Using Smart Previews in Lightroom Classic

The video below demonstrates how to create Smart Previews in Lightroom Classic for Working with Offline files. https://youtu.be/OLNelp1Z-ok

Smart Previews are smaller versions of the original photo that Lightroom Classic can use when:

• Working with photographs in the Develop module (and Quick Develop panel) if the originals are offline (on a drive that’s not plugged in for example).
• Syncing files from Lightroom Classic to the cloud (to access using Lightroom on mobile devices).

Smart Previews are completely separate from the previews used in the Library module (in Grid, Loope, Zoom, Survey, and Compare views), and are stored in their own file (Smart Preview.lrdata”). 

To create Smart Previews, the original files must be on-line. Therefore, you will want to make the Smart Previews before taking the images off-line. There are several ways to create Smart Previews:

• On Import: in the File Handling panel, check the option to “Build Smart Previews”.
• In the Library module: select the photo(s) and select Library > Previews > Build Smart Previews.
• When exporting as a Catalog: select File > Export as Catalog and check the option to “Build Smart Previews”.

Lightroom Classic automatically creates Smart Previews for all photos in a collection that has sync enabled (to use with Lightroom on mobile devices) Lightroom syncs the Smart Previews to the cloud (not the originals) to save space and decrease the amount of data that needs to be transferred.

In the Develop module, the Histogram panel displays what type of file/preview is available:

• “Original” if there is not a Smart Preview built for the file and the original is on-line.
• “Original + Smart Preview” if there is a Smart Preview and the original is online.
• “Smart Preview” if there is a Smart Preview and the original is off-line.

Basically, the rule is that if there is an original, then Lightroom will use the original, if the originals are not on-line, then Lightroom will use the Smart Preview.

• If you make changes to a file that is off-line and has a Smart Preview, when the originals become available (comes back on-line), any changes there were made to the Smart Preview are automatically applied to the original. There is no action that you need to do – Lightroom automatically applies all changes made to the Smart Preview to the original file. 
• Note: if the original file is online, both the original and the Smart Preview are both updated as changes are made.

Keep in mind that these smart previews are smaller version of the original files. With that said, since they are only 2540 pixels on the long edge, when applying Sharpening and Noise Reduction settings in the Details panel, the Smart Preview view at 100% will be a different magnification than the original. Therefore, for the most accuracy, you might need to confirm the setting when the files are on-line and you are able to view the original at 100%. 

Smart Previews can also be used if the original files are offline in the following situations however, for the highest quality, you’ll most likely want your original files when outputting files.

• Sharing files via the Publish Services panel.
• Exporting as JPEGs.
• Creating a book layout (although you will not be able to print the book until the original images are on-line as the quality of the Smart Previews will not be high enough to print).
• Creating and outputting a video slideshow (although they can not be used to output a slideshow to PDF because of quality concerns).
• Creating and exporting web galleries.

---