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- [Instructor] ExifTool is a free command line program

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that can read and modify embedded metadata

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and it runs on Windows, Mac OS and Linux.

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You can learn more about it

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and download the software @exiftool.org.

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It's most basic mode operation

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is to simply list all the metadata it can find in a file.

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Even though it's called ExifTool,

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it can read some other types of metadata

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from files that it knows about and supports.

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Usually though, we'll use it for media files of some type,

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images, audio or video.

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ExifTool is also a useful program if we're writing scripts

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or processing large amounts of files.

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We can use it to extract metadata

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from a bunch of files at once

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or to change values one at a time or in bulk.

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This makes it quite helpful

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in both information gathering workflows

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and file sanitization workflows.

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We can think of a variety of scenarios

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where this could be handy.

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Perhaps we're a photographer and want to set our copyright,

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license data and project number

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on each of 600 photos we took,

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or we might want to strip GPS data

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and camera serial number data

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from photos we're sending to an art competition

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or to share online.

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Many services strip sensitive metadata automatically now,

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but not all do,

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so it's good to know how to do that for ourselves

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and it's useful to know

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how to add metadata to images as well.

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Let's take a look at a photo I took a few years ago

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on a trip to Barcelona.

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This was taken inside the Mercat De Sant Antoni,

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pardon my pronunciation,

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and I know that I took this photo with my camera

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that doesn't have a built-in GPS feature.

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So I'd like to add some GPS metadata to this photo

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so it'll show the right location in my photo browser.

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Most photo browsers on most platforms

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let us do this within their interface,

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but they're all different.

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So let's use ExifTool,

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which works the same way across all platforms

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to explore this photo's metadata

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and to make the changes we need to.

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I'll switch over to my PowerShell terminal here.

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And I'll change to the directory where my photo is stored.

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Now let's explore the metadata for this file

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with a command exiftool

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and the name of the file.

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This gives us a huge amount of information

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from basic information about the file,

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like its name, its size, and so on,

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to more specific information

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like the camera model name,

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the software the camera was using,

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and details about the exposure time

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and other values that the camera wrote into the file.

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We can also read only specific values if we want to

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using their argument names.

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We can find the argument names that apply to a given file

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with the -args option.

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I'll recall my previous command and add that here,

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and I'll run it again.

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And here on the left of the specific arguments

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that correspond to each of these values.

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For example, we can get just the exposure time

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and F stop values for a photo like this.

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If these values have been written by the camera

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or other software,

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that's pretty useful

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if you're looking for specific information

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in a set of files.

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But we can also use argument names to set values too.

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I mentioned earlier

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that this file doesn't have GPS information.

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And if I move back to my photo browser

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and open the file info,

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I can see that there's no map presented.

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So let's add some GPS information

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with the arguments GPS latitude and GPS longitude.

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Those argument names don't appear in the list for this file

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because they're not set for this file,

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so that can be a little tricky.

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The manual pages for ExifTool on Linux and Mac OS

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or the ExifTool website

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if you don't have manual pages on your OS,

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provide a rich source of documentation

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and list the arguments available to us.

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To add my GPS information,

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I'll need those latitude and longitude values,

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so I'll pop over to the web

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and grab those from a mapping site.

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I'll search for the location that the photo was taken,

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and here in the URL

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I can find the latitude and longitude values

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that I'm looking for.

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I'll copy those values

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and I'll switch back to my terminal.

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Using those values, I'll populate two arguments.

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All right, exiftool -GPS latitude equals that first value

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- GPS longitude equals the second value,

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and then the name of my file.

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When I ran this command,

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ExifTool made a copy of the original

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and replaced it with my updated image.

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So, let's open that up and take a look at the GPS data.

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There's a location right where I expected it to be, great.

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Keep in mind though,

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we could have just as easily put in

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incorrect GPS information

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and make it seem as though this photo

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were taken at another market anywhere in the world.

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Removing metadata is just as important

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and we can remove specific values

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by setting their arguments to an empty string.

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For example, I could remove the GPS information I just added

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with exiftool -GPS latitude equals nothing

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- GPS longitude equals nothing, and the name of the file.

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Now when I open the file again,

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I can see that the GPS information is gone

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from this newly made copy.

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The information is still there in the previous copy

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so keeping the copy straight is important

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if you're redacting sensitive information.

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We can also use ExifTool to extract information from a file

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and represent it elsewhere.

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For example, I took this photo in 2018,

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but the creation date here in the file information

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says it was created today.

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That's because this actual file was created today

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when we changed the GPS information just a moment ago.

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So that's correct if you look at it one way,

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but it may be the case

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that I want to represent this file's creation date

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with the actual date that I took the photo,

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that's when the photo was created after all.

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To do that, I can use the less than symbol

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with a metadata argument

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to set the file's creation date like this.

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All right, exiftool "-filecreatedate<exif:createdate"

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and the name of the file.

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This has quotes around it,

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so the full argument is pass to ExifTool.

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This reads the X of create date

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into the file create date value.

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I'll press return.

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And if I switch back to my file browser,

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I can see that that value was updated

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from the date inside the embedded metadata.

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This date value is actually stored in the file system

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not the file itself,

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and we'll explore how that works in the next chapter.

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Files can have a lot of dates associated with them

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both internally in their embedded metadata

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and on the file system.

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The metadata dates vary by file type,

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but many photos

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will have a variety of creation and modification dates

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that can be interesting to explore.

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These embedded dates and the file system dates

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can be useful for different purposes,

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but some of them, especially file system dates,

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can be modified when files are copied or edited.

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For example, if you're undertaking a project

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to scan old family photos and documents,

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you might choose to leave the date you scan them

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as their regular file system creation date

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and store the date information

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from when the photos were actually taken

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in an embedded field,

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which is less likely to be altered

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when files are copied or edited.

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While ExifTool can be a little bit tricky to learn,

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it's an incredible piece of software

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and a valuable tool to become familiar with.

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I enjoy using it when I work across different platforms

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because it shows me the same information in the same place

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using the same commands syntax.

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It frees me from having to remember

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how to use different tools on different platforms.

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And keep in mind, it's not only for images.

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If you work with metadata,

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I encourage you to spend some time exploring it.