Ask Tim Grey

Today’s Question: I have about one hundred photos in a Lightroom Classic catalog on one computer, and I want to move all the images into my main Lightroom Classic catalog on another computer. How can I go about this without losing any of my work?

Tim’s Quick Answer: Assuming these are two separate catalogs with no duplication in terms of the images involved, you can simply merge the smaller catalog into your main catalog using the “Import from Another Catalog” command.

More Detail: The first step in merging catalogs across two computers is to get the catalog and photos that you want to merge into your primary catalog available on the computer where that primary catalog is stored. If you had already been working with the smaller catalog and the related photos on an external hard drive, you can simply connect that external hard drive to your primary computer. Otherwise, you’ll need to transfer the files, which can be done with the help of the “Export as Catalog” command.

Start by going to the “All Photographs” collection in the Catalog section of the left panel in the Library module. Select the “None” option on the Library filter bar so all images are shown and then choose Edit > None from the menu so no image is selected. Then go to the menu and choose File > Export as Catalog. In the “Export as Catalog” dialog navigate to an external hard drive that has enough space for both the catalog and photos. In the “Save As” field enter a meaningful name. Make sure the “Export negative files” checkbox is turned on, so photos will be copied along with the catalog. I also recommend turning on the “Include available previews” checkbox. Click the “Export Catalog” button to initiate the process.

Once the export is complete, connect the external hard drive to the primary computer, and open your primary catalog in Lightroom Classic. Then go to the menu and choose File > Import from Another Catalog. Navigate to the folder on the external hard drive that contains the exported catalog, select the catalog (it has a filename extension of .lrcat), and click the Choose button. Make sure the “All Folders” checkbox is turned on so all images will be imported. From the File Handling popup choose “Add new photos to catalog without moving”. Click the Import button to start the merge.

Since this process will have imported the images where they are, they’ll appear under a separate heading for the external hard drive in the Folders section of the left panel in the Library module. You can then drag the applicable folders to the top-level storage location for your primary storage that contains all your other images, so all photos will be consolidated.

By following this process, you’ll have consolidated your photos into a single catalog, while preserving absolutely all the work you had done in the second catalog.

Today’s Question: I have about 220,000 images in my Lightroom Classic catalog. The previews file is getting quite large at over 1.1 TB. I’ve tried removing 1:1 previews but that did not decrease the size much. In a recent video you mentioned having over 400,000 images. How do you manage the size of the previews file?

Tim’s Quick Answer: You can manage the size of the previews file in Lightroom Classic by not building 1:1 previews if you don’t need them, configuring the preview settings so they don’t consume as much space, discarding previews for images you aren’t as likely to browse, and even discarding all previews and starting over with different settings and a more selective approach.

More Detail: The previews file associated with the catalog in Lightroom Classic contains standard (approximately display size) and 1:1 (full resolution) preview images for the photos in your catalog. This serves as a cache that improves performance when browsing your photos, but the previews file can also consumer considerable storage space.

First off, one thing to keep in mind is that it is possible to simply delete the Previews file (it has the same base filename as the catalog but with “Previews” appended to the name, and with a filename extension of .lrdata). Doing so will quickly free up considerable hard drive space, but of course it also means your browsing experience will be slower because previews will need to be built on the fly as you browse images for the first time. But this can be a great way to do a bit of a reset, especially if you have the time to let Lightroom Classic build previews for your most important photos.

Also, you can configure the previews so they consume less space. Changing the settings combined with discarding the previews enables you to clear up the space and then not consume as much space moving forward. In the Catalog Settings dialog you can specify how long 1:1 previews are preserved. On the Previews tab you can set the “Automatically Discard 1:1 Previews” popup to “After One Day” or “After One Week”, rather than the default of “After 30 Days”. Note that 1:1 previews are only needed when you zoom into an image, but not in the Develop module where the preview is based on the source image rather than the previews cache.

You can also adjust the size and quality for standard previews in the Catalog Settings dialog. I recommend choosing the size option from the “Standard Preview Size” popup that is closest to the horizontal pixel dimension for your monitor display. This is based on the setting you’re using in your operating system, not the physical resolution of your display. For example, if you’re using a 4K display set to 1920×1080 resolution, I recommend using the “2048 pixels” option rather than Auto, as the latter would cause larger previews than are necessary to be built. You can also choose Low rather than Medium from the “Preview Quality” popup if you want to further reduce the space required for previews at the expense of preview quality.

In addition to the above, you can choose to discard previews for selected photos. This could be helpful if, for example, you store key photos on one hard drive and less important photos on another drive. You could select all photos on the less important drive and from the menu choose Library > Previews, then select “Discard 1:1 Previews” if you only want to discard the larger 1:1 previews, or “Discard Standard and 1:1 Previews (which is a relatively new command) if you want to discard all previews for the selected images.

Note that if you have discarded all previews, for example, you can then select photos you want to be able to browse more quickly, and then build previews for them by choosing Library > Previews > Build Standard Previews from the menu. This process can take a bit of time depending on how many photos you’ve selected, but after that process is complete your browsing experience will be much faster for the photos you’ve built previews for.

Today’s Question: As a follow-up to your answer about color spaces, if the limiting factor is the image bit depth, why not just use a higher bit depth?

Tim’s Quick Answer: To truly leverage a higher bit depth to achieve the benefits of a larger range of colors, you would need to start with higher bit depth in the original capture. In other words, until and unless cameras offer higher bit depth at the sensor level, there’s little benefit to working in a higher bit depth.

More Detail: When optimizing photos, in many respects you are limited by the quality of the data you started with, which in the context of digital photography means the quality of the original image capture. For example, one of the reasons I strongly advocate for the use of raw capture rather than JPEG capture is to avoid the image quality degradation caused by lossy JPEG compression.

As noted in yesterday’s answer, bit depth determines how many possible color values an image can contain. For example, and 8-bit per channel image can contain almost 16.8 million colors, while a 16-bit per channel image can contain more than 281 trillion possible color values.

However, converting an 8-bit per channel image to 16-bit per channel won’t change the number of colors actually present in the image. Applying adjustments may increase the total number of colors represented, but doing so will never get you to the same point you would have been had you started with high-bit data to begin with.

Similarly, today’s cameras primarily process image data at 12-bit, 14-bit, or in a relatively small number of cases 16-bit per channel. Therefore, converting a raw capture to 32-bit per channel won’t provide any significant benefit in terms of expanding the existing data in the image. In addition, doubling the bit depth will double the base file size.

Furthermore, there isn’t much support for bit depths above 16-bit per channel in most imaging software. When 32-bit per channel is supported, such as in Photoshop, it is primarily focused on enabling the editing of high dynamic range (HDR) images, and many of the editing features are not supported above 16-bit per channel.

Today’s Question: You’ve talked about choosing a color space for editing our photos, but why do we need to choose a color space in the first place? Couldn’t we all just use a single space that includes all colors?

Tim’s Quick Answer: Because the number of colors available in an image is limited by the bit depth of the image, it can be advantageous to choose a color space that is well-suited to how an image will ultimately be shared.

More Detail: A color space defines the range of colors that will be available in an image. It would therefore be reasonable to assume we could just use a color space that includes the entire range of the visible spectrum, so that any color capable of being seen with normal human vision would be available for our images.

However, images are limited in the total number of colors they can contain, based on the bit depth of the image. For example, 8-bit per channel images can contain almost 16.8 million colors, and 16-bit per channel images can contain more than 281 trillion colors. So, particularly for 8-bit per channel images, it can be important to choose a color space carefully, especially if strong adjustments might be applied to an image.

Because of these issues, color spaces have been created with specific purposes in mind. For example, the sRGB color space was created to encompass the range of colors that could be displayed on a typical monitor based on the available hardware at the time. However, for various types of print output a different color space makes sense because of the different colors that can be reproduced with different types of printers and print media.

It is also important to keep in mind that simply choosing the largest available color space is often not a good idea. For example, the ProPhoto RGB color space is huge, going beyond the visible spectrum, which makes it sound like a great choice. However, with such a large color space it is very easy to create posterization (the loss of smooth gradations) in an image with strong adjustments on an 8-bit per channel image.

If you’re working with 16-bit per channel images, it is relatively safe to always work in a very large color space such as ProPhoto RGB. However, for 8-bit per channel images I recommend opting for a smaller color space such as sRGB or Adobe RGB.

Today’s Question: I’ve been getting a popup window telling me that an Adobe application (it doesn’t tell me which one) is not genuine and will be disabled if I don’t buy a license. But I have a Creative Cloud subscription! How can this issue be resolved?

Tim’s Quick Answer: If one or more of the Adobe applications you have installed gets flagged as non-genuine when you do have a valid Creative Cloud subscription, you can use the Creative Cloud Cleaner tool to resolve the issue.

More Detail: Full disclosure: today’s question was not from a reader, but from myself! I ran into a (very frustrating) experience last week where several of the Adobe applications I have installed were flagged as non-genuine, and I got repeated threats that the applications would be disabled soon.

A button in the alert leads to a page offering you the opportunity to buy Adobe software, but without any real information on how to resolve the issue when the software you have installed is genuine.

So, I spent (wasted) some time in a chat with Adobe customer support. They were able to provide a list of which applications were considered non-genuine on my computer. As you can imagine, the applications in question had been installed using Adobe’s Creative Cloud application, through the account that I pay for that includes the full suite of Adobe applications.

Despite having installed the applications in the usual (and legitimate) way, they were somehow flagged as being non-genuine. Customer support was not able to provide any information on how the applications could have been flagged when they were legitimate.

While customer support was able to provide a solution, that solution involved using their Creative Cloud Cleaner tool, which requires uninstalling all Adobe Creative Cloud applications. That meant I then had to spend (waste) considerable time installing multiple Adobe applications again.

The only saving grace was that I did not lose my preferences or other settings as part of this process. But I don’t appreciate the inconvenience when I’ve only used Adobe’s Creative Cloud application to install legitimate applications as part of a subscription that I pay for (no, I don’t get a free Creative Cloud account from Adobe).

It is obviously frustrating to have had to put the time into resolving this issue. It is also frustrating that customer support couldn’t provide any information on what might have caused this issue. So, if any Adobe employees reading this know what happened, I’d love to know so I can perhaps make sure this issue is never repeated in the future!

Today’s Question: Regarding the Whites and Blacks adjustments in Lightroom Classic, is there any need to use the clipping preview option you mentioned when adjusting an image that has very low contrast?

Tim’s Quick Answer: As long as it is clear from the image preview or histogram that there is no risk of clipping the highlights or shadows, there’s no need to use the clipping preview feature while applying adjustments. However, I still recommend at least reviewing the clipping preview to confirm none is present.

More Detail: If an image is properly exposed and of relatively low contrast, and you don’t intend to adjust the image to exhibit strong contrast, there may not be any real benefit to using the clipping preview feature. However, I do recommend at least a quick check just to be sure there isn’t any clipping in the image.

For a somewhat typical image, it is common to want the brightest pixels to be white (or nearly so) and to want the darkest pixels to be black (or nearly so). Using the clipping preview, such as by holding the Alt/Option key while adjusting the sliders for the basic tonal adjustments, enables you to ensure you aren’t introducing problematic clipping with your adjustments.

With a low-contrast image there is much less risk of clipping, and so it would be reasonable to not use the clipping preview feature for those images. I still prefer, however, to at least quickly check for any clipping by holding the Alt/Option key while dragging the slider for Whites and Blacks.

Ultimately, with a low-contrast image that doesn’t have any risk of clipping based on the intended adjustments, it is perfectly reasonable to apply those adjustments based solely on a visual evaluation of the image, without using the clipping preview feature.

Today’s Question: I just watched a video where the presenter adjusts the Highlights and Shadows first and then sets the white & black points. I typically do this in the opposite order. Does it really make a difference if you set the black & white points before (or after) the Highlights and Shadow settings?

Tim’s Quick Answer: Ultimately, all that really matters is what the final settings are for the adjustments. However, in my view it is best to establish the maximum and minimum tonal values with Whites and Blacks first, and to then refine the level of apparent detail using the Highlights and Shadows sliders.

More Detail: Because the Whites and Blacks adjustments determine the overall limits of tonality for an image, I recommend establishing the value for those adjustments first. I will refine the setting for Exposure as needed before adjusting the value for Whites and Blacks, but I definitely recommend refining the Highlights and Shadows adjustments after adjusting Whites and Blacks. These same concepts, by the way, apply equally to Lightroom Classic, Lightroom, Camera Raw, and any other software that uses similar adjustments.

All the tonal adjustments have a degree of overlap between them, so that for example if you’ve set the value for Whites and Blacks and then modified one of the other adjustments, you may have created clipping of highlights or shadows in the image. This is one of the reasons I recommend using the clipping preview option, accessible by holding the Alt/Option key while adjusting the sliders for these tonal adjustments.

My approach is to first establish a setting for the Exposure slider based on a visual evaluation of the image. Then set the white and black point with the Whites and Blacks sliders, holding the Alt/Option key as part of that process to check for clipping preview.

At that point I’ll generally reduce the value for Highlights to enhance perceived detail and contrast in the relatively bright areas of the image. If you instead increase the value for Highlights, be sure to either use the clipping preview when doing so, or to adjust the Whites value using clipping preview to confirm an appropriate setting.

I then adjust the Shadows slider, leveraging the clipping preview option if using a negative value, to evaluate clipping of the relatively dark areas of the image. If there is too much clipping as a result, increasing the value for the Blacks slider can provide a solution.

You can most certainly refine these adjustments in any order you prefer. I find the above workflow to be helpful, but the most important thing is to make use of clipping preview as part of the process to ensure you’re applying adjustments based on clear information about the impact on the image.

Today’s Question: I renamed my Lightroom Classic catalog and associated files using the Rename Catalog command as you suggested. Is there any reason to keep the previous catalogs and files from when Lightroom automatically renamed with upgrades? I assume catalog backups made prior to renaming can be deleted?

Tim’s Quick Answer: As long as you are sure that the catalog files in question are from older versions of Lightroom Classic or are backup copies, deleting those files won’t cause any problems for your current catalog.

More Detail: While Adobe has made helpful changes to Lightroom Classic in terms of how catalog updates are handled, many photographers still have accumulated copies of outdated catalog files, as well as old backup copies of catalogs.

As long as you’re certain of which files relate to the current catalog, and that any unrelated files are not needed, it is safe to delete those files not associated you’re your current catalog. For example, the earlier versions of the current catalog that were from earlier versions of Lightroom Classic don’t need to be retained. In addition, numerous backup copies of your current catalog (or of prior catalogs) don’t need to be retained.

I do, however, recommend keeping a few catalog backups from various times, just so you have something to fall back on in case you run into an issue of corruption with your current catalog that might also have affected a recent backup. Obviously, the older a catalog backup is the less helpful it would be to recover from, since there may be many photos and updates that aren’t reflected in that older catalog backup.

Note, by the way, that one of the things I highly recommend doing to help minimize the harm that would be caused by a lost or corrupted catalog is to make sure the “Automatically write changes into XMP” checkbox is turned on, which can be found on the Metadata tab of the Catalog Settings dialog in Lightroom Classic.

Today’s Question: I was missing some photos in Lightroom Classic and used “show in finder” and located them. How do I get them into Lightroom Classic??

Tim’s Quick Answer: If the photos have a missing status, you’ll want to reconnect the missing images with the source files. If the photos are not in Lightroom Classic at all, you can use the Synchronize Folder command to import the photos that aren’t present.

More Detail: The “Show in Finder” command (“Show in Explorer” on Windows) enables you to display a window showing the storage location for a photo in your Lightroom Classic catalog.

For example, if some photos in a folder are missing, you could right-click on a photo that is not missing and choose “Show in Finder/Explorer” from the popup menu to go to the folder location where the missing photos are expected. The missing photos may have been renamed on the hard drive, for example, or they may have been moved to a subfolder, among other possibilities.

If you’re able to locate the source file for a missing photo in this way, you can reconnect the photos in Lightroom Classic. Start by clicking on the exclamation point (!) icon at the top-right of the thumbnail for the image to bring up a dialog where you can click the Locate button. In the dialog that appears, navigate to the folder location and select the applicable source image, then click the Choose button. The image in Lightroom Classic will be updated to reflect the correct filename and folder location for the image.

If, on the other hand, your exploration led you to discover that some images in the folder on the hard drive are not in your Lightroom Classic catalog, you can use the Synchronize Folder command. Right-click on the folder in the Folders section of the left panel in the Library module in Lightroom Classic and choose “Synchronize Folder”.

In the dialog that appears, turn on the “Import new photos” checkbox, which will have an indication of the number of photos that were found to the right of the label. I also recommend turning on the “Show import dialog before importing” checkbox so you can configure the settings you want to use for adding the photos to the catalog. Turn off the “Remove missing photos from catalog” and “Scan for metadata updates” checkboxes. Click OK, and the photos that were not in the catalog will be added.