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As calls for a boycott of this year's Academy Awards over the all-white list of acting nominees intensifies, the academy's president issued a statement late Monday promising a more intense drive to diversify the largely white, male voting body. But not everyone agrees that the nominations are intentionally skewed.

"This is a difficult but important conversation, and it's time for big changes," Academy of Motion Pictures Arts and Sciences President Cheryl Boone Isaacs said in a statement released Monday night. "The Academy is taking dramatic steps to alter the makeup 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."

Isaacs' statement came after director Spike Lee and actress Jada Pinkett Smith each announced that they would not be attending the Feb. 28 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?!"

Lee made a point of writing in his post that the Academy Awards is only part of the problem in an industry with deep-rooted diversity issues. In his Governors Awards speech, Lee 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 Monday. "It's in the executive office of the Hollywood studios and TV and cable networks. This is where the gate keepers decide what gets made and what gets jettisoned to `turnaround' or scrap heap. This is what's important. The gate keepers. Those with `the green light' vote."

In a video message on Facebook, Pinkett Smith, whose husband Will Smith wasn't nominated for his performance in the NFL head trauma drama "Concussion," said it was time for people of color to disregard the Academy Awards.

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"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 by mid-Monday afternoon.

But "Boyz 'N the Hood" director John Singleton, the first African-American director nominated for an Oscar, disagreed.

“There’s only so many slots, though,” Singleton told Variety. “There are a couple of movies that may have (warranted attention) but … It’s all subjective. It’s almost like the lottery.”

“It’s like every year people complain. People even complain even when we have a lot of nominations," he said.  It is what it is. I’ve been in the game for 25 years. You never know — it’s the luck of the draw for you. To me, I’m not surprised. I’m not disappointed either, as much as other people are disappointed."

Actress Janet Hubert, who played Aunt Viv on Will Smith's TV show "The Fresh Prince of Bel Air," went after Smith's wife directly.

"People are dying. Our boys are being shot left and right. People are starving. People are trying to pay bills. And you're talking about some [expletive] actors and Oscars," she said.  It just ain't that deep."

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 percent from the year prior, a six-year low.

Isaacs has made a point of presenting a more inclusive show this year. The Feb. 28 broadcast will be hosted by Chris Rock and produced by "Django Unchained" producer Reginald Hudlin and David Hill.

The website NaughtyGossip reported Monday that Rock had come under pressure to pull out of hosting the show, but had not agreed to do so.

When Oscar nominations were announced Thursday, Isaacs acknowledged she was "disappointed" that all 20 acting nominees were again white and promised to "continue the conversation" on diversity. Isaacs has worked to diversify membership for the academy, which a 2012 study by the Los Angeles Times found is overwhelming white and male.

But on Monday, Isaacs was more explicit and promised an examination of the academy and a more intense drive to diversify.

Many awards handicappers expected nominations for Idris Elba of "Beasts of No Nation" and Benicio Del Toro for "Sicario." The N.W.A. biopic "Straight Outta Compton" also failed to earn a best picture nomination, despite some predictions it would. Ryan Coogler's acclaimed Rocky sequel "Creed" scored only a nomination only 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. Rev. Al Sharpton -- who last year met with former Sony head Amy Pascal following leaked emails that some viewed as racist -- on Friday lambasted the academy.

"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," said Sharpton.

The Associated Press contributed to this report.