Image copyright Alamy Image caption Dan Robbins with a paint-by-numbers self-portrait

Dan Robbins, the artist behind the paint-by-numbers craze that swept America, has died in Sylvania, Ohio, at the age of 93, his son told the AP news agency.

He was working at a paint products firm in the 1940s when he invented the kits.

By the 1950s millions were being sold across the US every year.

His inspiration for the idea came from Leonardo da Vinci, who used a similar method when teaching his apprentices how to paint.

Mr Robbins first joined Palmer Paint, a company selling children's paint sets, after serving in World War Two.

Image copyright Getty Images Image caption Mr Robbins invented paint-by-numbers in the 1940s

In a post-war era of increasing leisure time, the company's owner, Max Klein, asked Mr Robbins to find a way to market the paint to adults.

"I remembered hearing that Leonardo used numbered background patterns for his students and apprentices, and I decided to try something like that," Mr Robbins told an audience at the Chicago gallery Intuit in 2004.

He put together an abstract still life, a mix of "Picasso, some Bracque and some Robbins". Mr Klein told him he hated the painting but liked the idea of painting by numbers.

The kits, which contained canvasses with printed numbers corresponding to numbered paints, brushes and a palette, originally cost $2.50 (£2).

The paintings ranged from landscapes to bullfighters, ballerinas to kittens. The company's most popular work was The Last Supper.

In 2013, Mr Robbins was asked if paint-by-numbers counted as art. "No, it's only the experience of picking up a brush," he said. The aim, he added, was to recreate what a real artist goes through.

Image copyright Alamy Image caption Mr Robbins with the first paint-by-numbers design, called Abstract No. 1

Sales took off in the 1950s, reaching $20m (£15m) in 1955. But other brands soon caught on to the craze and the market became saturated. By 1957, sales were significantly down and Mr Klein was forced to sell up.

Mr Robbins stayed on when the company was bought out by General Mills, later moving to a Chicago cake decorations manufacturer. He retired in 1973 and started painting on a freelance basis.

A collection of paint-by-number artworks were exhibited at the prestigious Smithsonian Institution's National Museum of American History in 2001.