Sepia effect

[MrsCalahan]

Hi,

I try to set an Sepia effect on a picture.
It works via console: convert -sepia-tone 80% bild.jpg bild.jpg

but I need it in this style:
my $var_img= Image::Magick->new();
my $error=$var_img->Read("$var_datei");
$var_img->OilPaint(radius=>"$var_p1")

Can anybody help me?