A parenting and child development specialist has sued Walt Disney Co and its Pixar unit, accusing them of stealing from her the concept for their 2015 blockbuster movie, "Inside Out."

In a complaint filed on Monday in Los Angeles federal court, Denise Daniels said the animated film, featuring colour-coded characters representing individual human emotions, mirrors a children's programme called "The Moodsters" that she conceived and pitched to Disney every year from 2005 to 2009.

Daniels, who lives in Minnesota's Twin Cities area and has appeared on TV shows including "Today" and "Oprah," said she had an "implied-in-fact" contract with Disney requiring that she be paid from box office, DVD, Blu-Ray, iTunes and merchandise revenue from "Inside Out."

The film has grossed more than $850 million worldwide since its June 2015 release. Daniels said this "extreme success" was not possible without her work, and that Disney should pay her because it is "custom and common in the entertainment industry."

A Disney spokesman, however, said "Inside Out" was an original Pixar creation. "We look forward to vigorously defending against this lawsuit in court," the spokesman said.

Ronald Schutz, a lawyer for Daniels, declined to comment. Daniels was unavailable to comment.

The lawsuit is at least the second in three months accusing Disney of stealing a concept for a blockbuster film.

In March, the Hollywood screenwriter Gary Goldman, whose credits include the Arnold Schwarzenegger film "Total Recall," sued Disney for allegedly copying its Oscar-winning animated film "Zootopia" from his work.

"Inside Out" follows 11-year-old Riley, voiced by Kaitlyn Dias, as she tries to cope with her family's move to San Francisco from Minnesota.

It also shows her dealing with personifications of five emotions: Joy (yellow), Sadness (blue), Fear (purple), Anger (red) and Disgust (green), voiced by Amy Poehler, Phyllis Smith, Bill Hader, Lewis Black and Mindy Kaling.

Daniels said this resembled "The Moodsters," in which characters also had assigned colours: Happiness (yellow), Sadness (blue), Fear (green), Anger (red) and Love (pink).

According to her complaint, "Inside Out" director Pete Docter, former Disney Chief Financial Officer Thomas Staggs and several other Disney executives had access to her pitch.

No individuals were named as defendants.

In the "Zootopia" case, Disney has denied wrongdoing and asked a federal judge to dismiss Goldman's complaint.