Maggie Gyllenhaal as Clara, Michael Fassbender as Frank and Domhnall Gleeson as Jon in “Frank.” (Magnolia Pictures)

The concept behind the movie “Frank” is strange. An eccentric musician (played by Michael Fassbender) masks his identity with an enormous papier-mache head that features painted expressionless eyes and a dollop of neatly parted black hair that makes him look more like a puppet than a rock star. The only thing that isn’t so strange is the mainstream pop music he’s trying to make.

But as odd as it may seem, “Frank” is inspired by a real person, the late British musician Chris Sievey, who took the stage name Frank Sidebottom, did wear a huge head for performances and was a semi-famous musician in England. The film’s script and lead characters are loosely based on author and journalist Jon Ronson’s experiences on tour with Sidebottom’s band from 1987 until 1990, which he first wrote about for the Guardian in 2006 and then elaborated on for a book this year. Inspired by both Sidebottom’s legacy and cloud of mystery that remains, Ronson, whose work includes “The Psychopath Test” and “The Men Who Stare at Goats,” is now taking his story to the screen, with the help of screenwriter Peter Straughan and a little imagination.

Before the film’s one-week run at E Street Cinema beginning Aug. 22, we tried to clear some things up with Ronson over the phone, as he talked about his friend, what it’s like to write a character that’s based on yourself and his theory on that head.

How much of what happens in the film are things that you actually experienced with Frank?

Well, there’s this character, Jon, that’s based on me and he joins this band as a keyboardist and so the first 10 and 15 minutes are pretty biographical. And then what happens is that they all go off to a home in the middle of nowhere to make a record, which is something that we never did. I was inspired by these stories of Captain Beefheart as this cult leader and someone who would go off into the middle of nowhere to write music, and then in the movie, the character of Frank is much more like Daniel Johnston [the iconoclastic, bipolar Austin singer-songerwriter], who is a deeply troubled person. The most glaring difference is really in the music. Frank in the movie has original, good songs and is very serious. In real life, he was playing covers of, like, Madonna. . . . The real Frank was much more comedy.

Author and journalist Jon Ronson. (Barney Poole/Courtesy of Falco Ink)

Was fictionalizing it then a way to ease up on the struggle to find who he actually was?

I think so. He’d be quiet and polite. Then, on the other hand, he could be manic. Also, politically, he died in 2010 [of cancer at age 54] so I wanted to be sensitive about that. I didn’t want to write a character on Chris. It’d be too invasive. As a journalist, it was really hard to avoid writing about the real Chris. My writing partner for this, Peter Straughan, would look at me with this patient look and say, “Jon, it’s okay, we can make things up.” It was like learning how to do what we do in a completely different way. In journalism, it’s about getting to the truth, and in fiction, it’s about getting to the opposite of that, but still beautifully.

As far as research, you’ve mentioned Captain Beefheart and Daniel Johnston, so in your mind, what themes linked those people to Frank?

I think it’s just being naturally on the margins. I remember when I interviewed Randy Newman and he basically said to me, “I’m stuck being me.” I mean, he’s selling millions of records but I thought it was interesting being trapped in who you are. For Daniel Johnston, he never had a chance at being a mainstream pop star. Even if he wanted to, he couldn’t. It’s like with him and Beefheart and Chris, they were all forced into a position in pop culture because of what was going on inside their heads. I liked the idea that all these characters were forced to be on the margins of popularity and, in fact, reveled in that. I mean, if Frank had been on “The X Factor,” he would have been mocked and laughed off stage.

You are one of the main characters in this so was writing a character based on yourself in any way unsettling?

Well, what I actually did was make him more despicable than I was in real life. That was just huge fun to play with me. I think a lot of people, when they write what they were like in a memoir or whatever, make themselves more awesome than they ever were and for me, turning myself into a villain was great fun and in some ways easier to do. You know, you have to have chutzpah to write yourself into a better, more awesome person than who you were, but no chutzpah is required to turn yourself into a monster.

Since you knew him and were around this figure, and I say this with the utmost respect, . . . did it ever get creepy?

Well, in the movie, it certainly gets creepy. [Laughs] The blank stare, you know. In real life, I was just sort of mesmerized and intrigued. As a young man who was already feeling a bit insecure and a bit, sort of, off, that was magnified when someone’s wearing a big fake head staring at you all the time. You’re totally enraptured by the mystery of it. I’ve also got to say that Frank was slightly easier to be around than Chris. Frank was so one-dimensional and sweet. He was actually easier to talk to with the head on.

Do you have a theory as to why? Was it just a constant sense of being socially uncomfortable for him and this huge head made him feel less obliged to play by society’s rules? Michael Fassbender, in his interview on “The Colbert Report” the other night, called the head “liberating.”

I think it is liberating! I put the head on the other night and I kind of didn’t want to take it off. Your anxiety turns completely off. Also, the idea that Chris’s Frank was always so innocent and childish, and so I feel like the head can take you back to a place before you got responsibilities. Chris owed all this money in tax and definitely took too much speed and drank too much, and Frank was like a child. I think it was hard for him to separate the two parts of himself. Sometimes he’d take the head off right away and then other times he kept it on.

Do you think he would be happy with the film and the legacy he’s left behind in your work?

I really think so. I think this would have been a personal high for him. Because it’s a really good film, and it introduces him and the “real” Frank Sidebottom, but it in no way does it reveal him. At one of the screenings for this, I leaned over to his oldest son and asked him, “Do you think he would have liked all of this?” and he said that he would have loved it. Chris knew it was going to be fictionalized and I think he would have respected that decision. The one thing that mattered most of all is that it would bring a whole new audience to him, and I think we’re doing just that.

Frank Opening Friday, Aug. 22 at Landmark E Street Cinema. Rated R for language and some sexual content. 95 minutes.