Open CV Tutorial - Basic operations for images Rotate and Scale

In this tutorials of OpenCV we will do some basic but interesting operartion on images. We rotate the image and scale it down.

For this we will use a matrix and rotate it. 

/************************************************/

#include "cv.h"

#include "highgui.h"

#include "math.h"

int main()

{

IplImage* src;

IplImage* dst;

int delta;

int angle;

src = cvLoadImage("apple.bmp", 1);

dst = cvCloneImage( src );

delta = 1; angle = 0;

cvNamedWindow( "src", 1 );

cvShowImage( "src", src );

for(;;)

{

float m[6];

double factor = (cos(angle*CV_PI/180.) + 1.1)*3;

CvMat M = cvMat( 2, 3, CV_32F, m );

int w = src->width;

int h = src->height;

m[0] = (float)(factor*cos(-angle*2*CV_PI/180.));

m[1] = (float)(factor*sin(-angle*2*CV_PI/180.));

m[2] = w*0.5f;

m[3] = -m[1];

m[4] = m[0];

m[5] = h*0.5f;

cvGetQuadrangleSubPix( src, dst, &M, 1, cvScalarAll(0));

cvNamedWindow( "dst", 1 ); cvShowImage( "dst", dst );

if( cvWaitKey(5) == 27 )

break;

angle = (angle + delta) % 360;

}

return 0;

}

OUTPUT:- 

ALSO READ :- 

• Open CV Tutorial and Introduction
• Linking OpenCV library in DEVC++
• OPENCV Tutorial - Basic operations for images Dilate/Erode

• Open CV Tutorial - Basic operations for images ' Canny edge detection'