(r2+2*yy*yy);
double xxxx = xxx*fc1+cc1;
double yyyy = yyy*fc2+cc2;
if (xxxx0 xxxx320 yyyy0 yyyy240)
{
_I(Show2,nx,ny) = (int)_IF(ImageC1,xxxx,yyyy);
}
else
{
_I(Show2,nx,ny) = 0;
}
}
}
//画线
cvLine( Show1, cvPoint(0,10), cvPoint(320,10), cvScalar(255,255,255),3 );
cvLine( Show1, cvPoint(0,230), cvPoint(320,230), cvScalar(255,255,255),3 );
cvLine( Show1, cvPoint(10,0), cvPoint(10,240), cvScalar(255,255,255),3 );
cvLine( Show1, cvPoint(310,0), cvPoint(310,240), cvScalar(255,255,255),3 );
cvLine( Show1, cvPoint(0,0), cvPoint(320,240), cvScalar(255,255,255),3 );
cvLine( Show1, cvPoint(0,240), cvPoint(320,0), cvScalar(255,255,255),3 );
cvLine( Show1, cvPoint(0,10), cvPoint(320,10), cvScalar(0,0,0) );
cvLine( Show1, cvPoint(0,230), cvPoint(320,230), cvScalar(0,0,0) );
cvLine( Show1, cvPoint(10,0), cvPoint(10,240), cvScalar(0,0,0) );
cvLine( Show1, cvPoint(310,0), cvPoint(310,240), cvScalar(0,0,0) );
cvLine( Show1, cvPoint(0,0), cvPoint(320,240), cvScalar(0,0,0) );
cvLine( Show1, cvPoint(0,240), cvPoint(320,0), cvScalar(0,0,0) );
//显示
cvShowImage("径向矫正1", Show1);
cvShowImage("径向矫正2", Show2);
cvWaitKey(1);
cvReleaseImage( Show1 );
cvReleaseImage( Show2 );
cvReleaseImage( ImageC1 );
}
来自:
opencv中cvCvtColor函数在哪个库
下载opencv source，RGB2Gray部分源码在opencv-4.0.1\modules\imgproc\src\color_rgb.cpp文件中，如下：
templatetypename _Tp struct RGB2Gray
{
typedef _Tp channel_type;
RGB2Gray(int _srccn, int blueIdx, const float* _coeffs) : srccn(_srccn)
{
static const float coeffs0[] = { R2YF, G2YF, B2YF };
memcpy( coeffs, _coeffs ? _coeffs : coeffs0, 3*sizeof(coeffs[0]) );
if(blueIdx == 0)
std::swap(coeffs[0], coeffs[2]); }
void operator()(const _Tp* src, _Tp* dst, int n) const
{
int scn = srccn;
float cb = coeffs[0], cg = coeffs[1], cr = coeffs[2];
for(int i = 0; i n; i++, src += scn)
dst[i] = saturate_cast_Tp(src[0]*cb + src[1]*cg + src[2]*cr); }
int srccn;
float coeffs[3];
};
其中YF, G2YF, B2YF定义在文件color.hpp中，代码如下：
//constants for conversion from/to RGB and Gray, YUV, YCrCb according to BT.601
const float B2YF = 0.114f;
const float G2YF = 0.587f;
const float R2YF = 0.299f;
请问OpenCV中的灰度变换函数cvCvtColor是运用哪种灰度变换？
cvCvtColor(...),是Opencv里的颜色空间转换函数，可以实现RGB颜色向HSV,HSI等颜色空间的转换，也可以转换为灰度图像。
参数CV_RGB2GRAY是RGB到gray。
具体用的线性灰度变换函数是：
Gray=0.299*R+0.587*G+0.144*B
你可以通过查看OpenCV的documentation或者源代码，来了解具体的实现。
Show1, cvPoint(10,0), cvPoint(10,240), cvScalar(0,0,0) ); cvLine( Show1, cvPoint(310,0), cvPoint(310,240), c