PORTUGAL • As a child growing up in Santa Maria da Feira, Portugal, Tiago Santos never took crayons to school. He asked his classmates to pass him the correct ones because he had trouble choosing crayons of the right colour.

Today, Mr Santos, 34, knows he suffers from colour blindness.

It seemed so easy for others, but when he tried colouring trees or skies, his classmates laughed at the crayons he chose.

"I thought I did not 'get' colours, just like some people struggle with understanding mathematics," Mr Santos said. "I was embarrassed."

Portuguese designer Miguel Neiva, 49, had a friend like Mr Santos in school. At the time, he made fun of him.

Now, he fights discrimination with a special "alphabet" he designed.

In 2008, Mr Neiva presented ColorADD, an identification system where each of the three primary colours (red, yellow and blue) is linked to a basic shape (triangle, slash and inverted triangle).

Ten years on, ColorADD is included on the garment labels of several Portuguese brands, on colour pencils, card games and transport systems.

In 2014, a group of Portuguese programmers even used it to create an iPhone app to label colours automatically through a smartphone camera. It was praised by the United Nations for its global impact.

Colour blindness affects one in 12 men and one in 200 women worldwide.

"More than a code, the projects that come from ColorADD made it possible for me to stop hiding my condition. They give me independence in a society that lives by colours," said Mr Santos, who uses the smartphone app daily.

Mr Neiva, who believes his not being colour blind helps to make the code universal, said: "I don't want to create special products for people who are colour blind.

" I want everyone to understand colours."