Question

I am trying to use opencv2, built on ubuntu 10.04 to get a simple program going which reads a exisitng image, creates another image from it and resize that original image by 2(both width and height). Below is the code. Upon execution, I don’t see the resized image window.

# include "stdio.h"
#include "opencv2/highgui/highgui_c.h"
#include <opencv2/imgproc/types_c.h>

int main( int argc, char** argv ) {
  IplImage* img = 0;
  IplImage* dst_img = 0;


  if( argc < 2 ) {
    printf( "Usage: Accepts one image as argument\n" );
    exit( EXIT_SUCCESS );
  }

  img = cvLoadImage( argv[1],1);
  if( !img ) {
    printf( "Error loading image file %s\n", argv[1]);
    exit( EXIT_SUCCESS );
  }

  dst_img = cvCreateImage(cvSize(img->width*2,img->height*2),img->depth,img->nChannels);
  if( !dst_img ) {
    printf( "Error loading output image file \n");
    exit( EXIT_SUCCESS );
  }


  cvResize(img,dst_img,CV_INTER_LINEAR); 

  cvNamedWindow( "Original Image", CV_WINDOW_AUTOSIZE );
  cvNamedWindow( "RescaledImage", CV_WINDOW_AUTOSIZE );

  cvMoveWindow( "Original Image", 720, 515 );
  cvMoveWindow( "RescaledImage", 1500,1200 );

  cvShowImage( "Original Image", img );
  cvShowImage( "RescaledImage", dst_img );

  cvWaitKey( 0 );

  cvReleaseImage( &img );
  cvReleaseImage( &dst_img );

  cvDestroyWindow( "Original Image" );
  cvDestroyWindow( "RescaledImage" );

  return EXIT_SUCCESS;
  }

I am using cvCreateImage(), & cvResize() correctly above?

How can I resize the input image by 2 in both directions?

Any pointers on web(blogs,tutorials) , books for OpenCV which has lot of sample code which one can use to study opencv hands-on?

Answer 1

cvMoveWindow( "RescaledImage", 1500,1200 ); 

My mistake. I thought this was the dimension of window/image. But this is the position of the window on screen. changed it to –

cvMoveWindow( "RescaledImage", 100,100 );

Both windows are fine now!