Postcards became popular at the turn of the 20th century, especially for sending short messages to friends and relatives. They were collected right from the start, and are still sought after today by collectors of pop culture, photography, advertising, wartime memorabilia, local history, and many other categories. (Source)
I recently came across this collection of vintage postcards from 1900 - 1910, which showcases "Women's Beauty" on Bored Panda.
|Gypsy Girl with Mandolin
Source: Bored Panda
This led me to browse other sites for postcards, and found a huge range in style and composition, from humorous to romantic to erotic. It struck me that poetry and picture postcards have something in common, when it comes to brevity and striking images.
|World War 1 Postcard
|World War 2 Postcard
Do some browsing of your own, or select one of the postcards I have used by way of example, and write a poem inspired by the picture, or if you prefer, the message written on the reverse side. I am not setting a word limit, but in the spirit of postcards, I would encourage brevity.