Let's talk about the fundamentals of how light room works behind the scenes. That will give you a much better idea of what's happening when we get into the more intermediate and advanced features as well when you install light room. Part of that process creates what's known as your light room catalog file, and you can't have light room running without having this catalog file open. And so you could say light room is a catalogue. Well, where is your catalog file? Because it's located somewhere on your hard drive, and it's a very important file, so you should know where it is. Well, if you're on a Mac, you can go to the light room menu at the top your menu bar and choose catalog settings. If you're on Windows, the same choice will be found under the edit menu instead, and that will bring up this screen. It'll tell you the location of your light room catalog file, and there's a show button. If you click that it will actually navigate you on your computer's operating system and show you th...
e contents of that folder, and I suggest you do that so you just get comfortable with what's there. Then, when you add images to your light room catalog file, you do that by importing. And when you import all that's happening is it's creating new records. Inside that light room catalog file, you get one new record for each image you import, and if you look at the contents of these, here's what it stores. First, it writes down the file name of an image you're importing. Then it also notes where precisely on your hard drive that image is located. It also sees if there was any camera generated information that it could grab, and that would be things like the shutter speed that was used, the aperture setting the camera model in the lens that was used. That's known as metadata in its stores that in the catalog file as well. And then finally, it makes a preview image of the file you're importing. And the preview image is about the same size as your computer screen, which is usually significantly smaller than the original file. At least if it was an original from a digital camera, then if you go into light room and you go to the develop module where you can adjust your picture, brighten it up. Maybe in this case, make it look more warm and get more shadow detail out of it. Well, all of those changes you made are saved in your light room catalog file, and they're saved is just simple text. So if I move the contrast up on the image, it will write down the word contrast in whatever setting it ended up at. And that's all it's doing for all the development settings that you apply. Not only that, though it then takes that lower resolution preview image and updates it to reflect those changes. Then, if you want to give that image to somebody else, you've got to think about it. You can go up to the file menu and choose export or choose export with preset. If you set up a preset and when you do, you have your original picture that is unchanged on your hard drive. Light room only stored the changes that you made in the light room catalog file, so when you tell it you want to export that image, it looks into that like room catalog file and says, Hey, are there any development settings there? And if it finds any, it then applies them not to the original picture, but only to that picture that you exported. So you end up with a resulting picture that looks exactly like it did in light room, but the original picture is unchanged. Those changes are just stored in the light room catalog file. And this is the same thing. If you go and print the image or say you want to edit it in Photoshop or do anything else that needs access to that final image Now, when you do export, you need that original picture file available. You need to have the hard drive that contains it attached to your computer, otherwise it won't be able to export. So Light room, in essence, is a non destructive editing program. You have a bunch of original files, which is what's representing the left side of my screen. Those could be raw files, Photoshop files, tiff files, J pegs, whatever file format light room supports. And then you have your light room catalog folder. In there, you have one file that ends with the letters L. Our cat, and that is where it keeps track of all the adjustment settings. You've made all those pictures because it does not change the originals in any way. Then in the same folder as that light room catalog file, there's a second file called previews dot L R data. That is where it saves all of those screen sized preview images. And that's what allows you to browse your images and view them and show slide shows. Even when the hard drive that contains your original images is not actively attached to your computer, then some people will have a third file, and it will be called smart previews. That file, if you have it, can allow you to not only look at your images when the hard drive that contains the originals is not attached, but it can also allow you to adjust your pictures. We'll talk about that in more detail later, but you have to go out of your way a little bit to get those to be created. They're not going to be created automatically for you. And so that's the way light room works behind the scenes. It's a nondestructive editor, and that's a great way to work because all the changes you're making are saved only a simple text inside that light room catalog file, and that makes it so. The file size is so little compared to working in Photoshop, so those are light room fundamentals. Next, we're going to cover round tripping. Round tripping is when you send an image from light room Photoshop and then have it appear in light room again when you're done.