Getting to Know OpenCV
主講人：虞台文
Content
Basic StructuresArrays, Matrices, and ImagesMatrix and Image OperatorsDrawing ThingsDrawing TextData Persistence
Getting to Know OpenCV
Basic Structures
Basic Structures (Point)
typedef struct CvPoint{ int x; int y;} CvPoint;
typedef struct CvPoint{ int x; int y;} CvPoint;
CV_INLINE CvPoint cvPoint(int x, int y){ CvPoint p;
p.x = x; p.y = y;
return p;}
CV_INLINE CvPoint cvPoint(int x, int y){ CvPoint p;
p.x = x; p.y = y;
return p;}
CvPoint pt1;
pt1.x = 20;pt1.y = 50
CvPoint pt1;
pt1.x = 20;pt1.y = 50
CvPoint pt2 = cvPoint(20, 50);CvPoint pt2 = cvPoint(20, 50);
cxtypes.h
Basic Structures (Point)
typedef struct CvPoint{ int x; int y;} CvPoint;
typedef struct CvPoint{ int x; int y;} CvPoint;
cxtypes.h
typedef struct CvPoint2D32f{ float x; float y;} CvPoint2D32f;
typedef struct CvPoint2D32f{ float x; float y;} CvPoint2D32f;
typedef struct CvPoint2D64f{ double x; double y;} CvPoint2D64f;
typedef struct CvPoint2D64f{ double x; double y;} CvPoint2D64f;
typedef struct CvPoint3D32f{ float x; float y; float z;} CvPoint3D32f;
typedef struct CvPoint3D32f{ float x; float y; float z;} CvPoint3D32f;
typedef struct CvPoint3D64f{ double x; double y; double z;} CvPoint3D64f;
typedef struct CvPoint3D64f{ double x; double y; double z;} CvPoint3D64f;
Basic Structures (Size)
typedef struct CvSize{ int width; int height;} CvSize;
typedef struct CvSize{ int width; int height;} CvSize;
cxtypes.h
typedef struct CvSize2D32f{ float width; float height;} CvSize2D32f
typedef struct CvSize2D32f{ float width; float height;} CvSize2D32f
typedef struct CvRect{ int x; int y; int width; int height;} CvRect;
typedef struct CvRect{ int x; int y; int width; int height;} CvRect;
Basic Structures (Scalar)
typedef struct CvScalar{ double val[4];} CvScalar;
typedef struct CvScalar{ double val[4];} CvScalar;
cxtypes.h
/* Constructor:initializes val[0] with val0, val[1] with val1, etc.*/inline CvScalar cvScalar( double val0, double val1=0, double val2=0, double val3=0 );/* Constructor:initializes all of val[0]...val[3] with val0123*/inline CvScalar cvScalarAll( double val0123 );
/* Constructor:initializes val[0] with val0, and all of val[1]...val[3] with zeros*/inline CvScalar cvRealScalar( double val0 );
/* Constructor:initializes val[0] with val0, val[1] with val1, etc.*/inline CvScalar cvScalar( double val0, double val1=0, double val2=0, double val3=0 );/* Constructor:initializes all of val[0]...val[3] with val0123*/inline CvScalar cvScalarAll( double val0123 );
/* Constructor:initializes val[0] with val0, and all of val[1]...val[3] with zeros*/inline CvScalar cvRealScalar( double val0 );
Getting to Know OpenCV
Arrays, Matrices, and Images
ArrayMatrixImage
cxtypes.h
Even though OpenCV is implemented in C, the structures used in OpenCV have an object-oriented design; in effect, IplImage is derived from CvMat, which is derived from CvArr
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
CV_<bit_depth>(S|U|F)C<number_of_channels>CV_<bit_depth>(S|U|F)C<number_of_channels>
Examples
CV_8UC3
CV_32FC1 32-bit floats
unsigned integer 8-bit triplets
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
the length of a row in bytes
a pointer to a data array
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
the height (rows) and width (cols) of the matrix
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
Matrix Header
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
Some Matrix Operators:// Create a new rows by cols matrix of type ‘type’CvMat* cvCreateMat(int rows, int cols, int type)
// Creates only matrix header without allocating dataCvMat* cvCreateMatHeader(int rows, int cols, int type) // allocates image, matrix or multi-dimensional array datavoid cvCreateData(CvArr* arr)
// Initialize header on existing CvMat structureCvMat* cvInitMatHeader(CvMat* mat,
int rows, int cols, int type, void* data=NULL, int step=CV_AUTOSTEP)
// Like cvInitMatHeader() but allocates CvMat as wellCvMat cvMat(int rows, int cols, int type, void* data=NULL);// Allocate a new matrix just like the matrix ‘mat’CvMat* cvCloneMat(const cvMat* mat);
// Free the matrix ‘mat’, both header and datavoid cvReleaseMat(CvMat** mat);
Some Matrix Operators:// Create a new rows by cols matrix of type ‘type’CvMat* cvCreateMat(int rows, int cols, int type)
// Creates only matrix header without allocating dataCvMat* cvCreateMatHeader(int rows, int cols, int type) // allocates image, matrix or multi-dimensional array datavoid cvCreateData(CvArr* arr)
// Initialize header on existing CvMat structureCvMat* cvInitMatHeader(CvMat* mat,
int rows, int cols, int type, void* data=NULL, int step=CV_AUTOSTEP)
// Like cvInitMatHeader() but allocates CvMat as wellCvMat cvMat(int rows, int cols, int type, void* data=NULL);// Allocate a new matrix just like the matrix ‘mat’CvMat* cvCloneMat(const cvMat* mat);
// Free the matrix ‘mat’, both header and datavoid cvReleaseMat(CvMat** mat);
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
Accessing matrix elements
Easy way:
CV_MAT_ELEM()
CV_MAT_ELEM_PTR()
CvMat* mat = cvCreateMat( 5, 5, CV_32FC1 );int i, j;float sum = 0.0f;
for(i=0; i<5; i++) for(j=0; j<5; j++) CV_MAT_ELEM(*mat, float, i, j) = (float) i + j;
for(i=0; i<5; i++) for(j=0; j<5; j++) sum += CV_MAT_ELEM(*mat, float, i, j);
CvMat* mat = cvCreateMat( 5, 5, CV_32FC1 );int i, j;float sum = 0.0f;
for(i=0; i<5; i++) for(j=0; j<5; j++) CV_MAT_ELEM(*mat, float, i, j) = (float) i + j;
for(i=0; i<5; i++) for(j=0; j<5; j++) sum += CV_MAT_ELEM(*mat, float, i, j);
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
Accessing matrix elements
Easy way:
CV_MAT_ELEM()
CV_MAT_ELEM_PTR()
CvMat* mat = cvCreateMat( 5, 5, CV_32FC1 );int i, j;float sum = 0.0f;
for(i=0; i<5; i++) for(j=0; j<5; j++) *((float*) CV_MAT_ELEM_PTR(*mat, i, j)) = (float) i + j;
for(i=0; i<5; i++) for(j=0; j<5; j++) sum += *((float*) CV_MAT_ELEM_PTR(*mat, i, j)) ;
CvMat* mat = cvCreateMat( 5, 5, CV_32FC1 );int i, j;float sum = 0.0f;
for(i=0; i<5; i++) for(j=0; j<5; j++) *((float*) CV_MAT_ELEM_PTR(*mat, i, j)) = (float) i + j;
for(i=0; i<5; i++) for(j=0; j<5; j++) sum += *((float*) CV_MAT_ELEM_PTR(*mat, i, j)) ;
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
Accessing matrix elements
Easy way:
CV_MAT_ELEM()
CV_MAT_ELEM_PTR()
Although these macros are easy to use, they may
not be the best way to access a matrix.Although these macros are easy to use, they may
not be the best way to access a matrix.
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
Accessing matrix elements
Hard way:
cvPtr?D()
cvGetReal?D()
cvGet?D()
cvSetReal?D()
cvSet?D()
cvmGet()
cvmSet()
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
Accessing matrix elements
Hard way:
cvPtr?D()
cvGetReal?D()
cvGet?D()
cvSetReal?D()
cvSet?D()
cvmGet()
cvmSet()
Using these pointer functions togain access to a particular point in the matrix and then use pointer arithmetic to move around in the matrix from there.
Using these pointer functions togain access to a particular point in the matrix and then use pointer arithmetic to move around in the matrix from there.
Ineffective
ArrayMatrixImagetypedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
typedef struct CvMat{ int type; int step; //# bytes per row
int* refcount; // internal use int hdr_refcount; // internal use
union{ uchar* ptr; short* s; int* i; float* fl; double* db; } data;
union{ int rows; int height; };
union{ int cols; int width; };} CvMat;
cxtypes.h
#include <stdio.h>#include <cv.h>#include <highgui.h>
float sum( CvMat* mat ) { float s = 0.0f; for( int row=0; row<mat->height; row++ ) { float* ptr = mat->data.fl + row * mat->step/4; for( int col=0; col<mat->width; col++ ) { s += *ptr++; } } return( s );};
int main(int argc, char** argv){ CvMat *mat = cvCreateMat(5,5,CV_32FC1); float element_3_2 = 7.7; *((float*)CV_MAT_ELEM_PTR( *mat, 3,2) ) = element_3_2; cvmSet(mat,4,4,0.5000); cvSetReal2D(mat,3,3,0.5000); float s = sum(mat); printf("%f\n",s); return 0;}
#include <stdio.h>#include <cv.h>#include <highgui.h>
float sum( CvMat* mat ) { float s = 0.0f; for( int row=0; row<mat->height; row++ ) { float* ptr = mat->data.fl + row * mat->step/4; for( int col=0; col<mat->width; col++ ) { s += *ptr++; } } return( s );};
int main(int argc, char** argv){ CvMat *mat = cvCreateMat(5,5,CV_32FC1); float element_3_2 = 7.7; *((float*)CV_MAT_ELEM_PTR( *mat, 3,2) ) = element_3_2; cvmSet(mat,4,4,0.5000); cvSetReal2D(mat,3,3,0.5000); float s = sum(mat); printf("%f\n",s); return 0;}
Accessing matrix elements
Right way:
ArrayMatrixImage
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
ArrayMatrixImage
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
• nSize - sizeof(IplImage)• ID - Version, always equals 0• nChannels - Number of channels. Most OpenCV functions support 1-4 channels.• alphaChannel - Ignored by OpenCV• depth - Pixel depth in bits. The supported depths are:
IPL_DEPTH_8U - Unsigned 8-bit integer
IPL_DEPTH_8S - Signed 8-bit integer
IPL_DEPTH_16U - Unsigned 16-bit integer
IPL_DEPTH_16S - Signed 16-bit integer
IPL_DEPTH_32S - Signed 32-bit integer
IPL_DEPTH_32F - Single-precision floating point
IPL_DEPTH_64F - Double-precision floating point
• nSize - sizeof(IplImage)• ID - Version, always equals 0• nChannels - Number of channels. Most OpenCV functions support 1-4 channels.• alphaChannel - Ignored by OpenCV• depth - Pixel depth in bits. The supported depths are:
IPL_DEPTH_8U - Unsigned 8-bit integer
IPL_DEPTH_8S - Signed 8-bit integer
IPL_DEPTH_16U - Unsigned 16-bit integer
IPL_DEPTH_16S - Signed 16-bit integer
IPL_DEPTH_32S - Signed 32-bit integer
IPL_DEPTH_32F - Single-precision floating point
IPL_DEPTH_64F - Double-precision floating point
ArrayMatrixImage
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
• colorModel - Ignored by OpenCV.
• channelSeq - Ignored by OpenCV
• dataOrder - 0 = IPL_DATA_ORDER_PIXEL 1 = IPL_DATA_ORDER_PLANE
• origin - 0 = IPL_ORIGIN_TL 1 = IPL_ORIGIN_BL
• align - OpenCV ignores this and uses widthStep instead.
• width - Image width in pixels
• height - Image height in pixels
• colorModel - Ignored by OpenCV.
• channelSeq - Ignored by OpenCV
• dataOrder - 0 = IPL_DATA_ORDER_PIXEL 1 = IPL_DATA_ORDER_PLANE
• origin - 0 = IPL_ORIGIN_TL 1 = IPL_ORIGIN_BL
• align - OpenCV ignores this and uses widthStep instead.
• width - Image width in pixels
• height - Image height in pixels
ArrayMatrixImage
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
• roi - Region Of Interest (ROI). If not NULL, only this image region will be processed.
• maskROI - Must be NULL in OpenCV
• imageId - Must be NULL in OpenCV
• tileInfo - Must be NULL in OpenCV
• roi - Region Of Interest (ROI). If not NULL, only this image region will be processed.
• maskROI - Must be NULL in OpenCV
• imageId - Must be NULL in OpenCV
• tileInfo - Must be NULL in OpenCV
ArrayMatrixImage
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
• imageSize - Image data size in bytes. For interleaved data, this equals image->height*image->widthStep
• imageData - A pointer to the aligned image data
• widthStep - The size of an aligned image row, in bytes
• BorderMode - Border completion mode, ignored by OpenCV
• BorderConst - Border completion mode, ignored by OpenCV
• imageDataOrigin - A pointer to the origin of the image data (not necessarily aligned). This is used for
image deallocation.
• imageSize - Image data size in bytes. For interleaved data, this equals image->height*image->widthStep
• imageData - A pointer to the aligned image data
• widthStep - The size of an aligned image row, in bytes
• BorderMode - Border completion mode, ignored by OpenCV
• BorderConst - Border completion mode, ignored by OpenCV
• imageDataOrigin - A pointer to the origin of the image data (not necessarily aligned). This is used for
image deallocation.
Accessing Image Data
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
typedef struct _IplImage {int nSize;int ID;int nChannels;int alphaChannel;int depth;char colorModel[4];char channelSeq[4];int dataOrder;int origin;int align;int width;int height;struct _IplROI* roi;struct _IplImage* maskROI;void* imageId;struct _IplTileInfo* tileInfo;int imageSize;char* imageData;int widthStep;int BorderMode[4];int BorderConst[4];char* imageDataOrigin;
} IplImage;
#include <stdio.h>#include <cv.h>#include <highgui.h>
void saturate_sv( IplImage* img ){ for( int y=0; y<img->height; y++ ) { uchar* ptr = (uchar*) ( img->imageData + y * img->widthStep ); for( int x=0; x<img->width; x++ ) { ptr[3*x+1] = 255; ptr[3*x+2] = 255; } }}
int main( int argc, char** argv ){ IplImage* img = cvLoadImage( argv[1] ); cvNamedWindow("Example1", CV_WINDOW_AUTOSIZE ); saturate_sv(img); cvShowImage("Example1", img ); cvWaitKey(0); cvReleaseImage( &img ); cvDestroyWindow("Example1");}
#include <stdio.h>#include <cv.h>#include <highgui.h>
void saturate_sv( IplImage* img ){ for( int y=0; y<img->height; y++ ) { uchar* ptr = (uchar*) ( img->imageData + y * img->widthStep ); for( int x=0; x<img->width; x++ ) { ptr[3*x+1] = 255; ptr[3*x+2] = 255; } }}
int main( int argc, char** argv ){ IplImage* img = cvLoadImage( argv[1] ); cvNamedWindow("Example1", CV_WINDOW_AUTOSIZE ); saturate_sv(img); cvShowImage("Example1", img ); cvWaitKey(0); cvReleaseImage( &img ); cvDestroyWindow("Example1");}
ROI
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
cvSetImageROI
ROI
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
cvSetImageROI
cvAddS
ROI
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
cvSetImageROI
cvAddS
#include <cv.h>#include <highgui.h>// ch3_ex3_12 image_name x y width height add# int main(int argc, char** argv){ IplImage* src; cvNamedWindow("Example3_12_pre", CV_WINDOW_AUTOSIZE); cvNamedWindow("Example3_12_post", CV_WINDOW_AUTOSIZE); if( argc == 7 && ((src=cvLoadImage(argv[1],1)) != 0 )) {
int x = atoi(argv[2]);int y = atoi(argv[3]);int width = atoi(argv[4]);int height = atoi(argv[5]);int add = atoi(argv[6]);cvShowImage( "Example3_12_pre", src);cvSetImageROI(src, cvRect(x,y,width,height));cvAddS(src, cvScalar(add, add, add),src);cvResetImageROI(src);cvShowImage( "Example3_12_post",src);cvWaitKey();
} cvReleaseImage( &src ); cvDestroyWindow("Example3_12_pre"); cvDestroyWindow("Example3_12_post"); return 0;}
#include <cv.h>#include <highgui.h>// ch3_ex3_12 image_name x y width height add# int main(int argc, char** argv){ IplImage* src; cvNamedWindow("Example3_12_pre", CV_WINDOW_AUTOSIZE); cvNamedWindow("Example3_12_post", CV_WINDOW_AUTOSIZE); if( argc == 7 && ((src=cvLoadImage(argv[1],1)) != 0 )) {
int x = atoi(argv[2]);int y = atoi(argv[3]);int width = atoi(argv[4]);int height = atoi(argv[5]);int add = atoi(argv[6]);cvShowImage( "Example3_12_pre", src);cvSetImageROI(src, cvRect(x,y,width,height));cvAddS(src, cvScalar(add, add, add),src);cvResetImageROI(src);cvShowImage( "Example3_12_post",src);cvWaitKey();
} cvReleaseImage( &src ); cvDestroyWindow("Example3_12_pre"); cvDestroyWindow("Example3_12_post"); return 0;}
ROI by widthStep
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
NULL
ROI by widthStep
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
NULLNULL
ROI by widthStep
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
NULL
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
cvAddS
NULL
ROI by widthStep
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
void cvSetImageROI( IplImage* image, CvRect rect );
void cvResetImageROI( IplImage* image );
NULL
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
typedef struct _IplImage {........................int width;int height;........................struct _IplROI* roi;
........................ char* imageData;
int widthStep; ........................} IplImage;
cvAddS
int main(int argc, char** argv){ IplImage* interest_img; CvRect interest_rect; if( argc == 7 && ((interest_img=cvLoadImage(argv[1])) != 0 )) { interest_rect.x = atoi(argv[2]); interest_rect.y = atoi(argv[3]); interest_rect.width = atoi(argv[4]); interest_rect.height = atoi(argv[5]); int add = atoi(argv[6]);
IplImage *sub_img = cvCreateImageHeader( cvSize(interest_rect.width, interest_rect.height), interest_img->depth, interest_img->nChannels ); sub_img->origin = interest_img->origin; sub_img->widthStep = interest_img->widthStep; sub_img->imageData = interest_img->imageData + interest_rect.y * interest_img->widthStep + interest_rect.x * interest_img->nChannels; cvAddS( sub_img, cvScalar(add, add, add), sub_img ); cvReleaseImageHeader(&sub_img);
cvNamedWindow( "Roi_Add", CV_WINDOW_AUTOSIZE ); cvShowImage( "Roi_Add", interest_img ); cvWaitKey(); } return 0;}
int main(int argc, char** argv){ IplImage* interest_img; CvRect interest_rect; if( argc == 7 && ((interest_img=cvLoadImage(argv[1])) != 0 )) { interest_rect.x = atoi(argv[2]); interest_rect.y = atoi(argv[3]); interest_rect.width = atoi(argv[4]); interest_rect.height = atoi(argv[5]); int add = atoi(argv[6]);
IplImage *sub_img = cvCreateImageHeader( cvSize(interest_rect.width, interest_rect.height), interest_img->depth, interest_img->nChannels ); sub_img->origin = interest_img->origin; sub_img->widthStep = interest_img->widthStep; sub_img->imageData = interest_img->imageData + interest_rect.y * interest_img->widthStep + interest_rect.x * interest_img->nChannels; cvAddS( sub_img, cvScalar(add, add, add), sub_img ); cvReleaseImageHeader(&sub_img);
cvNamedWindow( "Roi_Add", CV_WINDOW_AUTOSIZE ); cvShowImage( "Roi_Add", interest_img ); cvWaitKey(); } return 0;}
Getting to Know OpenCV
Matrix and Image Operators
ArrayMatrixImage
Even though OpenCV is implemented in C, the structures used in OpenCV have an object-oriented design; in effect, IplImage is derived from CvMat, which is derived from CvArr
Array Operators
Web
Table
cvCalcCovarMatrix
void cvCalcCovarMatrix (const CvArr** vects,int count,CvArr* cov_mat,CvArr* avg,int flags
);
void cvCalcCovarMatrix (const CvArr** vects,int count,CvArr* cov_mat,CvArr* avg,int flags
);
Detail
Example
Getting to Know OpenCV
Drawing Things
Drawing Functions
Drawing functions work with matrices/images of arbitrary depth
The boundaries of the shapes can be rendered with antialiasing– implemented only for 8-bit images for now
All the functions include the parameter color that uses a rgb value (that may be constructed with CV_RGB macro or the cvScalar function ) for color images and brightness for grayscale images
Drawing Functions
Clipping– If a drawn figure is partially or completely outside
the image, the drawing functions clip it. sub-pixel accuracy
– many drawing functions can handle pixel coordinates specified with sub-pixel accuracy, i.e., the coordinates can be passed as fixed-point numbers, encoded as integers.
– The number of fractional bits is specified by the shift parameter and the real point coordinates are calculated as
Point( , ) Point2f ( 2 , 2 )shift shiftx y x y
CV_RGB
Constructs a color value
#define CV_RGB( r, g, b ) cvScalar( (b), (g), (r) )
Line
void cvLine( CvArr* img, CvPoint pt1, CvPoint pt2, CvScalar color, int thickness=1, int line_type=8, int shift=0 );
void cvLine( CvArr* img, CvPoint pt1, CvPoint pt2, CvScalar color, int thickness=1, int line_type=8, int shift=0 );
line_type Type of the line:8 (or 0) - 8-connected line.4 - 4-connected line.CV_AA - antialiased line.
Draws a line by the Bresenham’s algorithm
Rectangle
void cvRectangle( CvArr* img, CvPoint pt1, CvPoint pt2, double color, int thickness=1 int line_type=8, int shift=0 );
void cvRectangle( CvArr* img, CvPoint pt1, CvPoint pt2, double color, int thickness=1 int line_type=8, int shift=0 );
Draws simple, thick or filled rectangle
thickness Thickness of lines that make up the rectangle.Negative values, e.g., CV_FILLED, make the function to draw a filled rectangle.
Circle
void cvCircle( CvArr* img, CvPoint center, int radius, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
void cvCircle( CvArr* img, CvPoint center, int radius, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
Draws simple, thick or filled circle
Ellipsevoid cvEllipse( CvArr* img, CvPoint center, CvSize axes, double angle, double start_angle, double end_angle, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
void cvEllipse( CvArr* img, CvPoint center, CvSize axes, double angle, double start_angle, double end_angle, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
Draws simple or thick elliptic arc or fills ellipse sector
EllipseBox
void cvEllipseBox( CvArr* img, CvBox2D box, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
void cvEllipseBox( CvArr* img, CvBox2D box, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
An alternate way to draw ellipse
typedef struct { CvPoint2D32f center; CvSize2D32f size; float angle;} CvBox2D;
typedef struct { CvPoint2D32f center; CvSize2D32f size; float angle;} CvBox2D;
FillPoly
void cvFillPoly( CvArr* img, CvPoint** pts, int* npts, int contours, cvScalar color, int line_type=8, int shift=0 );
void cvFillPoly( CvArr* img, CvPoint** pts, int* npts, int contours, cvScalar color, int line_type=8, int shift=0 );
Fills polygons interior
pts Array of pointers to polygons. npts Array of polygon vertex counters. contours #contours that bind the filled region.
pts Array of pointers to polygons. npts Array of polygon vertex counters. contours #contours that bind the filled region.
FillConvexPoly
void cvFillConvexPoly( CvArr* img, CvPoint* pts, int npts, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
void cvFillConvexPoly( CvArr* img, CvPoint* pts, int npts, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
Fills convex polygon
pts Array of pointers to a single polygon
npts Polygon vertex counter
pts Array of pointers to a single polygon
npts Polygon vertex counter
PolyLine
void cvPolyLine( CvArr* img, CvPoint** pts, int* npts, int contours, int is_closed, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
void cvPolyLine( CvArr* img, CvPoint** pts, int* npts, int contours, int is_closed, cvScalar color, int thickness=1 int line_type=8, int shift=0 );
Draws simple or thick polygons
pts Array of pointers to polygons. npts Array of polygon vertex counters. contours #contours that bind the filled region.is_closed Indicates whether the polylines must be drawn closed.
pts Array of pointers to polygons. npts Array of polygon vertex counters. contours #contours that bind the filled region.is_closed Indicates whether the polylines must be drawn closed.
Getting to Know OpenCV
Drawing Text
InitFont
void cvInitFont( CvFont* font, int font_face, double hscale, double vscale, double shear=0, int thickness=1, int line_type=8 );
void cvInitFont( CvFont* font, int font_face, double hscale, double vscale, double shear=0, int thickness=1, int line_type=8 );
Initializes font structure
InitFont
void cvInitFont( CvFont* font, int font_face, double hscale, double vscale, double shear=0, int thickness=1, int line_type=8 );
void cvInitFont( CvFont* font, int font_face, double hscale, double vscale, double shear=0, int thickness=1, int line_type=8 );
Initializes font structure
InitFont
void cvInitFont( CvFont* font, int font_face, double hscale, double vscale, double shear=0, int thickness=1, int line_type=8 );
void cvInitFont( CvFont* font, int font_face, double hscale, double vscale, double shear=0, int thickness=1, int line_type=8 );
Initializes font structure
PutText
void cvPutText( CvArr* img, const char* text, CvPoint org, const CvFont* font, CvScalar color );
void cvPutText( CvArr* img, const char* text, CvPoint org, const CvFont* font, CvScalar color );
Draws text string
GetTextSize
void cvGetTextSize( const char* text_string, const CvFont* font, CvSize* text_size, int* baseline );
void cvGetTextSize( const char* text_string, const CvFont* font, CvSize* text_size, int* baseline );
Retrieves width and height of text string
Getting to Know OpenCV
Data Persistence
Reading and Writing Images and Video
Topics on HighGUI
A Simple Way to Save and Load OpenCV Matrices
CvMat A = cvMat( 5, 5, CV_32F, the_matrix_data );
cvSave( “my_matrix.xml”, &A );
. . .
// to load it then in some other program use …
CvMat* A1 = (CvMat*) cvLoad( “my_matrix.xml” );
CvMat A = cvMat( 5, 5, CV_32F, the_matrix_data );
cvSave( “my_matrix.xml”, &A );
. . .
// to load it then in some other program use …
CvMat* A1 = (CvMat*) cvLoad( “my_matrix.xml” );
The structure CvFileStorage is a “black box” representation of the file storage associated with a file on disk.
On disk, the data is stored in an XML or YAML format.
File Storage
typedef struct CvFileStorage{ ... // hidden fields} CvFileStorage
typedef struct CvFileStorage{ ... // hidden fields} CvFileStorage
XML & YAMLXML:
<?xml version="1.0">
<opencv_storage>
<A type_id="opencv-matrix">
<rows>3</rows>
<cols>3</cols>
<dt>f</dt>
<data>1. 0. 0. 0. 1. 0. 0. 0. 1.</data>
</A>
</opencv_storage>
XML:
<?xml version="1.0">
<opencv_storage>
<A type_id="opencv-matrix">
<rows>3</rows>
<cols>3</cols>
<dt>f</dt>
<data>1. 0. 0. 0. 1. 0. 0. 0. 1.</data>
</A>
</opencv_storage>
YAML:%YAML:1.0A: !!opencv-matrix rows: 3 cols: 3 dt: f data: [ 1., 0., 0., 0., 1., 0., 0., 0., 1.]
YAML:%YAML:1.0A: !!opencv-matrix rows: 3 cols: 3 dt: f data: [ 1., 0., 0., 0., 1., 0., 0., 0., 1.]
XML uses nested tags
YAML uses indentation
An example of 3×3 floating-point identity matrix A
Open & Release
CvFileStorage* cvOpenFileStorage( const char* filename, CvMemStorage* memstorage, int flags );
CvFileStorage* cvOpenFileStorage( const char* filename, CvMemStorage* memstorage, int flags );
void cvReleaseFileStorage( CvFileStorage** fs );
void cvReleaseFileStorage( CvFileStorage** fs );
flags – Can be one of the following:CV_STORAGE_READ - the storage is open for reading CV_STORAGE_WRITE - the storage is open for writing
Writing
Reading
Example: Writing & Reading XML
<?xml version=“1.0”?>
<opencv_storage>
<frame_count>10</frame_count>
<frame_size>320 200</frame_size>
<color_cvt_matrix type_id=“opencv-matrix”>
<rows>3</rows> <cols>3</cols>
<dt>f</dt>
<data>…</data></color_cvt_matrix>
</opencv_storage>
XML version of cfg.xml on disk
Example: Writing & Reading XML
<?xml version=“1.0”?>
<opencv_storage>
<frame_count>10</frame_count>
<frame_size>320 200</frame_size>
<color_cvt_matrix type_id=“opencv-matrix”>
<rows>5</rows> <cols>5</cols>
<dt>f</dt>
<data>…</data></color_cvt_matrix>
</opencv_storage>
<?xml version=“1.0”?>
<opencv_storage>
<frame_count>10</frame_count>
<frame_size>320 200</frame_size>
<color_cvt_matrix type_id=“opencv-matrix”>
<rows>5</rows> <cols>5</cols>
<dt>f</dt>
<data>…</data></color_cvt_matrix>
</opencv_storage>
XML version of cfg.xml on disk
Example: Writing & Reading XML
XML version of cfg.xml on disk<?xml version=“1.0”?><opencv_storage><frame_count>10</frame_count><frame_size>320 200</frame_size><color_cvt_matrix type_id=“opencv-matrix”><rows>5</rows> <cols>5</cols><dt>f</dt><data>…</data></color_cvt_matrix></opencv_storage>
<?xml version=“1.0”?><opencv_storage><frame_count>10</frame_count><frame_size>320 200</frame_size><color_cvt_matrix type_id=“opencv-matrix”><rows>5</rows> <cols>5</cols><dt>f</dt><data>…</data></color_cvt_matrix></opencv_storage>
#include <cv.h>#include <highgui.h>#include <stdio.h>
int main(int argc, char** argv){ printf("Example 3_19 Reading in cfg.xml\n"); CvFileStorage* fs = cvOpenFileStorage( "cfg.xml", 0, CV_STORAGE_READ );
int frame_count = cvReadIntByName(fs, 0, "frame_count", 5 /* default value */);
CvSeq* s = cvGetFileNodeByName(fs,0,"frame_size")->data.seq; int frame_width = cvReadInt((CvFileNode*) cvGetSeqElem(s,0)); int frame_height = cvReadInt((CvFileNode*) cvGetSeqElem(s,1));
CvMat* color_cvt_matrix = (CvMat*) cvRead(fs, 0); printf("frame_count=%d, frame_width=%d, frame_height=%d\n", frame_count,frame_width,frame_height);
cvReleaseFileStorage( &fs );}
#include <cv.h>#include <highgui.h>#include <stdio.h>
int main(int argc, char** argv){ printf("Example 3_19 Reading in cfg.xml\n"); CvFileStorage* fs = cvOpenFileStorage( "cfg.xml", 0, CV_STORAGE_READ );
int frame_count = cvReadIntByName(fs, 0, "frame_count", 5 /* default value */);
CvSeq* s = cvGetFileNodeByName(fs,0,"frame_size")->data.seq; int frame_width = cvReadInt((CvFileNode*) cvGetSeqElem(s,0)); int frame_height = cvReadInt((CvFileNode*) cvGetSeqElem(s,1));
CvMat* color_cvt_matrix = (CvMat*) cvRead(fs, 0); printf("frame_count=%d, frame_width=%d, frame_height=%d\n", frame_count,frame_width,frame_height);
cvReleaseFileStorage( &fs );}
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