If you've ever wondered why Harry Connick Jr. joined the crew of judges on "American Idol," the Fox network talent show, well, it had little to do with money.

Presumably, Connick - multi-platinum singer-songwriter, film star and a visionary activist whose humanitarian efforts in the post-Katrina renaissance of New Orleans are humbling - has plenty of cash. Rather, the genuine and convivial Connick, who performs Sunday in the Grand Theater at Foxwoods, likes the idea of giving back.

When Connick was only 7 years old in his hometown of New Orleans, his parents introduced him to a family friend, James Booker, the troubled but undeniably brilliant pianist who died 31 years ago today. Booker, himself a former child prodigy whose intricate amalgam of classical, New Orleans R&B and funk remains utterly unique and criminally under-appreciated, took young Connick under his wing and taught him piano in a gentle and encouraging fashion - and Connick will never forget it.

Earlier this week, speaking by phone in his melt-butter Crescent City drawl, Connick remembers, at first, just being impressed by how kind Booker was. Then, by 12, as Connick grew more accomplished at rudimentary piano, he suddenly saw and heard Booker in a new context. "(Booker) went from being this really nice guy who happened to play piano to 'Wait a minute! How do I do that?!' He'd show me stuff that, to this day, is very, very hard to do."

Later on, after Connick studied jazz with Ellis Marsalis and started his own career, Booker continued to have an influence. "If he was appearing at Jazz Fest and saw me, he'd ask me to come up and play and always made me feel welcome, like I was an equal. He'd say, 'You're studying with Ellis; I wish I could do that jazz stuff y'all do' - like James Booker could learn something from me - which was absolutely not the case!

"But that was his way. He was very wise and knew what it meant to make you feel like you were improving and getting good. He was just so kind and supportive."

Years later - a bona fide star - Connick perhaps surprised fans and industry insiders when he accepted an offer to be a judge on "Idol."

He explains, "There were a lot of reasons to do it, but I remembered James Booker and I just like the idea of being around young musicians - whether it's a master class or 'American Idol.'"

Indeed, none of the celebrity judges in "Idol's" long run have offered the sort of constructive advice - frequently discussing music theory and composition as well as proper vocal and microphone technique - that Connick routinely dispenses in genial and witty fashion.

"This is within the realms of what I can do as an entertainer," Connick says. "In terms of listening to 600 (competitors) and narrowing it down to 24, and telling them what will help them in a career, it's just a lot of fun. I try to present a different aspect of show business because, really, 95 percent of them don't know anything about music."

Connick describes a music industry full of computerized beats, auto-tuned vocals and a very formulaic approach to pop songwriting. "That's all fine and good until the day they DO need to know technique and something about the way the business works," he says. "And I just remember that I had an incredible experience growing up - being taught and mentored by people like James and Ellis. If I can share some of that and have some fun, that's a good thing."

Another aspect to the "Idol" judging, Connick says, is that it doesn't heavily mortgage his time. Which is important since he has plenty of other projects going on.

This latest tour, for example, is in support of two albums he released almost simultaneously late last year. One is called "Every Man Should Know" and is a set of observational, original and affectionate tunes delivered in a somewhat Sinatran tone of middle-aged wisdom and maturity.

"I don't know that I would call the songs reflective," Connick says. "It's just my age, I think, and at this point this is the way I play and sing and write. If I'm doing anything I wouldn't have done 10 years ago, it would be from the standpoint of recording technique. Back then, I was a little too much of a purist and perfectionist, and with this album I think I just relaxed a bit and let it breathe a little."

The other album, "Smokey Mary" - named after an eight-unit parade float from Connick's Krewe of Orpheus Mardi Gras organization - is an exuberant and celebratory collection of self-penned funk and carnival songs. If vastly different than "Every Man Should Know," it nonetheless helps point out Connick's wide-ranging stylistic curiosity and musical DNA. Interestingly, the two albums didn't start out as separate projects.

"It was time to make another record and I just started writing tunes," Connick says. "I ended up with so many that I did something I'd never done before. I went into my record label, the office of the president, and sat down and basically held everyone captive while I played them 25 tunes." He pauses and chuckles. "Frankly, I was sort of impressed by the variety of styles.

"But the response was heartbreaking. The president said, 'How do you expect me to sell this?'

"I said, 'Well, I wanted to take people on a musical journey.' I had to take a step back and admit he was right in terms of selling albums. But I kept trying. 'How about a double album?' 'Nope. They don't sell.' 'Okay, how about just releasing two CDs?'

"And then they finally said, 'You can do that.'" Connick takes a deep breath and exhales. "I just don't think of things like that. I make the music and expect the label people to figure it out!"

The current tour probably would have started sooner except for the fact that Connick was wrapping up his latest film, "Dolphin Tale 2," in which he reprised his popular role as marine biologist Dr. Clay Haskett. In another bit of encore casting from the original movie, Kris Kristofferson returned as Clay's father, Reed Haskett. It actually marks the third time Kristofferson's played Connick's dad; the pair were father/son in a 2013 holiday film called "Angels Sing."

The idea of Kristofferson and Connick - both of whom would be quick to say their "day jobs" are as musicians - spending so much time together on slow-moving movie sets suggests plenty of time to discuss the art of songwriting.

"That's actually not the case," Connick says. "As well as I know Kris, and as much as I'd love to talk a lot with him about music, I never wanted to bother him. I mean, think about his life. He was a Rhodes Scholar, a boxer, an amazing songwriter ... It just seemed there was no way to gracefully get into that."

But Connick describes a concert he played one night after a long day on the set for "Dolphin Tale 2." Some of the cast members showed up and Kristofferson was among them.

"I'm not bragging because I don't mean to," Connick says in a tone of excitement, "but they came backstage and Kris had this look on his face. He said, 'I had no idea, man.' For a few minutes, we talked about music in my dressing room. I mean, I knew all about him and his songs - he's Kris Kristofferson! - and it was just really nice."

Harry Connick - ever the grateful student.

IF YOU GO

Who: Harry Connick Jr.

What: Touring behind his recent "Smokey Mary" and "Every Man Should Know" albums

When: 7 p.m. Sunday

Where: Grand Theater, Foxwoods Resort Casino

How much: $85 and $115

For more information: 1-800-200-2882, foxwoods.com