When determining the date to stamp the file with, DateMeNow first tries to find EXIF information associated with the file, and extract the date from it. If no EXIF information is found, DateMeNow will take the date when the file was last modified (which often coincides, or is very close to, the actual date when the picture was taken if it came from a digital camera), and use that date instead.
It can also optionally then add that last modified date as EXIF date taken for the image.
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