Example of how to use VipsOperation after filling a VipsImage from local buffer ( vips_image_new_from_memory() )

[skf-git]

I am trying to define a function so that I can apply a VipsOperation to a local an image buffer of Gray format (YY extracted from YUYV), so my buffer contains image pixels, one byte each pixel, with width=VRES and height=HRES.

I basically wanted to extract the difference of angles of main lines that the operation stores in (Xsize).

I didn't define VipsOperation before as I thought of calling vips_hough_line function with only VipsImages declared and initialised as in the code.

But the operation was failing (sends -1 instead of 0) when I don't set the optional argument (width and height) and it reports the error I followed below when I do set them as in the code.

I kept some different lines I tried commented in case whoever sees the issue trues to reproduce it or try what I tried. But these are poor guesses without proper knowledge of how this actually works (GObject and more specifically here "g_param_spec_pool_lookup " as shown in gdb backtrace).

void vips_image_process(unsigned char * vips_buffer, unsigned char * prev_vips_buffer){


	printf("\ndone 0\n");
	/*if( VIPS_INIT(NULL) ){
		vips_error_exit( NULL );
	}*/
	VipsImage *image_curr;
	VipsImage *image_prev;
	VipsOperation *op;
	op = vips_operation_new( "hough_line" );

	printf("\ndone 1\n");
	image_curr = vips_image_new_from_memory(vips_buffer, (size_t)((unsigned)(PIXEL_SIZE*VRES*HRES)), VRES, HRES, BYTES_PER_PIXEL,VIPS_FORMAT_UCHAR);
	//image_curr = vips_image_new_from_memory(vips_buffer, (size_t)((unsigned)(PIXEL_SIZE*VRES*HRES)), PIXEL_SIZE*VRES, PIXEL_SIZE*HRES, BYTES_PER_PIXEL,VIPS_FORMAT_UCHAR);

	//image_curr = vips_image_new_from_buffer(vips_buffer, PIXEL_SIZE*VRES*HRES,(char*)NULL, NULL);
	//image_curr = vips_image_matrix_from_array(width, height, *array, size);
	printf("done 2\n");

	image_prev = vips_image_new_from_memory(prev_vips_buffer, (size_t)((unsigned)(PIXEL_SIZE*VRES*HRES)), VRES, HRES, BYTES_PER_PIXEL,VIPS_FORMAT_UCHAR);

	//image_prev = vips_image_new_from_memory(prev_vips_buffer, (size_t)((unsigned)(PIXEL_SIZE*VRES*HRES)), PIXEL_SIZE*VRES, PIXEL_SIZE*HRES, BYTES_PER_PIXEL,VIPS_FORMAT_UCHAR);
	//image_prev = vips_image_new_from_buffer(vips_buffer, PIXEL_SIZE*VRES*HRES, (char*)NULL, NULL);
	//image_prev = vips_image_matrix_from_array(width, height, *array, size);


	printf("done 3\n");
	VipsImage *im_hough_curr = vips_image_new();
	VipsImage *im_hough_prev = vips_image_new();
	printf("done 4\n");

	//vips_check_init();

	if( vips_hough_line( image_curr, &im_hough_curr, VRES, HRES, NULL)==0 ){
		printf("first hough compute done");
	}
	if( vips_hough_line(image_prev, &im_hough_prev, VRES, HRES, NULL)==0 ){
		printf("Angle difference : %d", abs( im_hough_curr->Xsize - im_hough_prev->Xsize) );
	}
	else{
		printf("Vips Hough Computation Error. ");
	}

	//vips_image_finalize( (GObject*)image_curr );
	//vips_image_finalize( (GObject*)image_prev );
	//vips_image_finalize( (GObject*)im_hough_curr );
	//vips_image_finalize( (GObject*)im_hough_prev );

	//vips_shutdown();

	g_object_unref( im_hough_curr );
	g_object_unref( im_hough_prev );
	g_object_unref( image_prev );
	g_object_unref( image_curr );


}

I get this error that I spent a lot of time now trying to see how to correct it.

Undefined command: "". Try "help".
(gdb) #0 0x00007ffff6f48ef8 in __strchr_avx2 () at ../sysdeps/x86_64/multiarch/strchr-avx2.S:57
(gdb) #1 0x00007ffff73e74df in g_param_spec_pool_lookup () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
(gdb) #2 0x00007ffff73e1331 in g_object_class_find_property () at /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0
(gdb) #3 0x00007ffff7757858 in vips_object_get_argument () at /usr/lib/x86_64-linux-gnu/libvips.so.42
(gdb) #4 0x00007ffff7758ae9 in vips_object_set_valist () at /usr/lib/x86_64-linux-gnu/libvips.so.42
(gdb) #5 0x00007ffff77682dd in vips_call_required_optional () at /usr/lib/x86_64-linux-gnu/libvips.so.42
(gdb) #6 0x00007ffff7768c56 in () at /usr/lib/x86_64-linux-gnu/libvips.so.42
(gdb) #7 0x00007ffff77690f9 in vips_call_split () at /usr/lib/x86_64-linux-gnu/libvips.so.42
(gdb) #8 0x00007ffff7689736 in vips_hough_line () at /usr/lib/x86_64-linux-gnu/libvips.so.42
(gdb) #9 0x0000555555556018 in vips_image_process (vips_buffer=0x55555591b3a0 <scratchpad_buffer> "DCEFLJHIJHGHIIIIIKKJIIHHHHIKKKIHHIHHIIHJIIGGHHHGFHGGHHHIHHHGHHHJIJKLNMMONNNMMNOONNNMKIJJIIIIHIJIHGHIJJKKLMMNOOONONNNNNNNOPOOOPPOQOPPQQOPOPPOOPQPOOQQQQQQQQPQQPONOOOOOPPRRSRRQQQPOPRRRSSTTRTSQOPOUURSSQOO"..., prev_vips_buffer=0x555556789020 <last_frame> "DCEFLJHIJHGHIIIIIKKJIIHHHHIKKKIHHIHHIIHJIIGGHHHGFHGGHHHIHHHGHHHJIJKLNMMONNNMMNOONNNMKIJJIIIIHIJIHGHIJJKKLMMNOOONONNNNNNNOPOOOPPOQOPPQQOPOPPOOPQPOOQQQQQQQQPQQPONOOOOOPPRRSRRQQQPOPRRRSSTTRTSQOPOUURSSQOO"...) at capturelib.c:789
(gdb) #10 0x0000555555555ba2 in process_image (p=0x555555759230 <ring_buffer+16>, size=614400) at capturelib.c:546
(gdb) #11 0x000055555555649c in mainloop () at capturelib.c:932
(gdb) #12 0x0000555555556eef in v4l2_frame_acquisition_loop (dev_name=0x555555557754 "/dev/video0") at capturelib.c:1269
(gdb) #13 0x0000555555555174 in main (argc=1, argv=0x7fffffffdea8) at capture.c:27

Thank you in advance.

[jcupitt]

Hi @skf-git,

Sorry, I don't really understand the problem. Do you just want to run hough_line twice?

Could you post a complete program I can compile and test?