【明報專訊】For those of us living in the city, we have grown accustomed to be surrounded by "smart screens". From the large outdoor digital screens of moving images (such as those seen on the tall International Commerce Centre building), the indoor digital advertising billboards in shopping malls, to our personal digital devices, modern life has been transformed by a new, interesting kind of realisation. We now realise that walls are not merely plain surfaces. Instead, they can be used as decoration, public announcement, advertisement, and even digital art.