It is possible to do

import plopp as pp

da = pp.data.data1d(masks=True)
da.plot(vmax=1.0, mask_color='red')

and

import plopp as pp

da = pp.data.data2d(masks=True)
da.plot(vmax=1.0, mask_cmap='red')

but this is missing from the docs.

Also, maybe there should be two arguments for 2d images, mask_cmap and mask_color, instead of using mask_cmap for both cases, as it's rather confusing.