For a long time Lightroom users have been able to perform some work on their images even though the original image files were not available. That work was limited, however, to metadata in the Library Module. All other adjustments were impossible without access to the image files. The Quick Develop panel in the Library Module was greyed out and switching to the Develop Module didn't help. All of those adjustments were unavailable as well. Many of us keep our ever growing collection of images on one or more external drives. If your production computer is a laptop you face this issue whenever you take it with you and leave those drives in the studio. Lightroom 5 makes this a thing of the past with Smart Previews!
Smart Previews are an interesting middle ground between your images and your Catalog. They don't happen automatically. If you haven't built a Smart Preview for an image you still get the same results as in prior versions of Lightroom. For this discussion I created a simple Catalog with six images. Three are on the internal drive and three are on an external drive. If the external drive is unavailable we can still see the Previews in the catalog.
The expected indicators are there. The external drive is darkened and the folders have a question mark on them indicating that Lightroom can't locate the images. In the upper right corner of each missing image is the missing image icon. It has changed appearance a bit in Lightroom 5. Clicking on that indicator will present the missing file dialog asking if you'd like to locate the file.
Switch to the Develop Module and we can see that all the controls are greyed out and the message "Photo is missing" shows up at the bottom of the Histogram panel.
If you elected to build 1:1 previews you can still zoom in and look around but that's about it. So how do you educate your Previews and make them Smart? There are two main ways to do this.
Initially, you can elect to have Lightroom build Smart Previews during Import. On the destination side (the right side) of the Import Dialog you will see a new option to Build Smart Previews. Check the box and Smart Previews will be built for all the imported images.
If you didn't build them during Import then you can build them using the Library > Previews > Build Smart Preview option.
Notice that there is also a Discard Smart Previews option in the same menu. If all images are selected or no images are selected then Lightroom builds Smart Previews for all the images. If only one image is selected you are presented with a dialog.
Now when the external drive goes missing we see a different icon for images that have Smart Previews.
The Folders Panel still looks the same but now the image with the Smart Preview has a different icon. When selected you will see "Smart Preview" at the bottom of the Histogram Panel. Clicking on this icon gives us a different message that a mere missing file dialog.
Interesting! It tells us that the file can be edited using its Smart Preview. If we switch to the Develop Module we now can make all sorts of adjustments on the image even though the original image file is back at the studio! Neat!
Again we see "Smart Preview" at the bottom of the Histogram Panel and all of the adjustments are available.
OK. Great. But what happens when we get back to the studio and reconnect the external drive? Nothing short of magic! All of those adjustments are applied to the file as if it was there all along. You will notice that the icon disappears since the image file is not available. The indicator at the bottom of the Histogram Panel changes to "Original + Smart Preview" to remind us we have a Smart Preview built for this image.
When multiple images are selected Lightroom provides a handy summary at the bottom of the Histogram Panel. This changes depending on whether the external drive is available or not.
The four indicators are (from left to right):
- Originals without Smart Previews
- Originals + Smart Previews
- Smart Previews
Each is followed by the number of images in the selection that fit each category.
Is there a cost for this enhanced functionality? Yes. But not as much as if you kept the original files on your internal drive. In this simple six image Catalog the space required to store the original image files is 61.9 MB. The 1:1 Previews take up 12.9 MB. The Smart Previews for all six images only take up 1.2MB! That's only 1.94% the size of the original files! Now, your mileage may vary depending on the size of your individual image files but Lightroom 5 does make it possible to bring a significant amount of data with you allowing you to edit your images while you are away from the original files. Now that's SMART!