Several digital images that Microsoft has posted on its Web site to trumpet its new "I'm a PC" ad campaign were actually created on Macs, according to the files' originating-software stamp.

Four of the images that Microsoft made available on its PressPass site Thursday display the designation "Adobe Photoshop C3 Macintosh" when their file properties are examined. The images appear to be frames from the television ads that Microsoft will launch later Thursday.

One of the images is of a real Microsoft engineer, identified only as "Sean," who resembles John Hodgman, the actor who plays the PC character in Apple's iconic ads. Reportedly, Microsoft will play off Apple's own campaign -- during which Hodgman introduces himself with the line, "Hello, I'm a PC" -- with its engineer saying "Hello, I'm a PC, and I've been made into a stereotype."

Other images posted by Microsoft Thursday include shots of author Deepak Chopra; Canadian adventurer and educator Geoff Green, founder of Students on Ice Expeditions; and a shark-surround diver named "Meaghan."

Not all of the images on the PressPass site were generated on Macs. The sample print ads, which highlight the campaign's "Life Without Walls" slogan, were produced using the Windows version of Adobe Photoshop, according to their files.

The originating software and platform can be found in downloaded versions of the files using built-in tools on either a Mac running Mac OS X or on a PC running Windows.

In Windows XP, for instance, users can view the tag by right-clicking the downloaded file, selecting Properties from the drop-down menu, then clicking the Summary tab. "Adobe Photoshop CS3 Macintosh" appears beside "Creation Software."

On a Mac, after opening the downloaded file in Preview, users can see the tag by choosing Inspector from the Tools menu, clicking on the middle More Info tab, then clicking on the tab marked TIFF. "Adobe Photoshop CS3 Macintosh" appears beside "Software."

Microsoft's campaign is the creation of the Crispin Porter + Bogusky agency, part of a $300 million effort to revamp Windows Vista's reputation.

For more enterprise computing news, visit Computerworld. Story copyright Computerworld, Inc.