I've made progress - I now have it building using the C api...

I'm puzzled by this, however.

This code works:

libraw_data_t * image = libraw_init(0);
libraw_open_file(image, "IMG_0174.cr2");
libraw_unpack_thumb(image);
libraw_dcraw_thumb_writer(image, "h:\\outcr2.jpg");

The return codes from all function calls is zero, and the output file is created ok.

Yet, when I examine the image->thumbnail properties, everything is zero and the thumbnail type is LIBRAW_THUMBNAIL_UNKNOWN

I'd like to be able to process the thumbnail data without wasting time writing to disk, but it doesn't seem to be there. Yet it writes to disk ok.

Is there some other step I need to take to get to the thumbnail/preview data?

Many thanks