New software designed to make airport security scanners less intrusive debuted at the Las Vegas airport Tuesday, a response to last year's uproar from passengers who thought the blurry but revealing images were an invasion of privacy.
The machines now produce a gray, cookie-cutter outline of the human form. The silhouette appears on a screen about the size of a laptop computer that is attached to the scanning booth.
If a passenger is cleared by the scan, the screen will flash green with an "OK." Suspicious items detected by the scanner appear as little boxes outlined in red, showing their location on generic front and back silhouettes on the screen.
Passengers who trigger an alert, and anyone who refuses to go through the scanners, will receive the rigorous frisking that has drawn sharp objections.
The new software is expected to debut soon at Reagan National Airport and in Atlanta. If it does as well in the field as it has in testing, it could be installed in the 486 scanners now in use at 78 major airports, the Transportation Security Administration said.
"We believe it addresses the privacy issues that have been raised," said John Pistole, head of the TSA. "It's basically a software modification to existing equipment, so there's very little cost."
Robin Kane, who heads the TSA's technology office, said that once the less-invasive approach is proved effective, then the controversial monitors, on which a TSA officer reviews scans in a private screening room, will be removed from all airports.
The images produced by the current software led to an uproar over privacy concerns. Pistole had said in the fall that he wanted to see modifications, but the technology that was being tested yielded too many false positives. Many passengers found the alternative "enhanced" pat-downs by TSA agents even more disturbing.
In the demonstration at National on Tuesday, "passengers" filed through the scanner, some of them producing gray silhouettes with green "OK" screens, others producing silhouettes with boxes noting where the machine detected something hidden.
Kate Hanni, founder of the California-based group FlyersRights, called the new software "a great step forward."
"We're grateful to the TSA for addressing these issues that were of concern to so many people," Hanni said. "But privacy was our secondary issue. Our primary concern about the body scanners is that they are ineffective. We're also concerned about the possibility of surges in radiation."
Two types of scanning machines - backscatter and millimeter wave - have been installed at airports. Both machines produce the kind of full-body images that attracted controversy; they work by bouncing X-rays or radio waves off skin or concealed objects.
According to the TSA, the new software is being tested on millimeter wave machines, but the agency plans to test similar software on backscatter units.
"It's sort of like developing software for an Apple computer and a PC," TSA spokesman Nick Kimball said. "The software has to be different."
Currently, 239 millimeter machines are in operation at 40 airports; 247 backscatter models are in use at 38 airports.
Although this could become the first wide-scale application in the United States that marries scanner technology with software that produces a less-than-graphic image, the concept is not new.
Similar scanning software has been used at Schiphol airport in Amsterdam, but the TSA said it didn't meet U.S. standards.
Willard "Bill" Wattenburg, a former nuclear weapons designer at the Lawrence Livermore National Laboratory in California, was rebuffed four years ago when he offered a software program to distort scanner images so they would reveal dangerous objects but not body contours.
"We knew this was going to create a controversy the minute we first heard that they planned to use scanners," Wattenburg said.
Use of the scanners infuriated a vocal minority of Americans who pressured the Obama administration and Congress to find a less-intrusive method for trying to ensure air safety. But most people surveyed last fall - 81 percent in a CBS poll and nearly two-thirds in a Washington Post-ABC News poll - said they supported their use.
Obama asked Pistole whether a less-intrusive approach could be developed. Pistole was quizzed on Capitol Hill but remained stalwart, insisting that the scanners are necessary in the defense against inventive terrorists obsessed with attacking aviation.
Further indignation arose over the rigorous pat-downs performed on those who refused to go through the scanners or who appeared to be carrying contraband, with one House member telling Pistole he wouldn't want his wife to be subjected to that.
Secretary of State Hillary Rodham Clinton said that if faced with the choice, she would opt for the pat-down rather than the scanner because she understands "how difficult it is and how offensive it must be for the people who are going through it."
A California man became an instant folk hero last year after he threatened a San Diego TSA agent with arrest if "you touch my junk" during a pat-down.
Despite drawing advance attention, a protest planned for Thanksgiving weekend that organizers had hoped would draw attention to privacy issues fizzled.