As a general remark first: Use the pngcairo
terminal which provides much better antialiasing.
For processing of your data you can use different smoothing options, like smooth csplines
, smooth bezier
or similar (see e.g. help smooth
in the interactive gnuplot terminal):
plot "1" using 1:2 smooth csplines, "2" using 1:2 smooth csplines
Which smoothing variant you use depend again on the meaning of your data.
What could also help, is to use other point types then the default ones, e.g. pt 1
for the first and pt 7
for the second one, see Gnuplot line types for the use of the test
command to check the available point types.