LTNOspline = Interpolation[DiscreateLT, Method -> "Hermite"]

DiscreateLT =
  Flatten[Table[{{sx, sy}, Int[sx, sy]}, {sx, sxmin, sxmax,
     sxInc}, {sy, symin, symax, syInc}], 1];

Int[sx_, sy_] :=
  NIntegrate[I1spline[x] Exp[- (sx + I sy) x], {x, 0, xmaxLP}];

LTNOspline = Interpolation[DiscreateLT, Method -> "Hermite"]

LTNOspline = Interpolation[DiscreateLT, Method -> "Spline"]