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In one of the previous movies, I mentioned that one of the reasons why people like the DNG format, is because it allows us to create a file which is compressed. Now there are two different types of compression that we can use with this format. By default the DNG compression that we use is called loss-less, in other words, it creates a smaller file size without losing any important information. Yet, we can also convert our files with what's called lossy compression. Now, this allows us to get rid of information, so that we can have a smaller file size. Now, why in the world would we want to have an image which gets rid of information, so we have a smaller file? Well, let's take a look at how we can do that.
And also how this works, and why we'd want to do that. By going through a scenario. The first thing I want to do here is navigate to this folder which is titled, Becky. Here I was standing at graduation, at the school where I teach, and I looked behind me and there was this smiling student. And as I scrolled through these images you can see that they're all pretty similar. Yet, let's say that I really like the first and third image but I'm not so sure about the second photograph, or maybe it's the first photograph that I don't like. Yet I'm not really willing to delete it or get rid of it. Well, rather than deleting it, you do have another option. What you can do is convert this file to a lossy DNG format. What that allows you to do, is to have all the speed and flexibility of working with the DNG file format without all the file size.
So before we actually start the conversion process, and talk about how that works. Let's take a look at these files in the finder work explorer window. Navigate to the thumbnails and then right click or control click. Here in this menu, select show in finder or show in explorer. The reason why I want to do this, is so that we can look at what files we actually have to work with. In this case we have these three files here. And they're all right about 18 megabytes. And again, one of the reasons why we might want to use lossy DNG is to have a much smaller file size.
Often, we'll do this with those photographs, which aren't our top selects. But we still want to hang on to them, rather than deleting them completely. Well here, what we can do is say, convert this image to what's called a lossy DNG. Let's look at that process. We'll go back to Light Room for a moment. In Light Room, we'll navigate to the library pull down menu. Then we'll choose the menu item, which is convert photo to DNG. Now we've seen this before. So again, library, convert photo to DNG. Click on that menu item. Here in this dialogue, we'll only convert our raw files. And for demo purposes, I'm going to keep the original. So we can compare these two files.
Then we'll use our lower case extension. Compatibility, we'll use the latest and greatest of Camera Raw. Medium size preview, embed fast load data. And now we want to turn on the check box here to use lossy compression. This will allow us to create a much smaller file. In order to do that, simply click OK. Yet when you click OK, what you really need to do is pay attention to what's happening. What's happening is it's converting this file, becky-1.dng, into a different file format.
Notice that it says becky-1-2. In other words, it's another iteration or another version of this file. In order to see this file, let's once again right click or control click on it. Then select show in finder on a Mac, or show in explorer in Windows. This will bring us back to this folder. Here I'll notice the new lossy DNG doesn't have a thumbnail, so it got rid of that. So it's a smaller file size because of that. It's also a smaller file size for other reasons as well, talk about that in a second.
But, take a look at this. What once was about 18 megs is now only about five. Now with one image that isn't that big of a deal, but let's say that you have those photographs that you captured which, really aren't the keepers, and you have a thousand of them, well you could then convert them to this format and have a much smaller file size. Again, typically you'd want to do this with those files which you aren't quite ready to throw away, but you also don't want the full high resolution version of the files. Well, let's then compare these two files in Light Room so that we can see or compare the differences between these two.
To do that, we'll navigate back to Light Room and click on the Becky folder. Now this folder, it's only showing us the new DNG, the lossy DNG file. To see both files, we need to synchronize the folder. You can synchronize or update a folder by right clicking or control clicking it. Then you simply choose synchronize folder. In doing that, it will say hey you know what. There's a image which isn't part of our like room catalog. OK, they found one photograph great. Let's go ahead and click synchronize. This will take us to import dialogue. What we can do here is we can choose to bring that file back, Becky-1. I'm going to bring that back in and add it to the library. And we'll click import.
Again, typically you won't need to do this. I'm just doing this so that we can have some fun and compare these two files. So here we have, Becky1-2 and then we have the original Becky-1 file. Remember, this one is huge, 18 megs, this one's about 5 megs. Well, if we click on the icon, which allows us to compare two files, we can compare the two, so that we have the smaller file here, and the larger file over here. Now we can zoom in on the images. I'll go ahead and zoom in here. What I want to do is zoom in, so that we can compare the detail that we have in these both photographs.
Keep in mind, 5 megs versus 18 megs. They look almost, identical. So what's the big deal? And what's the downside of working with this lossy format? Well, the file does look the same. The lossy DNG. I like to think of it as a file which is a little bit more, brittle. In other words, if we're going to bring these files over to the develop module and if we're going to recover highlights or add contrast or change exposure, well, we can't make as dramatic of adjustments because there isn't as much information there.
Again, the file is a little bit brittle. So just keep that in mind. While you are saving file size, you are losing a bit of flexibility. And that's where the tradeoff is. Of course, if it's a file which you aren't really certain that you're going to be using, perhaps it's worthwhile. Well, either way, at least now you know how you can convert your files to this particular format, which is called lossy DNG, and you know a little bit about that overall process, and how that works.
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