While there were signs on Monday that Hong Kong's protests might be coming to a low ebb, their visual impact looks likely to last for a while.

"This is the most well-designed protest in recent memory," says Colette Gaiter, an Associate Professor of Art at the University of Delaware who has done extensive research on protest art.

"Unlike the U.S. Occupy movement three years ago -- which featured rough hand lettered signs on torn cardboard representing the grass-roots nature of the protests and economic status of the protesters -- the Hong Kong protests have attracted professional designers," Gaiter explains. "There is an elevated aesthetic sensibility even in the ubiquitous handwritten signs and Post-it notes."

Art can be seen all over the protests. Outside Hong Kong's government offices, for instance, protesters created a wall full of Post-it notes.

Some of the colorful messages simply read "I love Hong Kong." Others depict sketched umbrellas which have become the symbol of the revolution.

As my colleague Adam Taylor explained last week, "any visitor to Hong Kong will tell you that umbrellas are already a fixture of life in the city, essential not only for keeping yourself dry during the rainy spring and summer but also providing much-needed shade from the sun."

Throughout the protests, however, the umbrella became a political symbol -- and many have interpreted its use as metaphoric for the protesters' fight against the state security apparatus. "The umbrella serves as an appropriate metaphor for the nature of the protests, which is calm, determined, and defensive. Umbrellas could easily be turned into a weapon, but they are shown as open and benign," says Gaiter.

It is not only umbrellas that are being depicted. U.S. and Asian cartoon heroes are also represented among the Post-it notes in front of Hong Kong's government offices. Daniel Garrett, a researcher at City University of Hong Kong, argues that superheroes have been used as metaphors for the resistance against mainland China for years.  

According to Garrett, they are expression of a new political polarization:

Increasingly embedded within Hongkongers’ activism embodying identity politics and a repertoire of the new social movement are visual references to Western and Asian classical and new super heroes [...] who are perennially depicted challenging the power and ideologies of the dominant local ‘patriotic’ forces, i.e., pro-Beijing political parties and ‘red tycoons.’

Gavin Grindon, co-curator of an exhibition on art and design produced by grass-roots social movements, offers a similar, but more historical explanation. "During the Cold War, superhero comics, idealizing a strong individual, were one ideological means through which opposition to state Communism was articulated," he told The Washington Post.

Protesters also used painting and drawings to depict themselves and the main focus of their ire: Hong Kong Chief Executive Leung Chun-ying,

And during the protests, found objects were used to create art.

Some protesters even turned themselves into the art:

Not long after the protest started, people began posting photos and videos on social media sites under the hashtag #umbrellarevolution.

Kacey Wong, an assistant professor at the Hong Kong Polytechnic University, even started a design competition on Facebook to search for a common protest logo. Since then, submissions have been pouring in.

"Social media has certainly sped up the circulation of struggles among protest movements," says exhibition co-curator Grindon.