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Adobe Lightroom Classic Lightroom Preview (.lrprev) Files.

About Lightroom Lightroom Preview (.lrprev) Files.

Product:  Adobe Lightroom Classic  |   Subject: Adobe Photoshop Lightroom Classic

In this exercise, we will learn about Adobe Lightroom Classic Lightroom Preview (.lrprev) Files.

In this section, I want to show you what Lightroom does when it generates the previews. I think this is a lot of fun. Now, this is not important information to make use of Lightroom. But for me being the tech geek that I am, I like learning about how the nitty-gritty of everything fits together. Maybe this might help you. So what I'm doing right now is I've created a collection that I'm preparing for my next course. And what I'm doing beforehand is to generate all of the previews at a one-to-one ratio. Now all of these images here, or at least most of them, are raw files. 


You can see that by just clicking on here. 

As Adobe Photoshop Lightroom is building, all the previews go through every single raw file within that collection. It's generating that preview file. Now you can see the counter going very, very slowly. 

So it takes a few seconds for every single image file to generate its appropriate one-to-one file. Now, why is this important? Well, for me, I like working with one-to-one previews, especially with the images. When I'm going to work with the develop module, I want to make sure that I can see all of those details when making my adjustments. So, that's why I like to create all of the one-to-one previews beforehand before I do any work; otherwise, my workflow is interrupted. 

Sometimes, you know, even those two seconds, it adds up when you get 100 images, 500 images, or even 1000 images. It's because of that I wanted to show you, at least for me, how very important it is to have all these things rendered beforehand before you start to do work. So my workflow is after I finished a photo shoot, I'll go down to my computer, I'll transfer all the image files, I'll import them into Lightroom. I will let Lightroom render one-to-one image previews before I do any work. So sometimes it may mean I'm away from my computer for an hour, maybe two hours, even longer, depending on the number of photos that I have to render at one to one. Now, my computer is pretty fast. I'm just going to minimize this and show you a few details. Now on this window, you can see that this is the master catalog that I was working on within Lightroom. All the previews are stored in this folder called Master previews.lr data.


Now I want to show you the preview data's size, even though it's only one-third complete. So I've gone ahead and brought this up here. You can see that already, I've generated 85,000 files, and it's already 8.6 gigabytes of files. 

So as you render one-to-one previews of more images, the disk's size for the preview data will get bigger and bigger and bigger. This window is just my search window to show you what's happening on my file system. You can see that these are individually rendered preview files. 

They're about two and a half megabytes, three megabytes. In some cases, they're even a little bit bigger than that. Every image that is being rendered from a raw file at a one-to-one ratio will end up being pretty big. That's why you have such a huge space out here. This window I want to show you is something that I think is interestingYou can see from this window here that I have an i5 processor. 

Now, this is a 2500 K, so it's about five, six years old. It's running at 3.3 gigahertz. You can see the spikes in the CPU usage. Every single one of these spikes is the rendering of that preview file. It's a nice, neat pattern to see how the CPU functions when Lightroom uses it when Lightroom is doing all of the work behind the scenes. 

So for me, Lightroom being what it is, is a fantastic software application because I can get to doing what it is that I love to do, which is adjusting my photos, retouching my photos, and ensuring that my photos stand out and pop out. You know what, create that emotion that I want for the viewer. But before I can do all of that, I have to make sure that my computer does all the heavy lifting to render all the things that I need and have them all ready before I get to work. So let's go back to Lightroom and show you what that looks like. And you can see once again, it's still building all of these previews, and it hasn't actually gone that much further. 

In fact, I believe with three to four seconds per image; it will take quite a bit of time to create all the one-to-one previews. So right now, I'm going to stop there and take a break. And I'll be back in about an hour or so. And I'll be ready to edit all of the photos that I have here within this collection. 

I hope this section has helped you understand just the inner workings of how Adobe Photoshop Lightroom does its magic. 

It's kind of neat how everything is all put together. The key thing that I want to emphasize is Lightroom is about speed. I like to work fast to ensure that I can go shooting some more and work with more clients to do more things that I want to do faster. But to do that, you have to have that kind of computing power behind your software application. In my case, even though I have an i5 processor from 456 years ago, it's still doing a pretty good job. 

The only limitations that I have right now are the speed, the speed at which Lightroom reads from the disk. And even though I've set up my disk systems in a raid zero array, sometimes it's still not as fast as I'd like it. So this is how you can speed up your workflow:

  • You can pre-render all of your files that you need to beforehand,
  • You can have SSD disk drives that'll ensure that Lightroom reads all of those preview files quickly. 
  • And of course, you can have a much, much faster processor

All of this, of course, adds to more money. So once again, I do hope this has been helpful just to give you a whole idea about the inner workings of Lightroom. To me, this is a lot of fun.