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opencv/modules/features2d/src/mser.cpp

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/* Redistribution and use in source and binary forms, with or
* without modification, are permitted provided that the following
* conditions are met:
* Redistributions of source code must retain the above
* copyright notice, this list of conditions and the following
* disclaimer.
* Redistributions 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 Contributor 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 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.
* Copyright© 2009, Liu Liu All rights reserved.
*
* OpenCV functions for MSER extraction
*
* 1. there are two different implementation of MSER, one for grey image, one for color image
* 2. the grey image algorithm is taken from: Linear Time Maximally Stable Extremal Regions;
* the paper claims to be faster than union-find method;
* it actually get 1.5~2m/s on my centrino L7200 1.2GHz laptop.
* 3. the color image algorithm is taken from: Maximally Stable Colour Regions for Recognition and Match;
* it should be much slower than grey image method ( 3~4 times );
* the chi_table.h file is taken directly from paper's source code which is distributed under GPL.
* 4. though the name is *contours*, the result actually is a list of point set.
*/
#include "precomp.hpp"
namespace cv
{
const int TABLE_SIZE = 400;
static double chitab3[]={0, 0.0150057, 0.0239478, 0.0315227,
0.0383427, 0.0446605, 0.0506115, 0.0562786,
0.0617174, 0.0669672, 0.0720573, 0.0770099,
0.081843, 0.0865705, 0.0912043, 0.0957541,
0.100228, 0.104633, 0.108976, 0.113261,
0.117493, 0.121676, 0.125814, 0.12991,
0.133967, 0.137987, 0.141974, 0.145929,
0.149853, 0.15375, 0.15762, 0.161466,
0.165287, 0.169087, 0.172866, 0.176625,
0.180365, 0.184088, 0.187794, 0.191483,
0.195158, 0.198819, 0.202466, 0.2061,
0.209722, 0.213332, 0.216932, 0.220521,
0.2241, 0.22767, 0.231231, 0.234783,
0.238328, 0.241865, 0.245395, 0.248918,
0.252435, 0.255947, 0.259452, 0.262952,
0.266448, 0.269939, 0.273425, 0.276908,
0.280386, 0.283862, 0.287334, 0.290803,
0.29427, 0.297734, 0.301197, 0.304657,
0.308115, 0.311573, 0.315028, 0.318483,
0.321937, 0.32539, 0.328843, 0.332296,
0.335749, 0.339201, 0.342654, 0.346108,
0.349562, 0.353017, 0.356473, 0.35993,
0.363389, 0.366849, 0.37031, 0.373774,
0.377239, 0.380706, 0.384176, 0.387648,
0.391123, 0.3946, 0.39808, 0.401563,
0.405049, 0.408539, 0.412032, 0.415528,
0.419028, 0.422531, 0.426039, 0.429551,
0.433066, 0.436586, 0.440111, 0.44364,
0.447173, 0.450712, 0.454255, 0.457803,
0.461356, 0.464915, 0.468479, 0.472049,
0.475624, 0.479205, 0.482792, 0.486384,
0.489983, 0.493588, 0.4972, 0.500818,
0.504442, 0.508073, 0.511711, 0.515356,
0.519008, 0.522667, 0.526334, 0.530008,
0.533689, 0.537378, 0.541075, 0.54478,
0.548492, 0.552213, 0.555942, 0.55968,
0.563425, 0.56718, 0.570943, 0.574715,
0.578497, 0.582287, 0.586086, 0.589895,
0.593713, 0.597541, 0.601379, 0.605227,
0.609084, 0.612952, 0.61683, 0.620718,
0.624617, 0.628526, 0.632447, 0.636378,
0.64032, 0.644274, 0.648239, 0.652215,
0.656203, 0.660203, 0.664215, 0.668238,
0.672274, 0.676323, 0.680384, 0.684457,
0.688543, 0.692643, 0.696755, 0.700881,
0.70502, 0.709172, 0.713339, 0.717519,
0.721714, 0.725922, 0.730145, 0.734383,
0.738636, 0.742903, 0.747185, 0.751483,
0.755796, 0.760125, 0.76447, 0.768831,
0.773208, 0.777601, 0.782011, 0.786438,
0.790882, 0.795343, 0.799821, 0.804318,
0.808831, 0.813363, 0.817913, 0.822482,
0.827069, 0.831676, 0.836301, 0.840946,
0.84561, 0.850295, 0.854999, 0.859724,
0.864469, 0.869235, 0.874022, 0.878831,
0.883661, 0.888513, 0.893387, 0.898284,
0.903204, 0.908146, 0.913112, 0.918101,
0.923114, 0.928152, 0.933214, 0.938301,
0.943413, 0.94855, 0.953713, 0.958903,
0.964119, 0.969361, 0.974631, 0.979929,
0.985254, 0.990608, 0.99599, 1.0014,
1.00684, 1.01231, 1.01781, 1.02335,
1.02891, 1.0345, 1.04013, 1.04579,
1.05148, 1.05721, 1.06296, 1.06876,
1.07459, 1.08045, 1.08635, 1.09228,
1.09826, 1.10427, 1.11032, 1.1164,
1.12253, 1.1287, 1.1349, 1.14115,
1.14744, 1.15377, 1.16015, 1.16656,
1.17303, 1.17954, 1.18609, 1.19269,
1.19934, 1.20603, 1.21278, 1.21958,
1.22642, 1.23332, 1.24027, 1.24727,
1.25433, 1.26144, 1.26861, 1.27584,
1.28312, 1.29047, 1.29787, 1.30534,
1.31287, 1.32046, 1.32812, 1.33585,
1.34364, 1.3515, 1.35943, 1.36744,
1.37551, 1.38367, 1.39189, 1.4002,
1.40859, 1.41705, 1.42561, 1.43424,
1.44296, 1.45177, 1.46068, 1.46967,
1.47876, 1.48795, 1.49723, 1.50662,
1.51611, 1.52571, 1.53541, 1.54523,
1.55517, 1.56522, 1.57539, 1.58568,
1.59611, 1.60666, 1.61735, 1.62817,
1.63914, 1.65025, 1.66152, 1.67293,
1.68451, 1.69625, 1.70815, 1.72023,
1.73249, 1.74494, 1.75757, 1.77041,
1.78344, 1.79669, 1.81016, 1.82385,
1.83777, 1.85194, 1.86635, 1.88103,
1.89598, 1.91121, 1.92674, 1.94257,
1.95871, 1.97519, 1.99201, 2.0092,
2.02676, 2.04471, 2.06309, 2.08189,
2.10115, 2.12089, 2.14114, 2.16192,
2.18326, 2.2052, 2.22777, 2.25101,
2.27496, 2.29966, 2.32518, 2.35156,
2.37886, 2.40717, 2.43655, 2.46709,
2.49889, 2.53206, 2.56673, 2.60305,
2.64117, 2.6813, 2.72367, 2.76854,
2.81623, 2.86714, 2.92173, 2.98059,
3.04446, 3.1143, 3.19135, 3.27731,
3.37455, 3.48653, 3.61862, 3.77982,
3.98692, 4.2776, 4.77167, 133.333 };
typedef struct LinkedPoint
{
struct LinkedPoint* prev;
struct LinkedPoint* next;
Point pt;
}
LinkedPoint;
// the history of region grown
typedef struct MSERGrowHistory
{
struct MSERGrowHistory* shortcut;
struct MSERGrowHistory* child;
int stable; // when it ever stabled before, record the size
int val;
int size;
}
MSERGrowHistory;
typedef struct MSERConnectedComp
{
LinkedPoint* head;
LinkedPoint* tail;
MSERGrowHistory* history;
unsigned long grey_level;
int size;
int dvar; // the derivative of last var
float var; // the current variation (most time is the variation of one-step back)
}
MSERConnectedComp;
// Linear Time MSER claims by using bsf can get performance gain, here is the implementation
// however it seems that will not do any good in real world test
inline void _bitset(unsigned long * a, unsigned long b)
{
*a |= 1<<b;
}
inline void _bitreset(unsigned long * a, unsigned long b)
{
*a &= ~(1<<b);
}
struct MSERParams
{
MSERParams( int _delta, int _minArea, int _maxArea, double _maxVariation,
double _minDiversity, int _maxEvolution, double _areaThreshold,
double _minMargin, int _edgeBlurSize )
: delta(_delta), minArea(_minArea), maxArea(_maxArea), maxVariation(_maxVariation),
minDiversity(_minDiversity), maxEvolution(_maxEvolution), areaThreshold(_areaThreshold),
minMargin(_minMargin), edgeBlurSize(_edgeBlurSize)
{}
int delta;
int minArea;
int maxArea;
double maxVariation;
double minDiversity;
int maxEvolution;
double areaThreshold;
double minMargin;
int edgeBlurSize;
};
// clear the connected component in stack
static void
initMSERComp( MSERConnectedComp* comp )
{
comp->size = 0;
comp->var = 0;
comp->dvar = 1;
comp->history = NULL;
}
// add history of size to a connected component
static void
MSERNewHistory( MSERConnectedComp* comp, MSERGrowHistory* history )
{
history->child = history;
if ( NULL == comp->history )
{
history->shortcut = history;
history->stable = 0;
} else {
comp->history->child = history;
history->shortcut = comp->history->shortcut;
history->stable = comp->history->stable;
}
history->val = comp->grey_level;
history->size = comp->size;
comp->history = history;
}
// merging two connected component
static void
MSERMergeComp( MSERConnectedComp* comp1,
MSERConnectedComp* comp2,
MSERConnectedComp* comp,
MSERGrowHistory* history )
{
LinkedPoint* head;
LinkedPoint* tail;
comp->grey_level = comp2->grey_level;
history->child = history;
// select the winner by size
if ( comp1->size >= comp2->size )
{
if ( NULL == comp1->history )
{
history->shortcut = history;
history->stable = 0;
} else {
comp1->history->child = history;
history->shortcut = comp1->history->shortcut;
history->stable = comp1->history->stable;
}
if ( NULL != comp2->history && comp2->history->stable > history->stable )
history->stable = comp2->history->stable;
history->val = comp1->grey_level;
history->size = comp1->size;
// put comp1 to history
comp->var = comp1->var;
comp->dvar = comp1->dvar;
if ( comp1->size > 0 && comp2->size > 0 )
{
comp1->tail->next = comp2->head;
comp2->head->prev = comp1->tail;
}
head = ( comp1->size > 0 ) ? comp1->head : comp2->head;
tail = ( comp2->size > 0 ) ? comp2->tail : comp1->tail;
// always made the newly added in the last of the pixel list (comp1 ... comp2)
} else {
if ( NULL == comp2->history )
{
history->shortcut = history;
history->stable = 0;
} else {
comp2->history->child = history;
history->shortcut = comp2->history->shortcut;
history->stable = comp2->history->stable;
}
if ( NULL != comp1->history && comp1->history->stable > history->stable )
history->stable = comp1->history->stable;
history->val = comp2->grey_level;
history->size = comp2->size;
// put comp2 to history
comp->var = comp2->var;
comp->dvar = comp2->dvar;
if ( comp1->size > 0 && comp2->size > 0 )
{
comp2->tail->next = comp1->head;
comp1->head->prev = comp2->tail;
}
head = ( comp2->size > 0 ) ? comp2->head : comp1->head;
tail = ( comp1->size > 0 ) ? comp1->tail : comp2->tail;
// always made the newly added in the last of the pixel list (comp2 ... comp1)
}
comp->head = head;
comp->tail = tail;
comp->history = history;
comp->size = comp1->size + comp2->size;
}
static float
MSERVariationCalc( MSERConnectedComp* comp, int delta )
{
MSERGrowHistory* history = comp->history;
int val = comp->grey_level;
if ( NULL != history )
{
MSERGrowHistory* shortcut = history->shortcut;
while ( shortcut != shortcut->shortcut && shortcut->val + delta > val )
shortcut = shortcut->shortcut;
MSERGrowHistory* child = shortcut->child;
while ( child != child->child && child->val + delta <= val )
{
shortcut = child;
child = child->child;
}
// get the position of history where the shortcut->val <= delta+val and shortcut->child->val >= delta+val
history->shortcut = shortcut;
return (float)(comp->size-shortcut->size)/(float)shortcut->size;
// here is a small modification of MSER where cal ||R_{i}-R_{i-delta}||/||R_{i-delta}||
// in standard MSER, cal ||R_{i+delta}-R_{i-delta}||/||R_{i}||
// my calculation is simpler and much easier to implement
}
return 1.;
}
static bool MSERStableCheck( MSERConnectedComp* comp, MSERParams params )
{
// tricky part: it actually check the stablity of one-step back
if ( comp->history == NULL || comp->history->size <= params.minArea || comp->history->size >= params.maxArea )
return 0;
float div = (float)(comp->history->size-comp->history->stable)/(float)comp->history->size;
float var = MSERVariationCalc( comp, params.delta );
int dvar = ( comp->var < var || (unsigned long)(comp->history->val + 1) < comp->grey_level );
int stable = ( dvar && !comp->dvar && comp->var < params.maxVariation && div > params.minDiversity );
comp->var = var;
comp->dvar = dvar;
if ( stable )
comp->history->stable = comp->history->size;
return stable != 0;
}
// add a pixel to the pixel list
static void accumulateMSERComp( MSERConnectedComp* comp, LinkedPoint* point )
{
if ( comp->size > 0 )
{
point->prev = comp->tail;
comp->tail->next = point;
point->next = NULL;
} else {
point->prev = NULL;
point->next = NULL;
comp->head = point;
}
comp->tail = point;
comp->size++;
}
// convert the point set to CvSeq
static CvContour* MSERToContour( MSERConnectedComp* comp, CvMemStorage* storage )
{
CvSeq* _contour = cvCreateSeq( CV_SEQ_KIND_GENERIC|CV_32SC2, sizeof(CvContour), sizeof(CvPoint), storage );
CvContour* contour = (CvContour*)_contour;
cvSeqPushMulti( _contour, 0, comp->history->size );
LinkedPoint* lpt = comp->head;
for ( int i = 0; i < comp->history->size; i++ )
{
CvPoint* pt = CV_GET_SEQ_ELEM( CvPoint, _contour, i );
pt->x = lpt->pt.x;
pt->y = lpt->pt.y;
lpt = lpt->next;
}
cvBoundingRect( contour );
return contour;
}
// to preprocess src image to following format
// 32-bit image
// > 0 is available, < 0 is visited
// 17~19 bits is the direction
// 8~11 bits is the bucket it falls to (for BitScanForward)
// 0~8 bits is the color
static int* preprocessMSER_8UC1( CvMat* img,
int*** heap_cur,
CvMat* src,
CvMat* mask )
{
int srccpt = src->step-src->cols;
int cpt_1 = img->cols-src->cols-1;
int* imgptr = img->data.i;
int* startptr;
int level_size[256];
for ( int i = 0; i < 256; i++ )
level_size[i] = 0;
for ( int i = 0; i < src->cols+2; i++ )
{
*imgptr = -1;
imgptr++;
}
imgptr += cpt_1-1;
uchar* srcptr = src->data.ptr;
if ( mask )
{
startptr = 0;
uchar* maskptr = mask->data.ptr;
for ( int i = 0; i < src->rows; i++ )
{
*imgptr = -1;
imgptr++;
for ( int j = 0; j < src->cols; j++ )
{
if ( *maskptr )
{
if ( !startptr )
startptr = imgptr;
*srcptr = 0xff-*srcptr;
level_size[*srcptr]++;
*imgptr = ((*srcptr>>5)<<8)|(*srcptr);
} else {
*imgptr = -1;
}
imgptr++;
srcptr++;
maskptr++;
}
*imgptr = -1;
imgptr += cpt_1;
srcptr += srccpt;
maskptr += srccpt;
}
} else {
startptr = imgptr+img->cols+1;
for ( int i = 0; i < src->rows; i++ )
{
*imgptr = -1;
imgptr++;
for ( int j = 0; j < src->cols; j++ )
{
*srcptr = 0xff-*srcptr;
level_size[*srcptr]++;
*imgptr = ((*srcptr>>5)<<8)|(*srcptr);
imgptr++;
srcptr++;
}
*imgptr = -1;
imgptr += cpt_1;
srcptr += srccpt;
}
}
for ( int i = 0; i < src->cols+2; i++ )
{
*imgptr = -1;
imgptr++;
}
heap_cur[0][0] = 0;
for ( int i = 1; i < 256; i++ )
{
heap_cur[i] = heap_cur[i-1]+level_size[i-1]+1;
heap_cur[i][0] = 0;
}
return startptr;
}
static void extractMSER_8UC1_Pass( int* ioptr,
int* imgptr,
int*** heap_cur,
LinkedPoint* ptsptr,
MSERGrowHistory* histptr,
MSERConnectedComp* comptr,
int step,
int stepmask,
int stepgap,
MSERParams params,
int color,
CvSeq* contours,
CvMemStorage* storage )
{
comptr->grey_level = 256;
comptr++;
comptr->grey_level = (*imgptr)&0xff;
initMSERComp( comptr );
*imgptr |= 0x80000000;
heap_cur += (*imgptr)&0xff;
int dir[] = { 1, step, -1, -step };
#ifdef __INTRIN_ENABLED__
unsigned long heapbit[] = { 0, 0, 0, 0, 0, 0, 0, 0 };
unsigned long* bit_cur = heapbit+(((*imgptr)&0x700)>>8);
#endif
for ( ; ; )
{
// take tour of all the 4 directions
while ( ((*imgptr)&0x70000) < 0x40000 )
{
// get the neighbor
int* imgptr_nbr = imgptr+dir[((*imgptr)&0x70000)>>16];
if ( *imgptr_nbr >= 0 ) // if the neighbor is not visited yet
{
*imgptr_nbr |= 0x80000000; // mark it as visited
if ( ((*imgptr_nbr)&0xff) < ((*imgptr)&0xff) )
{
// when the value of neighbor smaller than current
// push current to boundary heap and make the neighbor to be the current one
// create an empty comp
(*heap_cur)++;
**heap_cur = imgptr;
*imgptr += 0x10000;
heap_cur += ((*imgptr_nbr)&0xff)-((*imgptr)&0xff);
#ifdef __INTRIN_ENABLED__
_bitset( bit_cur, (*imgptr)&0x1f );
bit_cur += (((*imgptr_nbr)&0x700)-((*imgptr)&0x700))>>8;
#endif
imgptr = imgptr_nbr;
comptr++;
initMSERComp( comptr );
comptr->grey_level = (*imgptr)&0xff;
continue;
} else {
// otherwise, push the neighbor to boundary heap
heap_cur[((*imgptr_nbr)&0xff)-((*imgptr)&0xff)]++;
*heap_cur[((*imgptr_nbr)&0xff)-((*imgptr)&0xff)] = imgptr_nbr;
#ifdef __INTRIN_ENABLED__
_bitset( bit_cur+((((*imgptr_nbr)&0x700)-((*imgptr)&0x700))>>8), (*imgptr_nbr)&0x1f );
#endif
}
}
*imgptr += 0x10000;
}
int imsk = (int)(imgptr-ioptr);
ptsptr->pt = cvPoint( imsk&stepmask, imsk>>stepgap );
// get the current location
accumulateMSERComp( comptr, ptsptr );
ptsptr++;
// get the next pixel from boundary heap
if ( **heap_cur )
{
imgptr = **heap_cur;
(*heap_cur)--;
#ifdef __INTRIN_ENABLED__
if ( !**heap_cur )
_bitreset( bit_cur, (*imgptr)&0x1f );
#endif
} else {
#ifdef __INTRIN_ENABLED__
bool found_pixel = 0;
unsigned long pixel_val;
for ( int i = ((*imgptr)&0x700)>>8; i < 8; i++ )
{
if ( _BitScanForward( &pixel_val, *bit_cur ) )
{
found_pixel = 1;
pixel_val += i<<5;
heap_cur += pixel_val-((*imgptr)&0xff);
break;
}
bit_cur++;
}
if ( found_pixel )
#else
heap_cur++;
unsigned long pixel_val = 0;
for ( unsigned long i = ((*imgptr)&0xff)+1; i < 256; i++ )
{
if ( **heap_cur )
{
pixel_val = i;
break;
}
heap_cur++;
}
if ( pixel_val )
#endif
{
imgptr = **heap_cur;
(*heap_cur)--;
#ifdef __INTRIN_ENABLED__
if ( !**heap_cur )
_bitreset( bit_cur, pixel_val&0x1f );
#endif
if ( pixel_val < comptr[-1].grey_level )
{
// check the stablity and push a new history, increase the grey level
if ( MSERStableCheck( comptr, params ) )
{
CvContour* contour = MSERToContour( comptr, storage );
contour->color = color;
cvSeqPush( contours, &contour );
}
MSERNewHistory( comptr, histptr );
comptr[0].grey_level = pixel_val;
histptr++;
} else {
// keep merging top two comp in stack until the grey level >= pixel_val
for ( ; ; )
{
comptr--;
MSERMergeComp( comptr+1, comptr, comptr, histptr );
histptr++;
if ( pixel_val <= comptr[0].grey_level )
break;
if ( pixel_val < comptr[-1].grey_level )
{
// check the stablity here otherwise it wouldn't be an ER
if ( MSERStableCheck( comptr, params ) )
{
CvContour* contour = MSERToContour( comptr, storage );
contour->color = color;
cvSeqPush( contours, &contour );
}
MSERNewHistory( comptr, histptr );
comptr[0].grey_level = pixel_val;
histptr++;
break;
}
}
}
} else
break;
}
}
}
static void extractMSER_8UC1( CvMat* src,
CvMat* mask,
CvSeq* contours,
CvMemStorage* storage,
MSERParams params )
{
int step = 8;
int stepgap = 3;
while ( step < src->step+2 )
{
step <<= 1;
stepgap++;
}
int stepmask = step-1;
// to speedup the process, make the width to be 2^N
CvMat* img = cvCreateMat( src->rows+2, step, CV_32SC1 );
int* ioptr = img->data.i+step+1;
int* imgptr;
// pre-allocate boundary heap
int** heap = (int**)cvAlloc( (src->rows*src->cols+256)*sizeof(heap[0]) );
int** heap_start[256];
heap_start[0] = heap;
// pre-allocate linked point and grow history
LinkedPoint* pts = (LinkedPoint*)cvAlloc( src->rows*src->cols*sizeof(pts[0]) );
MSERGrowHistory* history = (MSERGrowHistory*)cvAlloc( src->rows*src->cols*sizeof(history[0]) );
MSERConnectedComp comp[257];
// darker to brighter (MSER-)
imgptr = preprocessMSER_8UC1( img, heap_start, src, mask );
extractMSER_8UC1_Pass( ioptr, imgptr, heap_start, pts, history, comp, step, stepmask, stepgap, params, -1, contours, storage );
// brighter to darker (MSER+)
imgptr = preprocessMSER_8UC1( img, heap_start, src, mask );
extractMSER_8UC1_Pass( ioptr, imgptr, heap_start, pts, history, comp, step, stepmask, stepgap, params, 1, contours, storage );
// clean up
cvFree( &history );
cvFree( &heap );
cvFree( &pts );
cvReleaseMat( &img );
}
struct MSCRNode;
struct TempMSCR
{
MSCRNode* head;
MSCRNode* tail;
double m; // the margin used to prune area later
int size;
};
struct MSCRNode
{
MSCRNode* shortcut;
// to make the finding of root less painful
MSCRNode* prev;
MSCRNode* next;
// a point double-linked list
TempMSCR* tmsr;
// the temporary msr (set to NULL at every re-initialise)
TempMSCR* gmsr;
// the global msr (once set, never to NULL)
int index;
// the index of the node, at this point, it should be x at the first 16-bits, and y at the last 16-bits.
int rank;
int reinit;
int size, sizei;
double dt, di;
double s;
};
struct MSCREdge
{
double chi;
MSCRNode* left;
MSCRNode* right;
};
static double ChiSquaredDistance( uchar* x, uchar* y )
{
return (double)((x[0]-y[0])*(x[0]-y[0]))/(double)(x[0]+y[0]+1e-10)+
(double)((x[1]-y[1])*(x[1]-y[1]))/(double)(x[1]+y[1]+1e-10)+
(double)((x[2]-y[2])*(x[2]-y[2]))/(double)(x[2]+y[2]+1e-10);
}
static void initMSCRNode( MSCRNode* node )
{
node->gmsr = node->tmsr = NULL;
node->reinit = 0xffff;
node->rank = 0;
node->sizei = node->size = 1;
node->prev = node->next = node->shortcut = node;
}
// the preprocess to get the edge list with proper gaussian blur
static int preprocessMSER_8UC3( MSCRNode* node,
MSCREdge* edge,
double* total,
CvMat* src,
CvMat* mask,
CvMat* dx,
CvMat* dy,
int Ne,
int edgeBlurSize )
{
int srccpt = src->step-src->cols*3;
uchar* srcptr = src->data.ptr;
uchar* lastptr = src->data.ptr+3;
double* dxptr = dx->data.db;
for ( int i = 0; i < src->rows; i++ )
{
for ( int j = 0; j < src->cols-1; j++ )
{
*dxptr = ChiSquaredDistance( srcptr, lastptr );
dxptr++;
srcptr += 3;
lastptr += 3;
}
srcptr += srccpt+3;
lastptr += srccpt+3;
}
srcptr = src->data.ptr;
lastptr = src->data.ptr+src->step;
double* dyptr = dy->data.db;
for ( int i = 0; i < src->rows-1; i++ )
{
for ( int j = 0; j < src->cols; j++ )
{
*dyptr = ChiSquaredDistance( srcptr, lastptr );
dyptr++;
srcptr += 3;
lastptr += 3;
}
srcptr += srccpt;
lastptr += srccpt;
}
// get dx and dy and blur it
if ( edgeBlurSize >= 1 )
{
cvSmooth( dx, dx, CV_GAUSSIAN, edgeBlurSize, edgeBlurSize );
cvSmooth( dy, dy, CV_GAUSSIAN, edgeBlurSize, edgeBlurSize );
}
dxptr = dx->data.db;
dyptr = dy->data.db;
// assian dx, dy to proper edge list and initialize mscr node
// the nasty code here intended to avoid extra loops
if ( mask )
{
Ne = 0;
int maskcpt = mask->step-mask->cols+1;
uchar* maskptr = mask->data.ptr;
MSCRNode* nodeptr = node;
initMSCRNode( nodeptr );
nodeptr->index = 0;
*total += edge->chi = *dxptr;
if ( maskptr[0] && maskptr[1] )
{
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
Ne++;
}
dxptr++;
nodeptr++;
maskptr++;
for ( int i = 1; i < src->cols-1; i++ )
{
initMSCRNode( nodeptr );
nodeptr->index = i;
if ( maskptr[0] && maskptr[1] )
{
*total += edge->chi = *dxptr;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
Ne++;
}
dxptr++;
nodeptr++;
maskptr++;
}
initMSCRNode( nodeptr );
nodeptr->index = src->cols-1;
nodeptr++;
maskptr += maskcpt;
for ( int i = 1; i < src->rows-1; i++ )
{
initMSCRNode( nodeptr );
nodeptr->index = i<<16;
if ( maskptr[0] )
{
if ( maskptr[-mask->step] )
{
*total += edge->chi = *dyptr;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
Ne++;
}
if ( maskptr[1] )
{
*total += edge->chi = *dxptr;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
Ne++;
}
}
dyptr++;
dxptr++;
nodeptr++;
maskptr++;
for ( int j = 1; j < src->cols-1; j++ )
{
initMSCRNode( nodeptr );
nodeptr->index = (i<<16)|j;
if ( maskptr[0] )
{
if ( maskptr[-mask->step] )
{
*total += edge->chi = *dyptr;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
Ne++;
}
if ( maskptr[1] )
{
*total += edge->chi = *dxptr;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
Ne++;
}
}
dyptr++;
dxptr++;
nodeptr++;
maskptr++;
}
initMSCRNode( nodeptr );
nodeptr->index = (i<<16)|(src->cols-1);
if ( maskptr[0] && maskptr[-mask->step] )
{
*total += edge->chi = *dyptr;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
Ne++;
}
dyptr++;
nodeptr++;
maskptr += maskcpt;
}
initMSCRNode( nodeptr );
nodeptr->index = (src->rows-1)<<16;
if ( maskptr[0] )
{
if ( maskptr[1] )
{
*total += edge->chi = *dxptr;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
Ne++;
}
if ( maskptr[-mask->step] )
{
*total += edge->chi = *dyptr;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
Ne++;
}
}
dxptr++;
dyptr++;
nodeptr++;
maskptr++;
for ( int i = 1; i < src->cols-1; i++ )
{
initMSCRNode( nodeptr );
nodeptr->index = ((src->rows-1)<<16)|i;
if ( maskptr[0] )
{
if ( maskptr[1] )
{
*total += edge->chi = *dxptr;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
Ne++;
}
if ( maskptr[-mask->step] )
{
*total += edge->chi = *dyptr;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
Ne++;
}
}
dxptr++;
dyptr++;
nodeptr++;
maskptr++;
}
initMSCRNode( nodeptr );
nodeptr->index = ((src->rows-1)<<16)|(src->cols-1);
if ( maskptr[0] && maskptr[-mask->step] )
{
*total += edge->chi = *dyptr;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
Ne++;
}
} else {
MSCRNode* nodeptr = node;
initMSCRNode( nodeptr );
nodeptr->index = 0;
*total += edge->chi = *dxptr;
dxptr++;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
nodeptr++;
for ( int i = 1; i < src->cols-1; i++ )
{
initMSCRNode( nodeptr );
nodeptr->index = i;
*total += edge->chi = *dxptr;
dxptr++;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
nodeptr++;
}
initMSCRNode( nodeptr );
nodeptr->index = src->cols-1;
nodeptr++;
for ( int i = 1; i < src->rows-1; i++ )
{
initMSCRNode( nodeptr );
nodeptr->index = i<<16;
*total += edge->chi = *dyptr;
dyptr++;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
*total += edge->chi = *dxptr;
dxptr++;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
nodeptr++;
for ( int j = 1; j < src->cols-1; j++ )
{
initMSCRNode( nodeptr );
nodeptr->index = (i<<16)|j;
*total += edge->chi = *dyptr;
dyptr++;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
*total += edge->chi = *dxptr;
dxptr++;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
nodeptr++;
}
initMSCRNode( nodeptr );
nodeptr->index = (i<<16)|(src->cols-1);
*total += edge->chi = *dyptr;
dyptr++;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
nodeptr++;
}
initMSCRNode( nodeptr );
nodeptr->index = (src->rows-1)<<16;
*total += edge->chi = *dxptr;
dxptr++;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
*total += edge->chi = *dyptr;
dyptr++;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
nodeptr++;
for ( int i = 1; i < src->cols-1; i++ )
{
initMSCRNode( nodeptr );
nodeptr->index = ((src->rows-1)<<16)|i;
*total += edge->chi = *dxptr;
dxptr++;
edge->left = nodeptr;
edge->right = nodeptr+1;
edge++;
*total += edge->chi = *dyptr;
dyptr++;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
edge++;
nodeptr++;
}
initMSCRNode( nodeptr );
nodeptr->index = ((src->rows-1)<<16)|(src->cols-1);
*total += edge->chi = *dyptr;
edge->left = nodeptr-src->cols;
edge->right = nodeptr;
}
return Ne;
}
#define cmp_mscr_edge(edge1, edge2) \
((edge1).chi < (edge2).chi)
static CV_IMPLEMENT_QSORT( QuickSortMSCREdge, MSCREdge, cmp_mscr_edge )
// to find the root of one region
static MSCRNode* findMSCR( MSCRNode* x )
{
MSCRNode* prev = x;
MSCRNode* next;
for ( ; ; )
{
next = x->shortcut;
x->shortcut = prev;
if ( next == x ) break;
prev= x;
x = next;
}
MSCRNode* root = x;
for ( ; ; )
{
prev = x->shortcut;
x->shortcut = root;
if ( prev == x ) break;
x = prev;
}
return root;
}
// the stable mscr should be:
// bigger than minArea and smaller than maxArea
// differ from its ancestor more than minDiversity
static bool MSCRStableCheck( MSCRNode* x, MSERParams params )
{
if ( x->size <= params.minArea || x->size >= params.maxArea )
return 0;
if ( x->gmsr == NULL )
return 1;
double div = (double)(x->size-x->gmsr->size)/(double)x->size;
return div > params.minDiversity;
}
static void
extractMSER_8UC3( CvMat* src,
CvMat* mask,
CvSeq* contours,
CvMemStorage* storage,
MSERParams params )
{
MSCRNode* map = (MSCRNode*)cvAlloc( src->cols*src->rows*sizeof(map[0]) );
int Ne = src->cols*src->rows*2-src->cols-src->rows;
MSCREdge* edge = (MSCREdge*)cvAlloc( Ne*sizeof(edge[0]) );
TempMSCR* mscr = (TempMSCR*)cvAlloc( src->cols*src->rows*sizeof(mscr[0]) );
double emean = 0;
CvMat* dx = cvCreateMat( src->rows, src->cols-1, CV_64FC1 );
CvMat* dy = cvCreateMat( src->rows-1, src->cols, CV_64FC1 );
Ne = preprocessMSER_8UC3( map, edge, &emean, src, mask, dx, dy, Ne, params.edgeBlurSize );
emean = emean / (double)Ne;
QuickSortMSCREdge( edge, Ne, 0 );
MSCREdge* edge_ub = edge+Ne;
MSCREdge* edgeptr = edge;
TempMSCR* mscrptr = mscr;
// the evolution process
for ( int i = 0; i < params.maxEvolution; i++ )
{
double k = (double)i/(double)params.maxEvolution*(TABLE_SIZE-1);
int ti = cvFloor(k);
double reminder = k-ti;
double thres = emean*(chitab3[ti]*(1-reminder)+chitab3[ti+1]*reminder);
// to process all the edges in the list that chi < thres
while ( edgeptr < edge_ub && edgeptr->chi < thres )
{
MSCRNode* lr = findMSCR( edgeptr->left );
MSCRNode* rr = findMSCR( edgeptr->right );
// get the region root (who is responsible)
if ( lr != rr )
{
// rank idea take from: N-tree Disjoint-Set Forests for Maximally Stable Extremal Regions
if ( rr->rank > lr->rank )
{
MSCRNode* tmp;
CV_SWAP( lr, rr, tmp );
} else if ( lr->rank == rr->rank ) {
// at the same rank, we will compare the size
if ( lr->size > rr->size )
{
MSCRNode* tmp;
CV_SWAP( lr, rr, tmp );
}
lr->rank++;
}
rr->shortcut = lr;
lr->size += rr->size;
// join rr to the end of list lr (lr is a endless double-linked list)
lr->prev->next = rr;
lr->prev = rr->prev;
rr->prev->next = lr;
rr->prev = lr;
// area threshold force to reinitialize
if ( lr->size > (lr->size-rr->size)*params.areaThreshold )
{
lr->sizei = lr->size;
lr->reinit = i;
if ( lr->tmsr != NULL )
{
lr->tmsr->m = lr->dt-lr->di;
lr->tmsr = NULL;
}
lr->di = edgeptr->chi;
lr->s = 1e10;
}
lr->dt = edgeptr->chi;
if ( i > lr->reinit )
{
double s = (double)(lr->size-lr->sizei)/(lr->dt-lr->di);
if ( s < lr->s )
{
// skip the first one and check stablity
if ( i > lr->reinit+1 && MSCRStableCheck( lr, params ) )
{
if ( lr->tmsr == NULL )
{
lr->gmsr = lr->tmsr = mscrptr;
mscrptr++;
}
lr->tmsr->size = lr->size;
lr->tmsr->head = lr;
lr->tmsr->tail = lr->prev;
lr->tmsr->m = 0;
}
lr->s = s;
}
}
}
edgeptr++;
}
if ( edgeptr >= edge_ub )
break;
}
for ( TempMSCR* ptr = mscr; ptr < mscrptr; ptr++ )
// to prune area with margin less than minMargin
if ( ptr->m > params.minMargin )
{
CvSeq* _contour = cvCreateSeq( CV_SEQ_KIND_GENERIC|CV_32SC2, sizeof(CvContour), sizeof(CvPoint), storage );
cvSeqPushMulti( _contour, 0, ptr->size );
MSCRNode* lpt = ptr->head;
for ( int i = 0; i < ptr->size; i++ )
{
CvPoint* pt = CV_GET_SEQ_ELEM( CvPoint, _contour, i );
pt->x = (lpt->index)&0xffff;
pt->y = (lpt->index)>>16;
lpt = lpt->next;
}
CvContour* contour = (CvContour*)_contour;
cvBoundingRect( contour );
contour->color = 0;
cvSeqPush( contours, &contour );
}
cvReleaseMat( &dx );
cvReleaseMat( &dy );
cvFree( &mscr );
cvFree( &edge );
cvFree( &map );
}
static void
extractMSER( CvArr* _img,
CvArr* _mask,
CvSeq** _contours,
CvMemStorage* storage,
MSERParams params )
{
CvMat srchdr, *src = cvGetMat( _img, &srchdr );
CvMat maskhdr, *mask = _mask ? cvGetMat( _mask, &maskhdr ) : 0;
CvSeq* contours = 0;
CV_Assert(src != 0);
CV_Assert(CV_MAT_TYPE(src->type) == CV_8UC1 || CV_MAT_TYPE(src->type) == CV_8UC3);
CV_Assert(mask == 0 || (CV_ARE_SIZES_EQ(src, mask) && CV_MAT_TYPE(mask->type) == CV_8UC1));
CV_Assert(storage != 0);
contours = *_contours = cvCreateSeq( 0, sizeof(CvSeq), sizeof(CvSeq*), storage );
// choose different method for different image type
// for grey image, it is: Linear Time Maximally Stable Extremal Regions
// for color image, it is: Maximally Stable Colour Regions for Recognition and Matching
switch ( CV_MAT_TYPE(src->type) )
{
case CV_8UC1:
extractMSER_8UC1( src, mask, contours, storage, params );
break;
case CV_8UC3:
extractMSER_8UC3( src, mask, contours, storage, params );
break;
}
}
MSER::MSER( int _delta, int _min_area, int _max_area,
double _max_variation, double _min_diversity,
int _max_evolution, double _area_threshold,
double _min_margin, int _edge_blur_size )
: delta(_delta), minArea(_min_area), maxArea(_max_area),
maxVariation(_max_variation), minDiversity(_min_diversity),
maxEvolution(_max_evolution), areaThreshold(_area_threshold),
minMargin(_min_margin), edgeBlurSize(_edge_blur_size)
{
}
void MSER::operator()( const Mat& image, vector<vector<Point> >& dstcontours, const Mat& mask ) const
{
CvMat _image = image, _mask, *pmask = 0;
if( mask.data )
pmask = &(_mask = mask);
MemStorage storage(cvCreateMemStorage(0));
Seq<CvSeq*> contours;
extractMSER( &_image, pmask, &contours.seq, storage,
MSERParams(delta, minArea, maxArea, maxVariation, minDiversity,
maxEvolution, areaThreshold, minMargin, edgeBlurSize));
SeqIterator<CvSeq*> it = contours.begin();
size_t i, ncontours = contours.size();
dstcontours.resize(ncontours);
for( i = 0; i < ncontours; i++, ++it )
Seq<Point>(*it).copyTo(dstcontours[i]);
}
void MserFeatureDetector::detectImpl( const Mat& image, vector<KeyPoint>& keypoints, const Mat& mask ) const
{
vector<vector<Point> > msers;
(*this)(image, msers, mask);
vector<vector<Point> >::const_iterator contour_it = msers.begin();
Rect r(0, 0, image.cols, image.rows);
for( ; contour_it != msers.end(); ++contour_it )
{
// TODO check transformation from MSER region to KeyPoint
RotatedRect rect = fitEllipse(Mat(*contour_it));
float diam = sqrt(rect.size.height*rect.size.width);
if( diam > std::numeric_limits<float>::epsilon() && r.contains(rect.center) )
keypoints.push_back( KeyPoint(rect.center, diam) );
}
}
}