x264 --tune

[x265]

Should i use --tune grain or film for this grainy BD?

Source - Taxi Driver (Mastered in 4k)

Screenshots :

http://imgur.com/8bP9fre

http://i.imgur.com/sJR1Q97.jpg

[kalehrl]

If you specifically want to keep the grain, use --tune grain.

[nhakobian]

Not only that, you will also have to make sure the bitrate is high enough (or the crf is low enough) to retain the grain that you want.