ExifTool is the one to go for.
It has a time shift feature that allows you to shift the dates.
Date/Time Shift Feature
Have you ever forgotten to set the date/time on your digital camera
before taking a bunch of pictures? ExifTool has a time shift feature
that makes it easy to apply a batch fix to the timestamps of the
images (ie. change the "Date Picture Taken" reported by Windows
Explorer). Say for example that your camera clock was reset to
2000:01:01 00:00:00 when you put in a new battery at
2005:11:03 10:48:00. Then all of the pictures you took subsequently
have timestamps that are wrong by 5 years, 10 months, 2 days, 10 hours
and 48 minutes. To fix this, put all of the images in the same
directory ("DIR") and run exiftool:
exiftool "-DateTimeOriginal+=5:10:2 10:48:0" DIR
The example above changes only the DateTimeOriginal tag, but any
writable date or time tag can be shifted, and multiple tags may be
written with a single command line. Commonly, in JPEG images, the
DateTimeOriginal, CreateDate and ModifyDate values must all be
changed. For convenience, a shortcut tag called AllDates has been
defined to represent these three tags. So, for example, if you forgot
to set your camera clock back 1 hour at the end of daylight savings
time in the fall, you can fix the images with:
exiftool -AllDates-=1 DIR
See Image::ExifTool::Shift.pl (download in PDF format) for
details about the syntax of the time shift string.
Some things to note:
Test on a small batch of copies first until you get the date syntax you want.
I suggest you copy or move your images to a new folder first.
And run the command on that directory.
If you run exiftool on a directory it will look in sub directories and modify any image files it finds.
Exiftool WILL automatically append '_original' on the end of your original files and create a new copy for you with the modifications.
You can override this by using the '-overwrite_original' option.
exiftool -overwrite_original -AllDates+="0:2:1 10:48:0" /Users/UserName/Desktop/testFolder
This example shifts forward 0 years, 2 months, 1 day, 10 hours, 48 minutes, 0 seconds.
Using a single set of time shifts i.e instead of "0:2:1 10:48:0" you use "10:48:0".
Exiftool will see this as hh:mm:ss.
And you can omit 0 where you do not want to put a shift.
exiftool -overwrite_original AllDates+="9::" /Users/UserName/Desktop/testFolder
This example shifts forward 9 hours.
exiftool -overwrite_original -AllDates-="9::" /Users/UserName/Desktop/testFolder
This example shifts back 9 hours.
Notice AllDates-=" and AllDates+=" , one has a plus one has a minus.
Also Remember you are shifting time not stamping a time stamp.
So if my original date was :
2011:07:21 01:41:29
and I used exiftool -overwrite_original -AllDates-="24::" /Users/UserName/Desktop/testFolder
Then I would get : 2011:07:20 01:41:29
Do download the PDF with the syntax
And make sure you look at the difference with the options -overwrite_original_in_place and -overwrite_original
Documentation
Best Answer
"Primary Platform" is part of the ICC profile, which is related to colorspace. Under "Device Model" and "Colorspace", you should see sRGB, which was created jointly by Microsoft and Hewlett-Packard (HP). If you look further you should also see the color profile is listed as being created by, and copyrighted to, HP.
It appears that somewhere along the line, the color profile is being added to the image. It's not clear if this is on iOS (which I've seen claims stating it is not color-managed), during the move to Mac or in iPhoto/Photos. I have images that were in iPhoto and copied back out, and have not been touched by Photos, that have the same Exif data. I have also used the Photo Investigator app on iPhone to view Exif data for images that were taken on iPhone but have not yet been transferred to a computer, and they list the Color Model as RGB, not sRGB, so it would appear the profile is added later.