Hi guys - after my several issues I managed to solve them by my self, but now I have only cosmetic problem with my custom maps. As you can see on screen below Heightmap is almost perfectly smoothed.
But in the end in game map looks like this:
I'm guessing it has something with image depth.
Output RAW from L3DT is 16 BIT, but Metin2 map convertert by BlackYuko decreases RAW depth to 8Bit causing such rough ground.
I would be much satisfied if somenone could help me to navigate me to right way in map making.