pachmars wrote: …Im not sure what is meant by metadata.
For a picture file, Data are the values of the pixels used to make the image. Metadata are information about the data, like where and when it was taken, focal length of the lens, shutter speed, title, caption, keywords, and so on. Such metadata is usually embedded in the picture file by the camera, and it transfers with the image to computers, phones, etc, and apps like Photos, Preview, Lightroom, and other image systems make some of this metadata available for you to examine. Photos has an Info Window that shows some of this metadata.
One of the cool things about the internet is that this sort of definition and Information is all available on Wikipedia, specifically, here:
Wikipedia Metadata
So, in what I said before, you can substitute "Date Taken" for "metadata," since that's the sort of metadata that you're interested in.
"Date Taken" is sometimes stripped from a picture by people so that they can't be traced, and sometimes you have to ask folks to include it. Photos from web pages, chats, and email may have the "Date Taken" stripped by the app that's used.
Again:
Nothing can be done if the images transferred from other people do not contain the correct dates.
So, in your example, if a picture taken on Dec 2 and upload on Dec 4 has the Dec 2 date stripped from the file, then there is no way to restore that date without talking to the people who took the picture, so that you
can change the date on a photo with "Adjust" in the Info Window for the picture.
