The Oscars need a major shake-up, the Academy Awards chief has said, amid a growing row over the lack of black stars in this year's nominations.
Academy of Motion Pictures Arts and Sciences president Cheryl Boone Isaacs issued a statement promising more diversity after Spike Lee and Jada Pinkett Smith both announced that they will boycott this year's ceremony.
In a lengthy Instagram post, Lee said he "cannot support" the "lily-white" Oscars.
Noting that he was writing on Martin Luther King Jr Day, Lee - who in November was given an honorary Oscar at the Governors Awards - said he was fed up: "Forty white actors in two years and no flava at all," he wrote. "We can't act?!"
In a video message on Facebook, Pinkett Smith also said she would not attend or watch the Oscars in February.
Pinkett Smith, whose husband, Will Smith, was not nominated for his performance in the NFL head trauma drama Concussion, said it was time for people of colour to disregard the Academy Awards.
"Begging for acknowledgement, or even asking, diminishes dignity and diminishes power," she said. "And we are a dignified people and we are powerful."
She added: "Let's let the Academy do them, with all grace and love. And let's do us differently."
The video had amassed 4.5 million views by mid-Monday afternoon.
Last year's all-white acting nominees also drew calls for a boycott, though not from such prominent individuals as Lee and Pinkett Smith. Whether it had any impact or not, the audience for the broadcast, hosted by Neil Patrick Harris, was down 16% from the year before - a six-year low.
Ms Isaacs has made a point of presenting a more inclusive show this year. The February 28 broadcast will be hosted by Chris Rock and produced by Django Unchained producer Reginald Hudlin and David Hill. On Saturday, Rock, unveiling a new promotion for the broadcast, called the ceremony "The White BET Awards".
When Oscar nominations were announced last Thursday, Ms Isaacs acknowledged she was "disappointed" that all 20 acting nominees were again white and promised to "continue the conversation" on diversity.
She has worked to diversify membership for the Academy, which a 2012 study by the Los Angeles Times found is overwhelmingly white and male.
But on Monday, Ms Isaacs was more explicit and promised an examination of the Academy and a more intense drive to diversify.
"This is a difficult but important conversation, and it's time for big changes," she said in a statement released Monday night.
"The Academy is taking dramatic steps to alter the make-up of our membership. In the coming days and weeks we will conduct a review of our membership recruitment in order to bring about much-needed diversity in our 2016 class and beyond."
Many had predicted nominations for Idris Elba for Beasts Of No Nation and Benicio Del Toro for Sicario.
The NWA biopic Straight Outta Compton also failed to earn a best picture nomination, despite some predictions that it would.
Ryan Coogler's acclaimed Rocky sequel Creed scored only one nomination - for Sylvester Stallone.
Lee's own movie, the Chicago gang violence hip-hop musical Chi-Raq - celebrated by some and scorned by others - also went unnoticed.
The hashtag OscarsSoWhite, created last year, was quickly resurrected online following the nominations.
The Rev Al Sharpton - who last year met former Sony head Amy Pascal following leaked emails which some saw as racist - lambasted the academy on Friday.
"Hollywood is like the Rocky Mountains - the higher up you get the whiter it gets, and this year's Academy Awards will be yet another Rocky Mountain Oscar," he said.
In his post, Lee made it clear that the Academy Awards is only part of the problem in an industry with deep-rooted diversity issues. In his Governors Awards speech, he said "It's easier to be the president of the United States as a black person than be the head of a studio."
"The Academy Awards is not where the 'real' battle is," wrote Lee on Tuesday. "It's in the executive office of the Hollywood studios and TV and cable networks. This is where the gatekeepers decide what gets made and what gets jettisoned to 'turnaround' or scrap heap. This is what's important. The gatekeepers. Those with 'the green light' vote."