c[t_]:=RGBColor[Sin[Pi t],Sin[Pi t],1-Sin[Pi t]];
J=Compile[{x,y,u,v}, Module[{z=u+I v,k=0},While[Abs[z]<200.&&k<50,z=z^2+x+I y;++k];k]];
Julia[x_,y_]:=DensityPlot[50-J[x,y,u,v],{u,-1.3,1.3},{v,-1.3,1.3},
  ColorFunction->c,Frame->False,Axes->False,PlotPoints->1200,Mesh->False];
Julia[0.455,0]

