I copy the code in the OpenCV dir sampe/c/squares.c,
than change the GUI to wxWidgtes,
But the cvPyrUp and cvFindContours is crashed.
And
Code: Select all
cvCanny( tgray, gray, 0, thresh, 3 );
Please forgive my pool English.
Code: Select all
// returns sequence of squares detected on the image.
// the sequence is stored in the specified memory storage
CvSeq* TestDlg::findSquares4( IplImage* img, CvMemStorage* storage )
{
CvSeq* contours = NULL;
int i, c, l, N = 11;
CvSize sz = cvSize( img->width & -2, img->height & -2 );//末尾清零,变位2的整数倍
IplImage* timg = cvCloneImage( img ); // make a copy of input image
IplImage* gray = cvCreateImage( sz, 8, 1 );
IplImage* pyr = cvCreateImage( cvSize(sz.width/2, sz.height/2), 8, 3 );
IplImage* tgray = cvCreateImage( sz, 8, 1 );
//wxMessageBox("cvCreateImage");
CvSeq* result;
double s, t;
// create empty sequence that will contain points -
// 4 points per square (the square's vertices)
storage = cvCreateMemStorage(0);
CvSeq* squares = cvCreateSeq( 0, sizeof(CvSeq), sizeof(CvPoint), storage );
// select the maximum ROI in the image
// with the width and height divisible by 2
cvSetImageROI( timg, cvRect( 0, 0, sz.width, sz.height ));
// down-scale and upscale the image to filter out the noise
//cvPyrDown( timg, pyr, 7 );
//cvPyrUp( pyr, timg, 7 );
// find squares in every color plane of the image
for( c = 0; c < 3; c++ )
{
// extract the c-th color plane
cvSetImageCOI( timg, c+1 );
cvCopy( timg, tgray, 0 );
DrawTowxWindow(WxPanel_Rect, tgray);
// try several threshold levels
for( l = 0; l < N; l++ )
{
// hack: use Canny instead of zero threshold level.
// Canny helps to catch squares with gradient shading
if( l == 0 )
{
// apply Canny. Take the upper threshold from slider
// and set the lower to 0 (which forces edges merging)
cvCanny( tgray, gray, 0, thresh, 3 );
// dilate canny output to remove potential
// holes between edge segments
cvDilate( gray, gray, 0, 1 );
DrawTowxWindow(WxPanel_Rect, gray);
}
else
{
// apply threshold if l!=0:
// tgray(x,y) = gray(x,y) < (l+1)*255/N ? 255 : 0
cvThreshold( tgray, gray, (l+1)*255/N, 255, CV_THRESH_BINARY );
}
//Debug here
wxMessageBox(wxT("Pre cvFindContours"));
///////////////////////////////crash here//////////////////////////////////
cvFindContours( gray, storage, &contours, sizeof(CvContour),
CV_RETR_CCOMP, CV_CHAIN_APPROX_SIMPLE, cvPoint(0,0) );
wxMessageBox(wxT("cvFindContours"));
// test each contour
while( contours )
{
// approximate contour with accuracy proportional
// to the contour perimeter
result = cvApproxPoly( contours, sizeof(CvContour), storage,
CV_POLY_APPROX_DP, cvContourPerimeter(contours)*0.02, 0 );
wxMessageBox(wxT("cvApproxPoly"));
// square contours should have 4 vertices after approximation
// relatively large area (to filter out noisy contours)
// and be convex.
// Note: absolute value of an area is used because
// area may be positive or negative - in accordance with the
// contour orientation
if( result->total == 4 &&
cvContourArea(result,CV_WHOLE_SEQ,0) > 1000 &&
cvCheckContourConvexity(result) )
{
s = 0;
for( i = 0; i < 5; i++ )
{
// find minimum angle between joint
// edges (maximum of cosine)
if( i >= 2 )
{
t = fabs(angle(
(CvPoint*)cvGetSeqElem( result, i ),
(CvPoint*)cvGetSeqElem( result, i-2 ),
(CvPoint*)cvGetSeqElem( result, i-1 )));
s = s > t ? s : t;
}
}
// if cosines of all angles are small
// (all angles are ~90 degree) then write quandrange
// vertices to resultant sequence
if( s < 0.3 )//88.3或91.7度的余弦值为0.3,如果s<0.3,那么夹角在88.3-91.7度之间。
for( i = 0; i < 4; i++ )
cvSeqPush( squares,
(CvPoint*)cvGetSeqElem( result, i ));
}
// take the next contour
contours = contours->h_next;
}
}
}
wxMessageBox(wxT("End Loop"));
// release all the temporary images
cvReleaseImage( &gray );
cvReleaseImage( &pyr );
cvReleaseImage( &tgray );
cvReleaseImage( &timg );
return squares;//返回储存矩形顶点的数据序列
}