what is the best format and resolution for digital art on facebook?

[harpo]

i've started adding some of my art onto facebook but it keeps turning out really grainy and bad quality

i've tried saving in jpeg and png, from different programs but it always turns out the same
i can't find any high-quality check boxes?
okay yeah found the check box but it's not changing anything
:c
yeah i use tumblr haha
just wanted to show my friends
bit of a let down
haha the picture is actually perfect quality, daniel, mate i've looked at it through four different image viewers, not grainy or bad quality at all