Best way to add watermark?

Hi,

What would be the best way to add a watermark in holoviews?

My approach:

Code:

x = xr.DataArray(b.data,dims=("CVD","date","color"),
                     coords={"CVD":np.linspace(0,1,200),
                             "date":np.asarray(np.linspace(pd.Timestamp("2020-08-01").value,
                                                pd.Timestamp("2020-08-02").value,602),
                                               dtype='datetime64[ns]'),
                             "color":np.linspace(0,4,4)})
b = hv.RGB(x,kdims=["date","CVD"]).opts(alpha=0.3)

It’s not ideal, as everything gets distorted in a non-fixed size chart.
Also, I’m not sure why the diagonal lines appear so jagged. Any ideas?