A tattoo artist paints on a model during the 21st International Tattoo Convention in Frankfurt, Germany, March 22, 2013. The Tattoo Convention kicked off on Friday and will last for three days. (Xinhua/Luo Huanhuan)

A man attends the 21st International Tattoo Convention in Frankfurt, Germany, March 22, 2013. The Tattoo Convention kicked off on Friday and will last for three days. (Xinhua/Luo Huanhuan)

A man attends the 21st International Tattoo Convention in Frankfurt, Germany, March 22, 2013. The Tattoo Convention kicked off on Friday and will last for three days. (Xinhua/Luo Huanhuan)

People attend the 21st International Tattoo Convention in Frankfurt, Germany, March 22, 2013. The Tattoo Convention kicked off on Friday and will last for three days. (Xinhua/Luo Huanhuan)

A tattoo artist paints on a model during the 21st International Tattoo Convention in Frankfurt, Germany, March 22, 2013. The Tattoo Convention kicked off on Friday and will last for three days. (Xinhua/Luo Huanhuan)

A person is being tattooed by a tattoo artist during the 21st International Tattoo Convention in Frankfurt, Germany, March 22, 2013. The Tattoo Convention kicked off on Friday and will last for three days. (Xinhua/Luo Huanhuan)

A person is being tattooed by a tattoo artist during the 21st International Tattoo Convention in Frankfurt, Germany, March 22, 2013. The Tattoo Convention kicked off on Friday and will last for three days. (Xinhua/Luo Huanhuan)

A tattoo artist paints on a model during the 21st International Tattoo Convention in Frankfurt, Germany, March 22, 2013. The Tattoo Convention kicked off on Friday and will last for three days. (Xinhua/Luo Huanhuan)