Radiohead's lead singer Thom Yorke, performs at the Ford Amphitheatre on Tuesday night. [JOHN PENDYGRAFT | Times]

TAMPA -- From the look of the zombiefied masses at a near-sold-out Ford Amphitheatre Tuesday, you'd think the 17,500 in attendance were bored or stunned or undead.

But that's exactly what a crowd should look like at a Radiohead show. If you came to hear the famously obtuse British rock band bust out the dance jams or incite arena-rocking sing-alongs -- or, um, play the stuff you know -- you no doubt want your money back.

But if you came to quietly enjoy a tech-nerdy quintet work out its Kafka-esque angst via less obvious tracks that shifted from frustrating to quirky to soul-clutching gorgeous, you floated from the venue blissed-out and satisfied.

(Oh, and if you came to gawk at a state-of-the-art light show featuring dozens of floor-length strobes that seemingly danced in unison to each song -- exploding in orange fireworks to the new "Reckoner," morphing into an underwater paradise for "Weird Fishes/Arpeggi" -- wow, dude, that was one of the trippiest things I've ever seen.)
   
With the mind of a mathematician and the voice of a wounded angel, Radiohead frontman Thom Yorke proved once again to be a beautiful misfit, a Lewis Carollian character obsessed with alienation and alien nations, strange equations and fake plastic trees.

Oh yeah, he's mad as a hatter. But man, can he wail, sending shivers through the throngs with soaring, searing readings of 1997's "Airbag" and 2000's prickly "Everything in Its Right Place." He also showed a rather refreshing puckish side, hamming it up for a piano-mounted fish-eye lens during the comically defiant "You and Whose Army?"

Much hullabaloo ensued last year when Radiohead ditched its longtime label, EMI, and decided to sell new album "In Rainbows" themselves. For the digital version of the album, they even let fans pay whatever they wanted.

It made a swell business story, for sure. But the main reason it worked is because Yorke & Co., even two decades after forming, have been able to reinvent themselves to thrilling, and at times confounding, extremes.

They've literally turned their formerly raging, melody-rich songs inside out, and upside down, exploring their odd, anti-pop urges with bleeps and bloops and whatever else they can find in their addled pysches.

Guitarist Jonny Greenwood spent most of the night trying to make his guitar and his keyboard sound like anything but a guitar and a keyboard. For "There There," he freaked out on his axe, making those strings sing out like a swarm of sick birds. On "Lucky," from 1997's masterful "OK Computer," he conjured a heavenly landscape for Yorke's operatic malaise.

The brainy boys kept things relatively downbeat, but they did decide to let loose now and then. The new "Bodysnatchers" sounded like a surf-rock rumbler done by the Talking Heads. And a ferocious encore version of "Just," from 1995's even-more-masterful "The Bends," proved that when these guys cut loose, they can rock as hard as anyone.

Of course, the crowd pretty much absorbed those upbeat cuts just like all the others: swaying, nodding, smiling on the inside.