sum a lot of images in constant memory

try236.c

/* compile with
 * 	gcc -g -Wall try236.c `pkg-config vips --cflags --libs`
 */

#include <stdio.h>
#include <stdlib.h>

#include <vips/vips.h>

int
main( int argc, char **argv )
{
	VipsImage *accumulator;
	int i;

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

	vips_cache_set_max( 0 ); 
	vips_leak_set( TRUE ); 

	accumulator = NULL;
	for( i = 2; i < argc; i++) {
		VipsImage *im;
		VipsImage *memory;

		printf( "image %d ...\r", i - 1 );
		fflush( stdout ); 

		im = vips_image_new_from_file( argv[i], 
			"access", VIPS_ACCESS_SEQUENTIAL, 
			NULL ); 

		if( accumulator ) {
			VipsImage *sum;

			if( vips_add( im, accumulator, &sum, NULL ) )
				vips_error_exit( NULL ); 
			g_object_unref( im );
			im = sum;
		} 

		memory = vips_image_new_memory();
		if( vips_image_write( im, memory ) ) 
			vips_error_exit( NULL ); 
		g_object_unref( im ); 

		if( accumulator )
			g_object_unref( accumulator ); 
		accumulator = memory;
	}

	if( vips_image_write_to_file( accumulator, argv[1], NULL ) )
		vips_error_exit( NULL ); 
	g_object_unref( accumulator ); 

	printf( "\n" ); 

	return( 0 );
}