In EXIF, whether applied to JPEG or TIFF, the header comes first, then the thumbnail if present, then the primary image. Exactly as you'd want (which is more th

In EXIF, whether applied to JPEG or TIFF, the header comes first, then the thumbnail if present, then the primary image. Exactly as you'd want (which is more than can be said for much of EXIF, e.g. that it lacks time zone encodings).