Sometimes I experience that a image files date/time on the file system differ from the image metadata/EXIF info.
I use this command to extract the date information available in the file

$ exiftool -time:all -a -G0:1 -s filename.jpg

The output from the command can be like

[File:System]   FileModifyDate                  : 2016:06:08 14:40:24+02:00
[File:System]   FileAccessDate                  : 2016:09:01 23:39:40+02:00
[File:System]   FileInodeChangeDate             : 2016:09:01 23:39:17+02:00
[EXIF:GPS]      GPSDateStamp                    : 2015:07:28
[EXIF:GPS]      GPSTimeStamp                    : 14:46:47
[EXIF:IFD0]     ModifyDate                      : 2015:07:28 16:47:09
[EXIF:ExifIFD]  CreateDate                      : 2015:07:28 16:47:09
[EXIF:ExifIFD]  SubSecTime                      : 426
[EXIF:ExifIFD]  DateTimeOriginal                : 2015:07:28 16:47:09
[EXIF:ExifIFD]  SubSecTimeDigitized             : 426
[EXIF:ExifIFD]  SubSecTimeOriginal              : 426
[Composite]     GPSDateTime                     : 2015:07:28 14:46:47Z
[Composite]     SubSecCreateDate                : 2015:07:28 16:47:09.426
[Composite]     SubSecDateTimeOriginal          : 2015:07:28 16:47:09.426
[Composite]     SubSecModifyDate                : 2015:07:28 16:47:09.426

This can give a lot of info about the original date/time of the file.
We can now decide to modify a files FileModifyDate with the info from DateTimeOriginal

$ exiftool "-filemodifydate<datetimeoriginal" filename.jpg

Source: http://www.sno.phy.queensu.ca/~phil/exiftool/faq.html#Q24