Dear Bogdan!
I,ve just observed on your question, where you work with orientation tag of JPEG. I look through my JPEGs and I see, that ALL of them have tag 'horizontal' - even images, which are vertical in fact. I do not know what this tag means in JPEG, and whether such programs as DPP, AcDsee, FastStone etc use this tag while they produce images, but it is fact that in all my JPEGs this tag is the same.
Igor