- Now that we've updated our catalog cache size,
it's time to move on to our catalog settings
and more specifically, our XMP data.
So let me show you what I'm going to do now.
The next setting that I want to point out
is a setting found in the catelog settings
from our Lightroom menu.
So you're going to start at Lightroom Classic
and then you're going to scroll down to Catalog Settings.
And then we're going to make sure
that we have selected metadata.
Now, in this area, there is an option
to automatically write changes to the XMP.
So what is an XMP file?
When you're dealing with raw images,
those images are protected,
meaning they are unable to be modified
because the data in the actual picture
is protected and you cannot change it.
So what Lightroom does instead
is they create a sidecar file,
which has the exact same name
as your original image
but it has a .XMP at the end of it.
And within this small sidecar file
are a note log of all of the changes
that have been made to your image.
For example, if you turned your image black and white,
and you removed all of the saturation from your image,
that step or that command would not be found
in the raw file itself
and instead, that command would be found in the XMP file.
So if you go ahead and uncheck this,
you do get a warning
because any of the changes that you make in Lightroom
while this is unchecked
will not be written to the XMP.
But if you go ahead and check it, they will.
Immediately after every single thing
that you change in your develop module,
that little change is going to be written to your XMP.
And as you can imagine,
that's going to bog down Lightroom.
So if you are an advanced user
and you want Lightroom to run a little bit faster,
you can go ahead and uncheck this.
But if you are a beginner user,
my suggestion to you is to keep this checked.
So as you can see over here in my Finder window,
which has the files
that I'm working at currently in Lightroom,
if I go ahead and zoom in,
you can see that I do have the actual raw file,
which says cr2
but then there is a sidecar file,
which has the exact same name
and it has an xmp under it.
So these two files should always be together
and that's how Lightroom knows
that this is the original image
and this is where all the changes reside
that are being applied to the original image.