  Control over plasmonic colors on the nanoscale is of great interest for
high-resolution display, imaging, and information encryption applications.
However, so far, very limited schemes have been attempted for dynamic plasmonic
color generation. In this paper, we demonstrate a scanning plasmonic color
generation scheme, in which subwavelength plasmonic pixels can be laterally
switched on/off through directional hydrogenation/dehydrogenation of a
magnesium screen. We show several dynamic plasmonic color displays with
different scanning functions by varying the number and geometries of the
palladium gates, where hydrogen enters the scanning screens. In particular, we
employ the scanning effects to create a dynamic plasmonic quick response code.
The information cannot be decrypted by varying the polarization states of light
or by accessing the physical features. Rather, it can only be read out using
hydrogen as a decoding key. Our work advances the established design concepts
for plasmonic color printing and provides insights into the development of
optical information storage and anticounterfeiting features.
