Re: Corrupt JPG Files

On Wed, 11 Apr 2007 16:05:45 -0400, ASAAR <caught@xxxxxx> wrote:

That may be true for windows, but I'd be surprised if all
applications are similarly fooled. Many times I've tried to view
image files (jpg, gif, etc.) using Irfanview and will see a message
stating that the file extension is incorrect and with an offer to
correctly rename the file.

Any image viewer/editor that I've ever seen would be fooled.
Virtually every file type contains header info that identifies the
file as a particular type. The reason that Irfanview and a number of
other programs give an "incorrect extension" message it that they read
the file extension and then compare it against the file's header
information. If the header info does not agree with the file's
extension and the program reading it is designed to identify specific
file types by header info, such as Irfanview, then it will identify
the true file type based on the information found in the file's
header.
If the header info was damaged, which can and does occur, then the
file will not be recognized as the correct file type, regardless of
its extension.
That type of identifier must be built into the program being used. It
is neither accidental nor coincidental.


--
jimbok
.

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