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#include "precomp.hpp"
void cv::cornerSubPix( InputArray _image, InputOutputArray _corners,
Size win, Size zeroZone, TermCriteria criteria )
{
const int MAX_ITERS = 100;
int win_w = win.width * 2 + 1, win_h = win.height * 2 + 1;
int i, j, k;
int max_iters = (criteria.type & CV_TERMCRIT_ITER) ? MIN(MAX(criteria.maxCount, 1), MAX_ITERS) : MAX_ITERS;
double eps = (criteria.type & CV_TERMCRIT_EPS) ? MAX(criteria.epsilon, 0.) : 0;
eps *= eps; // use square of error in comparsion operations
cv::Mat src = _image.getMat(), cornersmat = _corners.getMat();
int count = cornersmat.checkVector(2, CV_32F);
CV_Assert( count >= 0 );
Point2f* corners = cornersmat.ptr<Point2f>();
if( count == 0 )
return;
CV_Assert( win.width > 0 && win.height > 0 );
CV_Assert( src.cols >= win.width*2 + 5 && src.rows >= win.height*2 + 5 );
CV_Assert( src.channels() == 1 );
Mat maskm(win_h, win_w, CV_32F), subpix_buf(win_h+2, win_w+2, CV_32F);
float* mask = maskm.ptr<float>();
for( i = 0; i < win_h; i++ )
{
float y = (float)(i - win.height)/win.height;
float vy = std::exp(-y*y);
for( j = 0; j < win_w; j++ )
{
float x = (float)(j - win.width)/win.width;
mask[i * win_w + j] = (float)(vy*std::exp(-x*x));
}
}
// make zero_zone
if( zeroZone.width >= 0 && zeroZone.height >= 0 &&
zeroZone.width * 2 + 1 < win_w && zeroZone.height * 2 + 1 < win_h )
{
for( i = win.height - zeroZone.height; i <= win.height + zeroZone.height; i++ )
{
for( j = win.width - zeroZone.width; j <= win.width + zeroZone.width; j++ )
{
mask[i * win_w + j] = 0;
}
}
}
// do optimization loop for all the points
for( int pt_i = 0; pt_i < count; pt_i++ )
{
Point2f cT = corners[pt_i], cI = cT;
int iter = 0;
double err = 0;
do
{
Point2f cI2;
double a = 0, b = 0, c = 0, bb1 = 0, bb2 = 0;
getRectSubPix(src, Size(win_w+2, win_h+2), cI, subpix_buf, subpix_buf.type());
const float* subpix = &subpix_buf.at<float>(1,1);
// process gradient
for( i = 0, k = 0; i < win_h; i++, subpix += win_w + 2 )
{
double py = i - win.height;
for( j = 0; j < win_w; j++, k++ )
{
double m = mask[k];
double tgx = subpix[j+1] - subpix[j-1];
double tgy = subpix[j+win_w+2] - subpix[j-win_w-2];
double gxx = tgx * tgx * m;
double gxy = tgx * tgy * m;
double gyy = tgy * tgy * m;
double px = j - win.width;
a += gxx;
b += gxy;
c += gyy;
bb1 += gxx * px + gxy * py;
bb2 += gxy * px + gyy * py;
}
}
double det=a*c-b*b;
if( fabs( det ) <= DBL_EPSILON*DBL_EPSILON )
break;
// 2x2 matrix inversion
double scale=1.0/det;
cI2.x = (float)(cI.x + c*scale*bb1 - b*scale*bb2);
cI2.y = (float)(cI.y - b*scale*bb1 + a*scale*bb2);
err = (cI2.x - cI.x) * (cI2.x - cI.x) + (cI2.y - cI.y) * (cI2.y - cI.y);
cI = cI2;
if( cI.x < 0 || cI.x >= src.cols || cI.y < 0 || cI.y >= src.rows )
break;
}
while( ++iter < max_iters && err > eps );
// if new point is too far from initial, it means poor convergence.
// leave initial point as the result
if( fabs( cI.x - cT.x ) > win.width || fabs( cI.y - cT.y ) > win.height )
cI = cT;
corners[pt_i] = cI;
}
}
CV_IMPL void
cvFindCornerSubPix( const void* srcarr, CvPoint2D32f* _corners,
int count, CvSize win, CvSize zeroZone,
CvTermCriteria criteria )
{
if(!_corners || count <= 0)
return;
cv::Mat src = cv::cvarrToMat(srcarr), corners(count, 1, CV_32FC2, _corners);
cv::cornerSubPix(src, corners, win, zeroZone, criteria);
}
/* End of file. */