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41 
42 #include "_cvaux.h"
43 
44 /****************************************************************************************\
45     The code below is some modification of Stan Birchfield's algorithm described in:
46 
47     Depth Discontinuities by Pixel-to-Pixel Stereo
48     Stan Birchfield and Carlo Tomasi
49     International Journal of Computer Vision,
50     35(3): 269-293, December 1999.
51 
52     This implementation uses different cost function that results in
53     O(pixPerRow*maxDisparity) complexity of dynamic programming stage versus
54     O(pixPerRow*log(pixPerRow)*maxDisparity) in the above paper.
55 \****************************************************************************************/
56 
57 /****************************************************************************************\
58 *       Find stereo correspondence by dynamic programming algorithm                      *
59 \****************************************************************************************/
60 #define ICV_DP_STEP_LEFT  0
61 #define ICV_DP_STEP_UP    1
62 #define ICV_DP_STEP_DIAG  2
63 
64 #define ICV_BIRCH_DIFF_LUM 5
65 
66 #define ICV_MAX_DP_SUM_VAL (INT_MAX/4)
67 
68 typedef struct _CvDPCell
69 {
70     uchar  step; //local-optimal step
71     int    sum;  //current sum
72 }_CvDPCell;
73 
74 typedef struct _CvRightImData
75 {
76     uchar min_val, max_val;
77 } _CvRightImData;
78 
79 #define CV_IMAX3(a,b,c) ((temp3 = (a) >= (b) ? (a) : (b)),(temp3 >= (c) ? temp3 : (c)))
80 #define CV_IMIN3(a,b,c) ((temp3 = (a) <= (b) ? (a) : (b)),(temp3 <= (c) ? temp3 : (c)))
81 
icvFindStereoCorrespondenceByBirchfieldDP(uchar * src1,uchar * src2,uchar * disparities,CvSize size,int widthStep,int maxDisparity,float _param1,float _param2,float _param3,float _param4,float _param5)82 void icvFindStereoCorrespondenceByBirchfieldDP( uchar* src1, uchar* src2,
83                                                 uchar* disparities,
84                                                 CvSize size, int widthStep,
85                                                 int    maxDisparity,
86                                                 float  _param1, float _param2,
87                                                 float  _param3, float _param4,
88                                                 float  _param5 )
89 {
90     int     x, y, i, j, temp3;
91     int     d, s;
92     int     dispH =  maxDisparity + 3;
93     uchar  *dispdata;
94     int     imgW = size.width;
95     int     imgH = size.height;
96     uchar   val, prevval, prev, curr;
97     int     min_val;
98     uchar*  dest = disparities;
99     int param1 = cvRound(_param1);
100     int param2 = cvRound(_param2);
101     int param3 = cvRound(_param3);
102     int param4 = cvRound(_param4);
103     int param5 = cvRound(_param5);
104 
105     #define CELL(d,x)   cells[(d)+(x)*dispH]
106 
107     uchar*              dsi = (uchar*)cvAlloc(sizeof(uchar)*imgW*dispH);
108     uchar*              edges = (uchar*)cvAlloc(sizeof(uchar)*imgW*imgH);
109     _CvDPCell*          cells = (_CvDPCell*)cvAlloc(sizeof(_CvDPCell)*imgW*MAX(dispH,(imgH+1)/2));
110     _CvRightImData*     rData = (_CvRightImData*)cvAlloc(sizeof(_CvRightImData)*imgW);
111     int*                reliabilities = (int*)cells;
112 
113     for( y = 0; y < imgH; y++ )
114     {
115         uchar* srcdata1 = src1 + widthStep * y;
116         uchar* srcdata2 = src2 + widthStep * y;
117 
118         //init rData
119         prevval = prev = srcdata2[0];
120         for( j = 1; j < imgW; j++ )
121         {
122             curr = srcdata2[j];
123             val = (uchar)((curr + prev)>>1);
124             rData[j-1].max_val = (uchar)CV_IMAX3( val, prevval, prev );
125             rData[j-1].min_val = (uchar)CV_IMIN3( val, prevval, prev );
126             prevval = val;
127             prev = curr;
128         }
129         rData[j-1] = rData[j-2];//last elem
130 
131         // fill dissimularity space image
132         for( i = 1; i <= maxDisparity + 1; i++ )
133         {
134             dsi += imgW;
135             rData--;
136             for( j = i - 1; j < imgW - 1; j++ )
137             {
138                 int t;
139                 if( (t = srcdata1[j] - rData[j+1].max_val) >= 0 )
140                 {
141                     dsi[j] = (uchar)t;
142                 }
143                 else if( (t = rData[j+1].min_val - srcdata1[j]) >= 0 )
144                 {
145                     dsi[j] = (uchar)t;
146                 }
147                 else
148                 {
149                     dsi[j] = 0;
150                 }
151             }
152         }
153         dsi -= (maxDisparity+1)*imgW;
154         rData += maxDisparity+1;
155 
156         //intensity gradients image construction
157         //left row
158         edges[y*imgW] = edges[y*imgW+1] = edges[y*imgW+2] = 2;
159         edges[y*imgW+imgW-1] = edges[y*imgW+imgW-2] = edges[y*imgW+imgW-3] = 1;
160         for( j = 3; j < imgW-4; j++ )
161         {
162             edges[y*imgW+j] = 0;
163 
164             if( ( CV_IMAX3( srcdata1[j-3], srcdata1[j-2], srcdata1[j-1] ) -
165                   CV_IMIN3( srcdata1[j-3], srcdata1[j-2], srcdata1[j-1] ) ) >= ICV_BIRCH_DIFF_LUM )
166             {
167                 edges[y*imgW+j] |= 1;
168             }
169             if( ( CV_IMAX3( srcdata2[j+3], srcdata2[j+2], srcdata2[j+1] ) -
170                   CV_IMIN3( srcdata2[j+3], srcdata2[j+2], srcdata2[j+1] ) ) >= ICV_BIRCH_DIFF_LUM )
171             {
172                 edges[y*imgW+j] |= 2;
173             }
174         }
175 
176         //find correspondence using dynamical programming
177         //init DP table
178         for( x = 0; x < imgW; x++ )
179         {
180             CELL(0,x).sum = CELL(dispH-1,x).sum = ICV_MAX_DP_SUM_VAL;
181             CELL(0,x).step = CELL(dispH-1,x).step = ICV_DP_STEP_LEFT;
182         }
183         for( d = 2; d < dispH; d++ )
184         {
185             CELL(d,d-2).sum = ICV_MAX_DP_SUM_VAL;
186             CELL(d,d-2).step = ICV_DP_STEP_UP;
187         }
188         CELL(1,0).sum  = 0;
189         CELL(1,0).step = ICV_DP_STEP_LEFT;
190 
191         for( x = 1; x < imgW; x++ )
192         {
193             int d = MIN( x + 1, maxDisparity + 1);
194             uchar* _edges = edges + y*imgW + x;
195             int e0 = _edges[0] & 1;
196             _CvDPCell* _cell = cells + x*dispH;
197 
198             do
199             {
200                 int s = dsi[d*imgW+x];
201                 int sum[3];
202 
203                 //check left step
204                 sum[0] = _cell[d-dispH].sum - param2;
205 
206                 //check up step
207                 if( _cell[d+1].step != ICV_DP_STEP_DIAG && e0 )
208                 {
209                     sum[1] = _cell[d+1].sum + param1;
210 
211                     if( _cell[d-1-dispH].step != ICV_DP_STEP_UP && (_edges[1-d] & 2) )
212                     {
213                         int t;
214 
215                         sum[2] = _cell[d-1-dispH].sum + param1;
216 
217                         t = sum[1] < sum[0];
218 
219                         //choose local-optimal pass
220                         if( sum[t] <= sum[2] )
221                         {
222                             _cell[d].step = (uchar)t;
223                             _cell[d].sum = sum[t] + s;
224                         }
225                         else
226                         {
227                             _cell[d].step = ICV_DP_STEP_DIAG;
228                             _cell[d].sum = sum[2] + s;
229                         }
230                     }
231                     else
232                     {
233                         if( sum[0] <= sum[1] )
234                         {
235                             _cell[d].step = ICV_DP_STEP_LEFT;
236                             _cell[d].sum = sum[0] + s;
237                         }
238                         else
239                         {
240                             _cell[d].step = ICV_DP_STEP_UP;
241                             _cell[d].sum = sum[1] + s;
242                         }
243                     }
244                 }
245                 else if( _cell[d-1-dispH].step != ICV_DP_STEP_UP && (_edges[1-d] & 2) )
246                 {
247                     sum[2] = _cell[d-1-dispH].sum + param1;
248                     if( sum[0] <= sum[2] )
249                     {
250                         _cell[d].step = ICV_DP_STEP_LEFT;
251                         _cell[d].sum = sum[0] + s;
252                     }
253                     else
254                     {
255                         _cell[d].step = ICV_DP_STEP_DIAG;
256                         _cell[d].sum = sum[2] + s;
257                     }
258                 }
259                 else
260                 {
261                     _cell[d].step = ICV_DP_STEP_LEFT;
262                     _cell[d].sum = sum[0] + s;
263                 }
264             }
265             while( --d );
266         }// for x
267 
268         //extract optimal way and fill disparity image
269         dispdata = dest + widthStep * y;
270 
271         //find min_val
272         min_val = ICV_MAX_DP_SUM_VAL;
273         for( i = 1; i <= maxDisparity + 1; i++ )
274         {
275             if( min_val > CELL(i,imgW-1).sum )
276             {
277                 d = i;
278                 min_val = CELL(i,imgW-1).sum;
279             }
280         }
281 
282         //track optimal pass
283         for( x = imgW - 1; x > 0; x-- )
284         {
285             dispdata[x] = (uchar)(d - 1);
286             while( CELL(d,x).step == ICV_DP_STEP_UP ) d++;
287             if ( CELL(d,x).step == ICV_DP_STEP_DIAG )
288             {
289                 s = x;
290                 while( CELL(d,x).step == ICV_DP_STEP_DIAG )
291                 {
292                     d--;
293                     x--;
294                 }
295                 for( i = x; i < s; i++ )
296                 {
297                     dispdata[i] = (uchar)(d-1);
298                 }
299             }
300         }//for x
301     }// for y
302 
303     //Postprocessing the Disparity Map
304 
305     //remove obvious errors in the disparity map
306     for( x = 0; x < imgW; x++ )
307     {
308         for( y = 1; y < imgH - 1; y++ )
309         {
310             if( dest[(y-1)*widthStep+x] == dest[(y+1)*widthStep+x] )
311             {
312                 dest[y*widthStep+x] = dest[(y-1)*widthStep+x];
313             }
314         }
315     }
316 
317     //compute intensity Y-gradients
318     for( x = 0; x < imgW; x++ )
319     {
320         for( y = 1; y < imgH - 1; y++ )
321         {
322             if( ( CV_IMAX3( src1[(y-1)*widthStep+x], src1[y*widthStep+x],
323                         src1[(y+1)*widthStep+x] ) -
324                   CV_IMIN3( src1[(y-1)*widthStep+x], src1[y*widthStep+x],
325                         src1[(y+1)*widthStep+x] ) ) >= ICV_BIRCH_DIFF_LUM )
326             {
327                 edges[y*imgW+x] |= 4;
328                 edges[(y+1)*imgW+x] |= 4;
329                 edges[(y-1)*imgW+x] |= 4;
330                 y++;
331             }
332         }
333     }
334 
335     //remove along any particular row, every gradient
336     //for which two adjacent columns do not agree.
337     for( y = 0; y < imgH; y++ )
338     {
339         prev = edges[y*imgW];
340         for( x = 1; x < imgW - 1; x++ )
341         {
342             curr = edges[y*imgW+x];
343             if( (curr & 4) &&
344                 ( !( prev & 4 ) ||
345                   !( edges[y*imgW+x+1] & 4 ) ) )
346             {
347                 edges[y*imgW+x] -= 4;
348             }
349             prev = curr;
350         }
351     }
352 
353     // define reliability
354     for( x = 0; x < imgW; x++ )
355     {
356         for( y = 1; y < imgH; y++ )
357         {
358             i = y - 1;
359             for( ; y < imgH && dest[y*widthStep+x] == dest[(y-1)*widthStep+x]; y++ )
360                 ;
361             s = y - i;
362             for( ; i < y; i++ )
363             {
364                 reliabilities[i*imgW+x] = s;
365             }
366         }
367     }
368 
369     //Y - propagate reliable regions
370     for( x = 0; x < imgW; x++ )
371     {
372         for( y = 0; y < imgH; y++ )
373         {
374             d = dest[y*widthStep+x];
375             if( reliabilities[y*imgW+x] >= param4 && !(edges[y*imgW+x] & 4) &&
376                 d > 0 )//highly || moderately
377             {
378                 disparities[y*widthStep+x] = (uchar)d;
379                 //up propagation
380                 for( i = y - 1; i >= 0; i-- )
381                 {
382                     if(  ( edges[i*imgW+x] & 4 ) ||
383                          ( dest[i*widthStep+x] < d &&
384                            reliabilities[i*imgW+x] >= param3 ) ||
385                          ( reliabilities[y*imgW+x] < param5 &&
386                            dest[i*widthStep+x] - 1 == d ) ) break;
387 
388                     disparities[i*widthStep+x] = (uchar)d;
389                 }
390 
391                 //down propagation
392                 for( i = y + 1; i < imgH; i++ )
393                 {
394                     if(  ( edges[i*imgW+x] & 4 ) ||
395                          ( dest[i*widthStep+x] < d &&
396                            reliabilities[i*imgW+x] >= param3 ) ||
397                          ( reliabilities[y*imgW+x] < param5 &&
398                            dest[i*widthStep+x] - 1 == d ) ) break;
399 
400                     disparities[i*widthStep+x] = (uchar)d;
401                 }
402                 y = i - 1;
403             }
404             else
405             {
406                 disparities[y*widthStep+x] = (uchar)d;
407             }
408         }
409     }
410 
411     // define reliability along X
412     for( y = 0; y < imgH; y++ )
413     {
414         for( x = 1; x < imgW; x++ )
415         {
416             i = x - 1;
417             for( ; x < imgW && dest[y*widthStep+x] == dest[y*widthStep+x-1]; x++ );
418             s = x - i;
419             for( ; i < x; i++ )
420             {
421                 reliabilities[y*imgW+i] = s;
422             }
423         }
424     }
425 
426     //X - propagate reliable regions
427     for( y = 0; y < imgH; y++ )
428     {
429         for( x = 0; x < imgW; x++ )
430         {
431             d = dest[y*widthStep+x];
432             if( reliabilities[y*imgW+x] >= param4 && !(edges[y*imgW+x] & 1) &&
433                 d > 0 )//highly || moderately
434             {
435                 disparities[y*widthStep+x] = (uchar)d;
436                 //up propagation
437                 for( i = x - 1; i >= 0; i-- )
438                 {
439                     if(  (edges[y*imgW+i] & 1) ||
440                          ( dest[y*widthStep+i] < d &&
441                            reliabilities[y*imgW+i] >= param3 ) ||
442                          ( reliabilities[y*imgW+x] < param5 &&
443                            dest[y*widthStep+i] - 1 == d ) ) break;
444 
445                     disparities[y*widthStep+i] = (uchar)d;
446                 }
447 
448                 //down propagation
449                 for( i = x + 1; i < imgW; i++ )
450                 {
451                     if(  (edges[y*imgW+i] & 1) ||
452                          ( dest[y*widthStep+i] < d &&
453                            reliabilities[y*imgW+i] >= param3 ) ||
454                          ( reliabilities[y*imgW+x] < param5 &&
455                            dest[y*widthStep+i] - 1 == d ) ) break;
456 
457                     disparities[y*widthStep+i] = (uchar)d;
458                 }
459                 x = i - 1;
460             }
461             else
462             {
463                 disparities[y*widthStep+x] = (uchar)d;
464             }
465         }
466     }
467 
468     //release resources
469     cvFree( &dsi );
470     cvFree( &edges );
471     cvFree( &cells );
472     cvFree( &rData );
473 }
474 
475 
476 /*F///////////////////////////////////////////////////////////////////////////
477 //
478 //    Name:    cvFindStereoCorrespondence
479 //    Purpose: find stereo correspondence on stereo-pair
480 //    Context:
481 //    Parameters:
482 //      leftImage - left image of stereo-pair (format 8uC1).
483 //      rightImage - right image of stereo-pair (format 8uC1).
484 //      mode -mode of correspondance retrieval (now CV_RETR_DP_BIRCHFIELD only)
485 //      dispImage - destination disparity image
486 //      maxDisparity - maximal disparity
487 //      param1, param2, param3, param4, param5 - parameters of algorithm
488 //    Returns:
489 //    Notes:
490 //      Images must be rectified.
491 //      All images must have format 8uC1.
492 //F*/
493 CV_IMPL void
cvFindStereoCorrespondence(const CvArr * leftImage,const CvArr * rightImage,int mode,CvArr * depthImage,int maxDisparity,double param1,double param2,double param3,double param4,double param5)494 cvFindStereoCorrespondence(
495                    const  CvArr* leftImage, const  CvArr* rightImage,
496                    int     mode,
497                    CvArr*  depthImage,
498                    int     maxDisparity,
499                    double  param1, double  param2, double  param3,
500                    double  param4, double  param5  )
501 {
502     CV_FUNCNAME( "cvFindStereoCorrespondence" );
503 
504     __BEGIN__;
505 
506     CvMat  *src1, *src2;
507     CvMat  *dst;
508     CvMat  src1_stub, src2_stub, dst_stub;
509     int    coi;
510 
511     CV_CALL( src1 = cvGetMat( leftImage, &src1_stub, &coi ));
512     if( coi ) CV_ERROR( CV_BadCOI, "COI is not supported by the function" );
513     CV_CALL( src2 = cvGetMat( rightImage, &src2_stub, &coi ));
514     if( coi ) CV_ERROR( CV_BadCOI, "COI is not supported by the function" );
515     CV_CALL( dst = cvGetMat( depthImage, &dst_stub, &coi ));
516     if( coi ) CV_ERROR( CV_BadCOI, "COI is not supported by the function" );
517 
518     // check args
519     if( CV_MAT_TYPE( src1->type ) != CV_8UC1 ||
520         CV_MAT_TYPE( src2->type ) != CV_8UC1 ||
521         CV_MAT_TYPE( dst->type ) != CV_8UC1) CV_ERROR(CV_StsUnsupportedFormat,
522                         "All images must be single-channel and have 8u" );
523 
524     if( !CV_ARE_SIZES_EQ( src1, src2 ) || !CV_ARE_SIZES_EQ( src1, dst ) )
525             CV_ERROR( CV_StsUnmatchedSizes, "" );
526 
527     if( maxDisparity <= 0 || maxDisparity >= src1->width || maxDisparity > 255 )
528         CV_ERROR(CV_StsOutOfRange,
529                  "parameter /maxDisparity/ is out of range");
530 
531     if( mode == CV_DISPARITY_BIRCHFIELD )
532     {
533         if( param1 == CV_UNDEF_SC_PARAM ) param1 = CV_IDP_BIRCHFIELD_PARAM1;
534         if( param2 == CV_UNDEF_SC_PARAM ) param2 = CV_IDP_BIRCHFIELD_PARAM2;
535         if( param3 == CV_UNDEF_SC_PARAM ) param3 = CV_IDP_BIRCHFIELD_PARAM3;
536         if( param4 == CV_UNDEF_SC_PARAM ) param4 = CV_IDP_BIRCHFIELD_PARAM4;
537         if( param5 == CV_UNDEF_SC_PARAM ) param5 = CV_IDP_BIRCHFIELD_PARAM5;
538 
539         CV_CALL( icvFindStereoCorrespondenceByBirchfieldDP( src1->data.ptr,
540             src2->data.ptr, dst->data.ptr,
541             cvGetMatSize( src1 ), src1->step,
542             maxDisparity, (float)param1, (float)param2, (float)param3,
543             (float)param4, (float)param5 ) );
544     }
545     else
546     {
547         CV_ERROR( CV_StsBadArg, "Unsupported mode of function" );
548     }
549 
550     __END__;
551 }
552 
553 /* End of file. */
554 
555