As a budding director, Kasi Lemmons has always worked from the heart. Her first feature, "Eve's Bayou," was a film she wrote and directed about an especially dysfunctional but passionate black family in 1962 Louisiana. It opened with the line "Memory is a selection of images, some elusive, others printed indelibly on the brain. The summer I killed my father, I was 10 years old" and grew even more potent with every single scene. After garnering accolades at a few festivals and, more importantly, the boisterous adoration of Roger Ebert, "Eve's Bayou" became the most successful independent film of 1998.

So she knew whatever she did next, she'd have to feel just as strongly about it. "I was starting to get a lot of material and I didn't like anything," she said on a recent stopover in San Francisco to promote her new picture about following a mentally-ill homeless man embroiled in a murder mystery everyone else considers solved. "I didn't think I wanted to do anything written by somebody else when I'd had such a good auteur experience. But my agent talked me into reading it, and as soon as I read it, I knew it was me."

It is "The Caveman's Valentine," a provocative, stylized psychological thriller in which Samuel L. Jackson gives a brilliantly tormented performance as Romulus Ledbetter, a one-time musical genius who now lives inside a rock outcropping in a Manhattan park. His acute paranoid schizophrenia creates vivid delusions and visions that tax his remaining sanity when the body of a drug-addicted young drifter is found frozen to death in a tree outside his cavern. It's a lavishly and enigmatically atmosphere film, which is what I wanted to talk about when the striking Lemmons sat down for our interview, offering a warm smile that expressed both her intelligence and passionate enthusiasm for her latest project.

Q: What struck me most about this movie was how visually potent it was. You succeeded using unusual effects to illustrate Romulus' delusions. How did the visual style come about?

A: Just in reading (the script) it was very invocative, but it wasn't visually organized. Yet I had a sense just imagining it. Then reading the book -- the Y- and Z-rays (that Jackson's character thinks he sees) and what they look like -- George (Dawes Green, the author and screenwriter) would describe "a pernicious shade of green." So my director of photography and I are like, "What's a pernicious shade of green?" And we would actually hold gels to the light and say, "Hmmm, is this pernicious enough?" The Y- and Z-rays are huge gelled lights with a tiny bit of digital effect and a very, very strong color.

It was similar with "Eve's Bayou" as well, where you have memories and ghosts and flashbacks and visions, and you want to give those each a separate language, a separate feeling so the audience knows when they're in it. We knew that inside his skull was dark and gloomy, the feeling of a ruined basilica. I could picture that and I knew how I wanted it to look. It was a very difficult and ambitious thing to pull off on our budget.

Q: Which was what?

A: $13.5 million -- no matter what you may have heard to the contrary. (Laughs.)

The other thing is to be organized and prepared. You do all your visual preparation. We knew exactly what film stock (we wanted). For (Romulus's) "flashes of insight" we actually used a very strong film stock meant for shooting titles. It has an ASA of 6. You have to throw a lot of light at it. It's really kind of a tricky stock to work with, but it has a nice effect. Part of the tremendous fun for me is getting inside hallucination and trying to visually manifest that.

Anyway, we plan all that out. We test all the film stock, we test all the gels, and we're completely organized. So by the time the actors show up, Amy (director of photography Amelia Vincent) can go off with her crew and I can concentrate on the actors.

Q: The way you transitioned between what was going through Romulus's head and what was going on in the real world around him was just so beautifully handled. Especially the scene where he's at the piano after having crashed an art world party. He literally doesn't realize it's come out of his head and into the real world.

A: Yeah, we call that the "musical rampage."

Q: Sam Jackson is one of my absolutly favorite actors. I'll see anything just because he's in it. He seems to always have a really clear vision of his character and you can trust him and roll the camera.

A: You can trust him and roll the camera. You need to be very clear with your actor. The movie may hinge on something for the director that isn't the exact same thing for the actor, so you want to discuss all that ahead of time. But it works best with a magnificent talent like Sam's to be there for support, to watch his back, rather than try to impose a performance on him, because he knows what he's doing.

For example, I knew that "Eve's Bayou" (in which Jackson played the philandering, allegedly abusive father) wouldn't be a complete success for me if Louis Baptiste wasn't completely sympathetic. That's the type of thing where Sam is great casting because Sam can be a sympathetic hit man!

Q: What's your favorite Sam Jackson movie besides your own?

A: (Long pause.) "Pulp Fiction?" I don't know! "Jungle Fever!" "Jackie Brown!" I'm a fan! I'll say "Jackie Brown," because there was something about that guy. He's such a bad person, but you still kind of like him anyway. That was something to pull off. But then, the redemption of Jules in "Pulp Fiction" -- it was such a well-written character.

Q: Did you do any kind of research into homelessness to better understand his character?

A: I did not do any research for this character, but the first film I made in film school was about homeless people and I did a tremendous amount of research then. So I had a background of having really done a lot of research and having spent a lot of time with homeless people. So when I read the script, I was like, this is amazing that this came along.

Q: How did you get into directing initially?

A: Well, when I went to film school I thought I was going to make documentaries. I didn't really go to film school to direct dramatic features. I went to learn cinematography because I thought I wanted to make documentaries that I shot myself. I got into filmmaking because after writing "Eve's Bayou," in the process of shopping it around, I began to be afraid that somebody was going to mess it up.

Q: (Laugh.)

A: I began to realize it was a delicate piece of material. It was easy to misinterpret or to just throw off balance. To me it had a very fine balance and I woke up one day and thought I'd rather put it in a drawer than have somebody mess it up. It would be better to direct it myself.

So I told my producer and he almost fell over. But being a risk-taker and an idealist, he said, "OK, I'll produce a short film for you -- not like those films you made in film school, but on 35mm with a full crew -- and we'll see how you do. And why don't you make is a short film that's going to remind people what it is you want to do in 'Eve's Bayou.'" So we made a short film called "Dr. Hugo," where I found my DP who has shot all my movies, and we came up with a style that was apparent even in that short film. On the strength on the short film -- although it's very quaint to look at it now -- from the short film and the script, Sam Jackson signed on in support of me as a director. So I kind of fell into it trying to protect "Eve's Bayou."

Q: Had you sent it to Sam Jackson just hoping against hope?

A: Yep.

Q: Did you know him before?

A: I did. I'd known him for years, from around (Hollywood) -- in that black show business is small and tight and we all know each other. So Sam and I had known each other enough to like hug at parties, but not like long conversations.

Q: So it wasn't like, "Please Mr. Jackson! Please read my script!"

A: No, it was like "Please, Mr. Jackson, you remember me! Please read my script!" (Laughs.) It was still a leap of faith. But he didn't prejudice himself because it was my first time or because I was a woman. He went with the idea, which was very brave of him.

Q: At what point did you realize that "Eve's Bayou" was going to be the enormous success that it was? How far into its release were you suddenly going, "This is happening!"

A: It was very, very interesting -- and very similar to this film. We tested badly. We didn't get into Cannes, we didn't get into Venice, we didn't get into the New York Film Festival. The guy who was going to release it was like, "Tell me why I should release this movie." I mean, it was terrifying. We thought, oh my god! We just didn't get it. My editor and I would sit there and go, "But we love it! Are we crazy?"

Q: Then?

A: Then we got into Telluride and we thought, Oh my god! A festival! Then we got into Toronto. When we went to Telluride it was hot from the lab and nobody had really seen it but the test audiences. We showed the film, sitting in the back row in terror. All of us involved with the film were in the back row just stiff. Then they stood up at the end of the film and applauded. Oh my god! Then they sat down and waited for the end of the credits, then they stood up again. By this point I was just crying. It took me a long time to get it together to leave the theater. When the audience had filed out, I went out to the parking lot and the audience had waited in the parking lot, and when I came out they clapped again! So I thought, well, some people might really like it!

Then Roger Ebert saw it in Toronto.

Q: And he really went out of his way to champion the film.

A: He was our champion. But we still didn't know and it was like our second or third week of release when the marketing guy called me up to say, "I don't know when it's going to stop!" And I thought, OK, this is good.

Q: OK, let's get back to "The Caveman's Valentine." Working from a screenplay by the novelist, you must feel obligated in many ways. Was he around? Were you working with him in any way?

A: We had several meetings, but we didn't like, sit down together (and work). I would try some things out and show him, then we would argue about it. (Laughs.) We went back and forth, but it was really a George thing. It was a George script and a George book. He's really responsible for the writing of "The Caveman's Valentine," even though I worked to develop it for years and we worked together on the very last draft of it. But it very much remained a George Dawes Green script.

Q: Are you going to keep acting or are you going to focus on directing?

A: I'm definitely going to focus on directing, but I would like to keep acting as well just to keep the skills sharp and keep honest.

Q: Do you have a next project in mind?

A: As a director? Yeah, I've got a few. We'll have to see how it shakes out. So many things go into making a film happen. So many things can go wrong, especially in casting a big cast. I'm really, really hoping this one project comes together. But there are a lot of different elements that have to come together.