All processing done by Lightroom in the Develop module is always done with the 1:1 previews, except for the cropping operations. You have the choice of when Lightroom will generate the 1:1 previews, either before you will need them or when you will need the 1:1 previews. You have read my article Lightroom: Slow As Molasses Or Lightning Fast? where I mention that Lightroom has to build it’s previews on the fly if they don’t already exist. This will make Lightroom and your computer very, very slooow. But you didn’t generate the 1:1 previews during the import.

How can I generate the 1:1 previews after importing my photos? You have changed your mind after reading my settings on previews:

  1. Select the images you want to generate previews for in the Grid View or select all of your photos in the Grid View
  2. Library menu -> Previews -> Render 1:1 Previews
  3. Depending on the number of 1:1 previews you will be generating, this can be a very, very long process. The length of time will depend on the CPUs. If you plan on generating previews for thousands of photos, this should be an overnight job or even a week-end job.

Lightroom: Render Previews

Lightroom: Render Previews



Lightroom:  Generate Previews

Lightroom: Generate Previews

This is a balance between the speed of Lightroom and the amount of disk space used for the previews.

In my humble opinion, speed wins over disk space. Disk space has become so cheap, you can buy a 1 Terabyte external USB hard drive for around $100 Canadian.