1) Download the version you want from https://drive.google.com/open?id=1v_l0i ... PIUjxUMP2f
2) Unzip the zip folder in your terrain folder (<factorio-path>/data/base/graphics/terrain/)
If there is demand I may try to improve them further, but for now you can use this one. Since it is not a mod, it should not interfere with achievements.
I hereby publish these textures under the public domain. You may use and distribute them as you want, with no restrictions whatsoever.