/* Example showing how to call a couple of vips functions using an input
 * image file and creating an output file
 * also gathers some info on the input image
 */
#include <stdio.h>
#include <vips/vips.h>

int
main( int argc, char **argv )
{
  VipsImage *in;
  double mean;
  VipsImage *out;

  if( VIPS_INIT( argv[0] ) )
    vips_error_exit( NULL ); 

  if( argc != 3 )
    vips_error_exit( "usage: %s infile outfile", argv[0] ); 
  
  if( !(in = vips_image_new_from_file( argv[1], NULL )) )
    vips_error_exit( NULL );

  printf( "image width = %d\n", vips_image_get_width( in ) ); 

  if( vips_avg( in, &mean, NULL ) )
    vips_error_exit( NULL );

  printf( "mean pixel value = %g\n", mean ); 

  /* generate photo nexative - replace with other vips_ funcs */
  if( vips_invert( in, &out, NULL ) )
    vips_error_exit( NULL );

  g_object_unref( in ); 

  if( vips_image_write_to_file( out, argv[2], NULL ) )
    vips_error_exit( NULL );

  g_object_unref( out ); 

  return( 0 );
}