www.pudn.com > OpenCV-Intel.zip > cvcontourtree.cpp
/*M///////////////////////////////////////////////////////////////////////////////////////
//
// IMPORTANT: READ BEFORE DOWNLOADING, COPYING, INSTALLING OR USING.
//
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// If you do not agree to this license, do not download, install,
// copy or use the software.
//
//
// Intel License Agreement
// For Open Source Computer Vision Library
//
// Copyright (C) 2000, Intel Corporation, all rights reserved.
// Third party copyrights are property of their respective owners.
//
// Redistribution and use in source and binary forms, with or without modification,
// are permitted provided that the following conditions are met:
//
// * Redistribution's of source code must retain the above copyright notice,
// this list of conditions and the following disclaimer.
//
// * Redistribution's in binary form must reproduce the above copyright notice,
// this list of conditions and the following disclaimer in the documentation
// and/or other materials provided with the distribution.
//
// * The name of Intel Corporation may not be used to endorse or promote products
// derived from this software without specific prior written permission.
//
// This software is provided by the copyright holders and contributors "as is" and
// any express or implied warranties, including, but not limited to, the implied
// warranties of merchantability and fitness for a particular purpose are disclaimed.
// In no event shall the Intel Corporation or contributors be liable for any direct,
// indirect, incidental, special, exemplary, or consequential damages
// (including, but not limited to, procurement of substitute goods or services;
// loss of use, data, or profits; or business interruption) however caused
// and on any theory of liability, whether in contract, strict liability,
// or tort (including negligence or otherwise) arising in any way out of
// the use of this software, even if advised of the possibility of such damage.
//
//M*/
#include "_cv.h"
#define CV_MATCH_CHECK( status, cvFun ) \
{ \
status = cvFun; \
if( status != CV_OK ) \
goto M_END; \
}
static CvStatus
icvCalcTriAttr( const CvSeq * contour, CvPoint t2, CvPoint t1, int n1,
CvPoint t3, int n3, double *s, double *s_c,
double *h, double *a, double *b );
/*F///////////////////////////////////////////////////////////////////////////////////////
// Name: icvCreateContourTree
// Purpose:
// Create binary tree representation for the contour
// Context:
// Parameters:
// contour - pointer to input contour object.
// storage - pointer to the current storage block
// tree - output pointer to the binary tree representation
// threshold - threshold for the binary tree building
//
//F*/
static CvStatus
icvCreateContourTree( const CvSeq * contour, CvMemStorage * storage,
CvContourTree ** tree, double threshold )
{
CvPoint *pt_p; /* pointer to previos points */
CvPoint *pt_n; /* pointer to next points */
CvPoint *pt1, *pt2; /* pointer to current points */
CvPoint t, tp1, tp2, tp3, tn1, tn2, tn3;
int lpt, flag, i, j, i_tree, j_1, j_3, i_buf;
double s, sp1, sp2, sn1, sn2, s_c, sp1_c, sp2_c, sn1_c, sn2_c, h, hp1, hp2, hn1, hn2,
a, ap1, ap2, an1, an2, b, bp1, bp2, bn1, bn2;
double a_s_c, a_sp1_c;
_CvTrianAttr **ptr_p, **ptr_n, **ptr1, **ptr2; /* pointers to pointers of triangles */
_CvTrianAttr *cur_adr;
int *num_p, *num_n, *num1, *num2; /* numbers of input contour points */
int nm, nmp1, nmp2, nmp3, nmn1, nmn2, nmn3;
int seq_flags = 1, i_end, prev_null, prev2_null;
double koef = 1.5;
double eps = 1.e-7;
double e;
CvStatus status;
int hearder_size;
_CvTrianAttr tree_one, tree_two, *tree_end, *tree_root;
CvSeqWriter writer;
assert( contour != NULL && contour->total >= 4 );
status = CV_OK;
if( contour == NULL )
return CV_NULLPTR_ERR;
if( contour->total < 4 )
return CV_BADSIZE_ERR;
if( !CV_IS_SEQ_POLYGON( contour ))
return CV_BADFLAG_ERR;
/* Convert Sequence to array */
lpt = contour->total;
pt_p = pt_n = NULL;
num_p = num_n = NULL;
ptr_p = ptr_n = ptr1 = ptr2 = NULL;
tree_end = NULL;
pt_p = (CvPoint *) cvAlloc( lpt * sizeof( CvPoint ));
pt_n = (CvPoint *) cvAlloc( lpt * sizeof( CvPoint ));
num_p = (int *) cvAlloc( lpt * sizeof( int ));
num_n = (int *) cvAlloc( lpt * sizeof( int ));
hearder_size = sizeof( CvContourTree );
seq_flags = CV_SEQ_POLYGON_TREE;
cvStartWriteSeq( seq_flags, hearder_size, sizeof( _CvTrianAttr ), storage, &writer );
ptr_p = (_CvTrianAttr **) cvAlloc( lpt * sizeof( _CvTrianAttr * ));
ptr_n = (_CvTrianAttr **) cvAlloc( lpt * sizeof( _CvTrianAttr * ));
memset( ptr_p, 0, lpt * sizeof( _CvTrianAttr * ));
memset( ptr_n, 0, lpt * sizeof( _CvTrianAttr * ));
if( pt_p == NULL || pt_n == NULL )
return CV_OUTOFMEM_ERR;
if( ptr_p == NULL || ptr_n == NULL )
return CV_OUTOFMEM_ERR;
/* write fild for the binary tree root */
/* start_writer = writer; */
tree_one.pt.x = tree_one.pt.y = 0;
tree_one.sign = 0;
tree_one.area = 0;
tree_one.r1 = tree_one.r2 = 0;
tree_one.next_v1 = tree_one.next_v2 = tree_one.prev_v = NULL;
CV_WRITE_SEQ_ELEM( tree_one, writer );
tree_root = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( cvCvtSeqToArray( contour, (char *) pt_p ) == (char *) contour )
return CV_BADPOINT_ERR;
for( i = 0; i < lpt; i++ )
num_p[i] = i;
i = lpt;
flag = 0;
i_tree = 0;
e = 20.; /* initial threshold value */
ptr1 = ptr_p;
ptr2 = ptr_n;
pt1 = pt_p;
pt2 = pt_n;
num1 = num_p;
num2 = num_n;
/* binary tree constraction */
while( i > 4 )
{
if( flag == 0 )
{
ptr1 = ptr_p;
ptr2 = ptr_n;
pt1 = pt_p;
pt2 = pt_n;
num1 = num_p;
num2 = num_n;
flag = 1;
}
else
{
ptr1 = ptr_n;
ptr2 = ptr_p;
pt1 = pt_n;
pt2 = pt_p;
num1 = num_n;
num2 = num_p;
flag = 0;
}
t = pt1[0];
nm = num1[0];
tp1 = pt1[i - 1];
nmp1 = num1[i - 1];
tp2 = pt1[i - 2];
nmp2 = num1[i - 2];
tp3 = pt1[i - 3];
nmp3 = num1[i - 3];
tn1 = pt1[1];
nmn1 = num1[1];
tn2 = pt1[2];
nmn2 = num1[2];
i_buf = 0;
i_end = -1;
CV_MATCH_CHECK( status,
icvCalcTriAttr( contour, t, tp1, nmp1, tn1, nmn1, &s, &s_c, &h, &a,
&b ));
CV_MATCH_CHECK( status,
icvCalcTriAttr( contour, tp1, tp2, nmp2, t, nm, &sp1, &sp1_c, &hp1,
&ap1, &bp1 ));
CV_MATCH_CHECK( status,
icvCalcTriAttr( contour, tp2, tp3, nmp3, tp1, nmp1, &sp2, &sp2_c, &hp2,
&ap2, &bp2 ));
CV_MATCH_CHECK( status,
icvCalcTriAttr( contour, tn1, t, nm, tn2, nmn2, &sn1, &sn1_c, &hn1,
&an1, &bn1 ));
j_3 = 3;
prev_null = prev2_null = 0;
for( j = 0; j < i; j++ )
{
tn3 = pt1[j_3];
nmn3 = num1[j_3];
if( j == 0 )
j_1 = i - 1;
else
j_1 = j - 1;
CV_MATCH_CHECK( status, icvCalcTriAttr( contour, tn2, tn1, nmn1, tn3, nmn3,
&sn2, &sn2_c, &hn2, &an2, &bn2 ));
if( (s_c < sp1_c && s_c < sp2_c && s_c <= sn1_c && s_c <= sn2_c && s_c < e) ||
(s_c == sp1_c && s_c <= sp2_c || s_c == sp2_c && s_c <= sp1_c) && s_c <= sn1_c
&& s_c <= sn2_c && s_c < e && j > 1 && prev2_null == 0 || (s_c < eps && j > 0
&& prev_null == 0) )
{
prev_null = prev2_null = 1;
if( s_c < threshold )
{
if( ptr1[j_1] == NULL && ptr1[j] == NULL )
{
if( i_buf > 0 )
ptr2[i_buf - 1] = NULL;
else
i_end = 0;
}
else
{
/* form next vertex */
tree_one.pt = t;
tree_one.sign = (char) (CV_SIGN( s ));
tree_one.r1 = h / a;
tree_one.r2 = b / a;
tree_one.area = fabs( s );
tree_one.next_v1 = ptr1[j_1];
tree_one.next_v2 = ptr1[j];
CV_WRITE_SEQ_ELEM( tree_one, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( ptr1[j_1] != NULL )
ptr1[j_1]->prev_v = cur_adr;
if( ptr1[j] != NULL )
ptr1[j]->prev_v = cur_adr;
if( i_buf > 0 )
ptr2[i_buf - 1] = cur_adr;
else
{
tree_end = (_CvTrianAttr *) writer.ptr;
i_end = 1;
}
i_tree++;
}
}
else
/* form next vertex */
{
tree_one.pt = t;
tree_one.sign = (char) (CV_SIGN( s ));
tree_one.area = fabs( s );
tree_one.r1 = h / a;
tree_one.r2 = b / a;
tree_one.next_v1 = ptr1[j_1];
tree_one.next_v2 = ptr1[j];
CV_WRITE_SEQ_ELEM( tree_one, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( ptr1[j_1] != NULL )
ptr1[j_1]->prev_v = cur_adr;
if( ptr1[j] != NULL )
ptr1[j]->prev_v = cur_adr;
if( i_buf > 0 )
ptr2[i_buf - 1] = cur_adr;
else
{
tree_end = cur_adr;
i_end = 1;
}
i_tree++;
}
}
else
/* the current triangle is'not LMIAT */
{
prev_null = 0;
switch (prev2_null)
{
case 0:
break;
case 1:
{
prev2_null = 2;
break;
}
case 2:
{
prev2_null = 0;
break;
}
}
if( j != i - 1 || i_end == -1 )
ptr2[i_buf] = ptr1[j];
else if( i_end == 0 )
ptr2[i_buf] = NULL;
else
ptr2[i_buf] = tree_end;
pt2[i_buf] = t;
num2[i_buf] = num1[j];
i_buf++;
}
/* go to next vertex */
tp3 = tp2;
tp2 = tp1;
tp1 = t;
t = tn1;
tn1 = tn2;
tn2 = tn3;
nmp3 = nmp2;
nmp2 = nmp1;
nmp1 = nm;
nm = nmn1;
nmn1 = nmn2;
nmn2 = nmn3;
sp2 = sp1;
sp1 = s;
s = sn1;
sn1 = sn2;
sp2_c = sp1_c;
sp1_c = s_c;
s_c = sn1_c;
sn1_c = sn2_c;
ap2 = ap1;
ap1 = a;
a = an1;
an1 = an2;
bp2 = bp1;
bp1 = b;
b = bn1;
bn1 = bn2;
hp2 = hp1;
hp1 = h;
h = hn1;
hn1 = hn2;
j_3++;
if( j_3 >= i )
j_3 = 0;
}
i = i_buf;
e = e * koef;
}
/* constract tree root */
if( i != 4 )
return CV_BADFACTOR_ERR;
t = pt2[0];
tn1 = pt2[1];
tn2 = pt2[2];
tp1 = pt2[3];
nm = num2[0];
nmn1 = num2[1];
nmn2 = num2[2];
nmp1 = num2[3];
/* first pair of the triangles */
CV_MATCH_CHECK( status,
icvCalcTriAttr( contour, t, tp1, nmp1, tn1, nmn1, &s, &s_c, &h, &a, &b ));
CV_MATCH_CHECK( status,
icvCalcTriAttr( contour, tn2, tn1, nmn1, tp1, nmp1, &sn2, &sn2_c, &hn2,
&an2, &bn2 ));
/* second pair of the triangles */
CV_MATCH_CHECK( status,
icvCalcTriAttr( contour, tn1, t, nm, tn2, nmn2, &sn1, &sn1_c, &hn1, &an1,
&bn1 ));
CV_MATCH_CHECK( status,
icvCalcTriAttr( contour, tp1, tn2, nmn2, t, nm, &sp1, &sp1_c, &hp1, &ap1,
&bp1 ));
a_s_c = fabs( s_c - sn2_c );
a_sp1_c = fabs( sp1_c - sn1_c );
if( a_s_c > a_sp1_c )
/* form child vertexs for the root */
{
tree_one.pt = t;
tree_one.sign = (char) (CV_SIGN( s ));
tree_one.area = fabs( s );
tree_one.r1 = h / a;
tree_one.r2 = b / a;
tree_one.next_v1 = ptr2[3];
tree_one.next_v2 = ptr2[0];
tree_two.pt = tn2;
tree_two.sign = (char) (CV_SIGN( sn2 ));
tree_two.area = fabs( sn2 );
tree_two.r1 = hn2 / an2;
tree_two.r2 = bn2 / an2;
tree_two.next_v1 = ptr2[1];
tree_two.next_v2 = ptr2[2];
CV_WRITE_SEQ_ELEM( tree_one, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( s_c > sn2_c )
{
if( ptr2[3] != NULL )
ptr2[3]->prev_v = cur_adr;
if( ptr2[0] != NULL )
ptr2[0]->prev_v = cur_adr;
ptr1[0] = cur_adr;
i_tree++;
CV_WRITE_SEQ_ELEM( tree_two, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( ptr2[1] != NULL )
ptr2[1]->prev_v = cur_adr;
if( ptr2[2] != NULL )
ptr2[2]->prev_v = cur_adr;
ptr1[1] = cur_adr;
i_tree++;
pt1[0] = tp1;
pt1[1] = tn1;
}
else
{
CV_WRITE_SEQ_ELEM( tree_two, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( ptr2[1] != NULL )
ptr2[1]->prev_v = cur_adr;
if( ptr2[2] != NULL )
ptr2[2]->prev_v = cur_adr;
ptr1[0] = cur_adr;
i_tree++;
CV_WRITE_SEQ_ELEM( tree_one, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( ptr2[3] != NULL )
ptr2[3]->prev_v = cur_adr;
if( ptr2[0] != NULL )
ptr2[0]->prev_v = cur_adr;
ptr1[1] = cur_adr;
i_tree++;
pt1[0] = tn1;
pt1[1] = tp1;
}
}
else
{
tree_one.pt = tp1;
tree_one.sign = (char) (CV_SIGN( sp1 ));
tree_one.area = fabs( sp1 );
tree_one.r1 = hp1 / ap1;
tree_one.r2 = bp1 / ap1;
tree_one.next_v1 = ptr2[2];
tree_one.next_v2 = ptr2[3];
tree_two.pt = tn1;
tree_two.sign = (char) (CV_SIGN( sn1 ));
tree_two.area = fabs( sn1 );
tree_two.r1 = hn1 / an1;
tree_two.r2 = bn1 / an1;
tree_two.next_v1 = ptr2[0];
tree_two.next_v2 = ptr2[1];
CV_WRITE_SEQ_ELEM( tree_one, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( sp1_c > sn1_c )
{
if( ptr2[2] != NULL )
ptr2[2]->prev_v = cur_adr;
if( ptr2[3] != NULL )
ptr2[3]->prev_v = cur_adr;
ptr1[0] = cur_adr;
i_tree++;
CV_WRITE_SEQ_ELEM( tree_two, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( ptr2[0] != NULL )
ptr2[0]->prev_v = cur_adr;
if( ptr2[1] != NULL )
ptr2[1]->prev_v = cur_adr;
ptr1[1] = cur_adr;
i_tree++;
pt1[0] = tn2;
pt1[1] = t;
}
else
{
CV_WRITE_SEQ_ELEM( tree_two, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( ptr2[0] != NULL )
ptr2[0]->prev_v = cur_adr;
if( ptr2[1] != NULL )
ptr2[1]->prev_v = cur_adr;
ptr1[0] = cur_adr;
i_tree++;
CV_WRITE_SEQ_ELEM( tree_one, writer );
cur_adr = (_CvTrianAttr *) (writer.ptr - writer.seq->elem_size);
if( ptr2[2] != NULL )
ptr2[2]->prev_v = cur_adr;
if( ptr2[3] != NULL )
ptr2[3]->prev_v = cur_adr;
ptr1[1] = cur_adr;
i_tree++;
pt1[0] = t;
pt1[1] = tn2;
}
}
/* form root */
s = cvContourArea( contour );
tree_root->pt = pt1[1];
tree_root->sign = 0;
tree_root->area = fabs( s );
tree_root->r1 = 0;
tree_root->r2 = 0;
tree_root->next_v1 = ptr1[0];
tree_root->next_v2 = ptr1[1];
tree_root->prev_v = NULL;
ptr1[0]->prev_v = (_CvTrianAttr *) tree_root;
ptr1[1]->prev_v = (_CvTrianAttr *) tree_root;
/* write binary tree root */
/* CV_WRITE_SEQ_ELEM (tree_one, start_writer); */
i_tree++;
/* create Sequence hearder */
*((CvSeq **) tree) = cvEndWriteSeq( &writer );
/* write points for the main segment into sequence header */
(*tree)->p1 = pt1[0];
M_END:
cvFree( (void**)&ptr_n );
cvFree( (void**)&ptr_p );
cvFree( (void**)&num_n );
cvFree( (void**)&num_p );
cvFree( (void**)&pt_n );
cvFree( (void**)&pt_p );
return status;
}
/****************************************************************************************\
triangle attributes calculations
\****************************************************************************************/
static CvStatus
icvCalcTriAttr( const CvSeq * contour, CvPoint t2, CvPoint t1, int n1,
CvPoint t3, int n3, double *s, double *s_c,
double *h, double *a, double *b )
{
double x13, y13, x12, y12, l_base, nx, ny, qq;
double eps = 1.e-5;
x13 = t3.x - t1.x;
y13 = t3.y - t1.y;
x12 = t2.x - t1.x;
y12 = t2.y - t1.y;
qq = x13 * x13 + y13 * y13;
l_base = cvSqrt( (float) (qq) );
if( l_base > eps )
{
nx = y13 / l_base;
ny = -x13 / l_base;
*h = nx * x12 + ny * y12;
*s = (*h) * l_base / 2.;
*b = nx * y12 - ny * x12;
*a = l_base;
/* calculate interceptive area */
*s_c = cvContourArea( contour, cvSlice(n1, n3+1));
}
else
{
*h = 0;
*s = 0;
*s_c = 0;
*b = 0;
*a = 0;
}
return CV_OK;
}
/*F///////////////////////////////////////////////////////////////////////////////////////
// Name: cvCreateContourTree
// Purpose:
// Create binary tree representation for the contour
// Context:
// Parameters:
// contour - pointer to input contour object.
// storage - pointer to the current storage block
// tree - output pointer to the binary tree representation
// threshold - threshold for the binary tree building
//
//F*/
CV_IMPL CvContourTree*
cvCreateContourTree( const CvSeq* contour, CvMemStorage* storage, double threshold )
{
CvContourTree* tree = 0;
CV_FUNCNAME( "cvCreateContourTree" );
__BEGIN__;
IPPI_CALL( icvCreateContourTree( contour, storage, &tree, threshold ));
__CLEANUP__;
__END__;
return tree;
}
/*F///////////////////////////////////////////////////////////////////////////////////////
// Name: icvContourFromContourTree
// Purpose:
// reconstracts contour from binary tree representation
// Context:
// Parameters:
// tree - pointer to the input binary tree representation
// storage - pointer to the current storage block
// contour - pointer to output contour object.
// criteria - criteria for the definition threshold value
// for the contour reconstracting (level or precision)
//F*/
CV_IMPL CvSeq*
cvContourFromContourTree( const CvContourTree* tree,
CvMemStorage* storage,
CvTermCriteria criteria )
{
CvSeq* contour = 0;
_CvTrianAttr **ptr_buf = 0; /* pointer to the pointer's buffer */
int *level_buf = 0;
int i_buf;
int lpt;
double area_all;
double threshold;
int cur_level;
int level;
int seq_flags;
char log_iter, log_eps;
int out_hearder_size;
_CvTrianAttr *tree_one = 0, tree_root; /* current vertex */
CvSeqReader reader;
CvSeqWriter writer;
CV_FUNCNAME("cvContourFromContourTree");
__BEGIN__;
if( !tree )
CV_ERROR( CV_StsNullPtr, "" );
if( !CV_IS_SEQ_POLYGON_TREE( tree ))
CV_ERROR_FROM_STATUS( CV_BADFLAG_ERR );
criteria = cvCheckTermCriteria( criteria, 0., 100 );
lpt = tree->total;
ptr_buf = NULL;
level_buf = NULL;
i_buf = 0;
cur_level = 0;
log_iter = (char) (criteria.type == CV_TERMCRIT_ITER ||
(criteria.type == CV_TERMCRIT_ITER + CV_TERMCRIT_EPS));
log_eps = (char) (criteria.type == CV_TERMCRIT_EPS ||
(criteria.type == CV_TERMCRIT_ITER + CV_TERMCRIT_EPS));
cvStartReadSeq( (CvSeq *) tree, &reader, 0 );
out_hearder_size = sizeof( CvContour );
seq_flags = CV_SEQ_POLYGON;
cvStartWriteSeq( seq_flags, out_hearder_size, sizeof( CvPoint ), storage, &writer );
ptr_buf = (_CvTrianAttr **) cvAlloc( lpt * sizeof( _CvTrianAttr * ));
if( ptr_buf == NULL )
CV_ERROR_FROM_STATUS( CV_OUTOFMEM_ERR );
if( log_iter )
{
level_buf = (int *) cvAlloc( lpt * (sizeof( int )));
if( level_buf == NULL )
CV_ERROR_FROM_STATUS( CV_OUTOFMEM_ERR );
}
memset( ptr_buf, 0, lpt * sizeof( _CvTrianAttr * ));
/* write the first tree root's point as a start point of the result contour */
CV_WRITE_SEQ_ELEM( tree->p1, writer );
/* write the second tree root"s point into buffer */
/* read the root of the tree */
CV_READ_SEQ_ELEM( tree_root, reader );
tree_one = &tree_root;
area_all = tree_one->area;
if( log_eps )
threshold = criteria.epsilon * area_all;
else
threshold = 10 * area_all;
if( log_iter )
level = criteria.max_iter;
else
level = -1;
/* contour from binary tree constraction */
while( i_buf >= 0 )
{
if( tree_one != NULL && (cur_level <= level || tree_one->area >= threshold) )
/* go to left sub tree for the vertex and save pointer to the right vertex */
/* into the buffer */
{
ptr_buf[i_buf] = tree_one;
if( log_iter )
{
level_buf[i_buf] = cur_level;
cur_level++;
}
i_buf++;
tree_one = tree_one->next_v1;
}
else
{
i_buf--;
if( i_buf >= 0 )
{
CvPoint pt = ptr_buf[i_buf]->pt;
CV_WRITE_SEQ_ELEM( pt, writer );
tree_one = ptr_buf[i_buf]->next_v2;
if( log_iter )
{
cur_level = level_buf[i_buf] + 1;
}
}
}
}
contour = cvEndWriteSeq( &writer );
cvBoundingRect( contour, 1 );
__CLEANUP__;
__END__;
cvFree( (void**)&level_buf );
cvFree( (void**)&ptr_buf );
return contour;
}