His photo “Hidden smile” featuring 70-year-old boat rower Bùi Thị Xong of Hoi An has been published on a number of US newspapers and magazines including the Los Angeles Times, the Daily Mail, and National Geographic, and was voted the world’s most beautiful photo of a woman. The artwork impresses viewers with the positive toothless smile in the old woman’s wrinkled face.
 

The photo "Hidden Smile"

Once the photo is showcased to the world, old lady Xong has become popular. She has followed Réhahn to Hanoi and Ho Chi Minh city to attend many exhibition as well as activities to promote Vietnamese culture.  
Photographer Réhahn revealed, Công Nguyễn – a 37-year-old citizen of Vietnamese origin living in Melbourne has bought his famous photo. The Hidden Smile has originally been printed into three copies.  The French photographer then sent the revenue from this to the fund for building Museum of Co Tu Culture, which is expected to debut by the end of 2018.
The second copy of the photo is priced up to US$ 50.000. Réhahn said 80% of revenue from this activity will be contributed to build Museum of Co Tu Culture.
According to the French photographer, meeting Xong makes him famous. “When I take the photo of her, I have never thought it could change our life”, he said.
Earlier, in 2015, another photo by Réhahn capturing an ethnic girl who communicates with an old elephant in Tay nguyen was sold for Eur 10.000. This photo at the time was displayed at his individual exhibition in France.