“Undelete”: JPG Dept.

Old heads may remember the DOS “undelete” command.

The New York Times reports that software has been developed that can do the same thing for deleted digital photographs. Read the full story here.

From the story:

“Now, is smart enough to find and reassemble fragmented digital photographs, even when the directions for locating them have been deleted. The feat is similar to assembling a million pieces of a jigsaw puzzle with no guiding box-top image.”

The undelete command worked because, when a user deletes the file, the file’s content is not deleted. Rather the marker that tells the operating system where to find the file is deleted. This allows the operating system to use that file’s area for new files. It’s similar to taking a cassette tape or a rewritable CD and moving it from the “Don’t Touch” stack to the “Okay To Record Over” stack. The stuff is still there until it’s actually recorded over.

“Undelete” worked so long as no areas containing bits of the file had been reused for another file.

It’s sort of like deleting the George Washington Bridge by taking down the exit signs pointing to it. The bridge is still there, but drivers can’t find it any more. Putting the signs back up “restores” the bridge, so long as the bridge and approach roads have not been torn up.

According to the story in the Times, this program appears to be far more intelligent than “Undelete,” able to perform what is almost a forensic examination of a drive or storage device.

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