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[♪ Music playing ♪] Hi and welcome. My name's Julieanne Kost
and we're going to take the next few minutes to look at all of the enhancements
that were made to the DNG file format in Lightroom 4.
Now most of you are probably familiar with DNG,
and it's most often associated with saving raw files,
but what's really important about DNG and what differentiates it
from the other file formats like Nikon's NEF and Canon's CRW file format
is that the DNG file format is openly documented and openly licensed,
so it is not a proprietary file format--which for me, it gives me confidence
as a photographer that I will be able to open up my photographs far into the future,
because any software developer or manufacturer
will be able to read and write these DNG files.
Of course there is additional benefits as well. For example, the file size is
going to be a lot smaller when you convert to raw to DNG even though we don't
throw anything away. We maintain everything that's in the original file
in the DNG file format. It can greatly simplify a workflow,
especially if you've got a multiuser environment or an educational setting
where you have multiple people using different cameras, they can convert to DNG,
and that will simplify what software is needed to read those files.
And lastly and probably most importantly is versioning, right?
So versioning is built into the file format, so as new technologies come about
or as technologies evolve, we can include those in this file format.
So let's go ahead and take a look at all these improvements in Lightroom 4.
I'll go ahead and select just maybe these first 4 images here in Lightroom,
and then I'll go under the library menu to show you the options
when converting photos to DNG. Now, right now I'm starting in the library,
but if I was importing files, I could import and convert to DNG,
and I would get this same option. And the option that I'm talking about
is the Embed Fast Load Data. So what is that?
What that allows us to do is, when we create the DNG files,
we're embedding a little bit of information--maybe like 200 K, so it's not much--
we're embedding that information into the DNG.
And what it gives us is a preview file. Now, you might be thinking
of the preview files that are in the library module. This is not what I'm talking about.
Those cached previews that are in the library module,
Lightroom will still continue to make those so that when you're viewing images
in the library, you'll be able to see things quickly.
But what customers actually request more often is a speedier experience
in the develop module. So by saving, or embedding, this fast-load data
into your DNG files, they can load up to eight times faster in the develop module
so that is fantastic. And this is on by default.
There is a preference, you can turn it off, but I really don't know
why you wouldn't want to take advantage of that.
Now the second new feature, also very interesting, is right underneath
the Embed Fast Load Data, and that is to Use Lossy Compression.
So this is kind of a paradigm shift for some people,
because most of us think that our DNG files are our archival,
kind of our digital negatives, right? Well we now have the ability
to use lossy compression on these files to make them a lot smaller.
This is not for everyone, and this is probably not to be used
on every image that you shoot. But let's take some examples
maybe where--I don't know--maybe you go on safari and you take 5000 images.
Well, you might know that you're never ever ever going to want 4000 of those images.
Instead of having those images be full-sized DNG files taking up a lot of space
on your hard drive, you could use this lossy compression
in order to reduce those file sizes. But I'll tell you, it is lossy.
It's like JPEG compression. If you want to know more about it,
you can read it in the developer's kit. But we are going to take that information
and throw away a bunch of it. So this is not what you want to do for that hero shot.
This is only all of your outtake shots. Or maybe you photographed a wedding,
and you've got 500 images that are great and 1500 that are not.
Maybe those 1500 you know that they're never going to see the light of day,
but you don't want to throw them away. That would be a great candidate
to use this lossy compression. One caveat, of course, is that if you do use
the lossy compression and then you have to use that image in the future
and you really need to push it, like you really need to bump up the highlights
or it's very under or overexposed, making huge changes to this file,
well because it's saved with compression, it would tend to break down
earlier than, say, an image that was not saved with that lossy compression.
The third enhancement to DNG takes this process--this compression process--
one step further. Now, it's not available on import, and it's not available
in that convert dialogue that we just saw.
But it is available on export. So you'll see here if I choose to export my files
as DNG, not only can I use the lossy compression, but if that is enabled,
I can actually change the pixel dimensions of my image.
So unlike import and convert files where all we're doing is compressing the file,
this actually will throw away total pixel count.
So I could say maybe if we go back to that wedding example,
if you had those 1500 images that you knew were never going to be printed
maybe larger than 4 by 6, you could go ahead and resize those to fit, as well.
And obviously this is going to make your file size much, much smaller
than just using the lossy compression alone.
Again, it's not for everyone, it's not for every shoot,
and I realize that hard drive space is relatively inexpensive, so some people
are going to choose to never use this, but I want to make sure that you know
that the opportunity is there if it's something that makes sense for your workflow.
And one last thing that I just want to mention--
I will cancel out of here--and that is when you start saving in your DNG files with
maybe this lossy compression versus the DNG files that don't have lossy compression,
you'll notice underneath the Metadata panel here in the library module in grid view
I can now change this to file type, and you'll see that the digital negative--
if we just close that there--you can see that it says that the ones that I have saved
are lossless. I haven't saved any in the other format when I'm actually
reducing the image size, but if I do, then that will come up as another option here.
Excellent. Thank you so much for watching.
My name's Julieanne Kost. I hope to see you again soon.
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