mediasubtitler subtitle problem

[diogenesis]

hi,
I hope sb can help me with this problem. Actually this is not about media subtitler. the problem is about the subtitler filter of virtualdub. when I complete the conversion the subtitles look so blurred like this:


There is an option on the subtitler filter configuration that makes it a little better but I'd like to know how to get rid of the problem.

Thanks for any help.