Charles re-recorded some of his hits for the film

Charles, one of the US music scene's most influential figures, had agreed to the film, Ray, before his death.

Actor Jamie Foxx, who stars as Charles, sings some of the film's songs, although Charles also re-recorded many of his old hits for the movie.

The film has been directed by Taylor Hackford. A soundtrack will be released in August.

"Ray Charles OKed the script, and he was 100% supportive of what we were doing in telling his life story," music supervisor Curt Sobel told Billboard magazine.

"Jamie only sang on the set, not in the studio. We felt that many of the older songs needed to have Ray's vocals," he said.

Development

"The way the script was written, they told Ray's life through the songs," Mr Sobel said. "You'll hear a song like Hit the Road Jack in a scene when Ray has a fight with his wife Margie."

Charles, who died from liver problems, had a musical career lasting nearly 60 years, despite becoming blind at the age of six. His hits included Georgia on My Mind and I Can't Stop Loving You.

The film had started as an independent production, until Universal Pictures joined the project in March. It had been in development for 16 years.

Charles gave his blessing to the film before his death

Mr Sobel said his initial meeting with Charles was his favourite memory of working on the film.

"I was there the first time Jamie met Ray. Jamie was tongue-tied at first, but Ray was so warm and giving of himself. They ended up sitting at pianos side by side and playing music and telling stories.

"I happened to bring a digital video camera with me to record those meetings. We made a 'making of' documentary, which will probably end up on the Ray DVD."