Author: Tim Grey

Today’s Question: For Lightroom Classic, would it be OK to just back up the catalog and not the previews? My previews take forever to back up.

Tim’s Quick Answer: Yes, it is perfectly safe to exclude the previews from a catalog backup for Lightroom Classic. In fact, the built-in backup feature that I recommend using automatically excludes previews from the backup.

More Detail: I strongly recommend backing up your Lightroom Classic catalog to help ensure you are safeguarding the information about your photos. Obviously, you should also be backing up the photos themselves as part of your overall backup workflow.

There is no need to back up the previews that are included in the folder along with the actual Lightroom Classic catalog, because those previews can easily be re-built later should you need to recover from a backup of your catalog.

Even if you are backing up your Lightroom Classic catalog using other software, I still recommend using the built-in backup feature to back up the catalog on a somewhat regular basis. That is because the built-in backup includes options to check the catalog for errors and to optimize the catalog. I recommend making sure both checkboxes for these features are turned on in the dialog that appears when a catalog backup is initiated.

Today’s Question: Can you use the same Lightroom Classic catalog on both an Apple computer and a Windows computer? I’m thinking of switching to a Mac laptop, but am concerned that once I convert to a Mac I’ll never be able to use Lightroom on a Windows desktop again. If you put the files and the catalog on an external hard drive, can you access it from both computers?

Tim’s Quick Answer: Yes, you can use the same Lightroom Catalog on computers running either the Windows or Macintosh operating system.

More Detail: The Lightroom Classic catalog file format is the same for both Windows and Macintosh, so you can switch a catalog between both operating systems without any problems.

The only thing you need to do is make sure the Lightroom Classic catalog is on a hard drive that can be written to by both operating systems. The default file system for hard drives on Windows is NTFS (New Technology File System) and the default for Macintosh is APFS (Apple File System). While it is possible to write to hard drives with either file system on both operating systems, this typically requires special software or drivers.

I recommend simply using a file system that is compatible with both operating systems. More specifically, I recommend using the ExFAT (Extensible File Allocation Table) file system.

If you store your Lightroom Classic catalog as well as your photos on an external hard drive that is formatted with the ExFAT file system, you can switch between working on a Windows or Macintosh computer by simply connecting the external hard drive to the computer and opening the Lightroom Classic catalog from that external hard drive.

Today’s Question: You have talked about moving files from one drive to another within Lightroom Classic. However, let’s say I installed a new drive and want to copy the files to the new one, but want to keep them on the old one as well. How do you do that in Lightroom Classic?

Tim’s Quick Answer: In this case I would use the “Export as Catalog” command to streamline the process of copying photos while still maintaining a link to those photos in the new location.

More Detail: The “Export as Catalog” command in Lightroom Classic enables you to export copies of your photos while creating a new catalog for those photos at the same time. In this case the creation of a new catalog probably isn’t necessary, but it does help ensure that the photos are referenced in the correct location without losing any of the information about your photos.

To get started, open Lightroom Classic and make sure the new drive you want to copy the photos to is connected and available. Then select the “All Photographs” collection in the Catalog section of the left panel in the Library module. From the menu choose Edit > Select None to make sure that no photos are selected. This will ensure you don’t accidentally export only part of the photos.

You can then choose File > Export as Catalog from the menu. Navigate to the location where you want to copy the photos, and specify a name for the overall library of photos, such as “My Photos”. Click the Export button and Lightroom Classic will export copies of all photos with the same folder structure as they were contained in on the source drive, with a new catalog created within that folder as well.

You can then launch the catalog from the new location by double-clicking on the file with the “.lrcat” filename extension. If you prefer you can also move the folder containing the catalog that was created as part of this export process to a different location, such as to your internal hard drive.

Today’s Question: In your GreyLearning Series on Optimizing Photos, in the lesson on HDR images you had a series of six captures ranging from a dark exposure to a light one. The sun was in the frame. My question is how did you make six captures with different settings without the sun moving, or apparently moving?

Tim’s Quick Answer: The key when including the sun (or moon) in the frame when capturing a series of exposures for a high dynamic range (HDR) result is to capture those exposures quickly using automatic exposure bracketing (AEB).

More Detail: While the sun and moon don’t seem to be moving all that fast across the sky to the unaided eye, they are certainly moving. In the case of the sun the rate of movement is about fifteen degrees per hour. That still isn’t incredibly fast movement across the sky, but it does create a risk that if you capture bracketed exposures that include the sun or moon, there could be a change in position for the sun or moon from one frame to the next.

Automatic exposure bracketing enables you to capture the various exposures as quickly as possible, minimizing the risk of movement between frames.

The specifics of how you employ automatic exposure bracketing will vary from one camera to the next, and not all cameras support this feature. In general, you will enable the bracketing via menu settings, where you can set the number of exposures to bracket and the number of stops between exposures. Two stops of separation between exposures works well for HDR bracketing.

With many cameras in addition to configuring the bracketing settings you’ll need to use a timer for the bracketing to be completely automatic. For example, you might set a 3-second timer so that when you trigger the exposure the bracketed captures will all be taken in rapid succession.

And, of course, to some extent HDR software can manage minor variations from one frame to the next.

For those interested, the HDR image in question was a sunrise photo of an abandoned homestead farmhouse in the Palouse region of eastern Washington State. You can see the photo on my Instagram feed here:

https://www.instagram.com/p/36alRoJ-fH/

Today’s Question: In the past you have recommended GoodSync for backing up photos. Recently you have been discussing BackBlaze. I’m trying to understand if you use both (and if so, how) or if BackBlaze has replaced GoodSync in your workflow.

Tim’s Quick Answer: I use both GoodSync (http://timgrey.me/greybackup) and Backblaze (https://timgrey.me/onlinebackup), with GoodSync providing my local backup and Backblaze providing my offsite backup.

More Detail: A good workflow for backing up your photos and other important data obviously involves making an additional copy of that data. Ideally, a copy of your data is also stored at a separate physical location, so that if there were a serious issue at your primary location, you still have a backup copy that can be recovered.

My primary tool for backing up my photos is a software application called GoodSync (http://timgrey.me/greybackup). I define jobs for each of my hard drives and use GoodSync to back up my primary drive to two backup drives. So, for example, I backup my Photos drive to both a “Photos Backup 1” drive and a “Photos Backup 2” drive.

I don’t happen to have a convenient way to keep one of my backup drives at a separate physical location, and so I use Backblaze (https://timgrey.me/onlinebackup) as an online backup solution that enables me to have a backup stored somewhere else.

Another advantage of an online backup is that it is relatively easy to maintain when I’m traveling, provided I have access to a relatively fast internet connection. Backblaze simply runs in the background, updating my online backup based on new or updated files on my computer.

This hybrid approach gives me greater confidence that no matter what causes me to lose photos or other data, I should be able to recover from one of my backups.

Today’s Question: With newer AI software [for enlarging photos], such as Topaz Gigapixel or the Enhancement feature in Photoshop, do these allow for a larger image to be printed without pixelation?

Tim’s Quick Answer: These latest tools do help to some extent, but they won’t dramatically improve the potential output size of an image. Rather, I see these tools as ways to produce enlargements with greater quality but not necessarily much larger than would otherwise be possible.

More Detail: Enlarging a digital image involves increasing the total number of pixels in the image, which means that new pixels need to be created and given specific color and tonal values.

As I’ve said before, with an image of good quality you can generally enlarge to a size that is twice as tall and wide (four times the image area) with very good results. As long as the viewer won’t get too close to the image, you can print significantly larger.

Some newer software such as Gigapixel AI from Topaz Labs and the Raw Details and Super Resolution features of Camera Raw from Adobe improve upon the previous technology for image enlargement, in part through the use of artificial intelligence and machine learning.

These technologies certainly offer an improvement over earlier tools, but they don’t suddenly provide a magical way to dramatically enlarge a photo. Rather, I see these tools as helping to improve the quality of a reasonable enlargement rather than enabling much more significant enlargement than is possible with other software.

Ultimately, the best output quality results from a high-quality image with adequate resolution for the intended output size. Some enlargement can be done without seriously degrading image quality, but there are limits to how large an image can be enlarged while still looking good from a relatively close distance.

Today’s Question: If you lower your screen resolution below its native resolution, does that not affect accuracy when assessing image sharpness at 100% view?

Tim’s Quick Answer: Yes, in terms of the image generally not appearing as sharp as it otherwise would. It is best to evaluate sharpness and apply sharpening at a 100% scale with the display set to native resolution, but with experience you can use different settings without difficulty.

More Detail: LCD displays have a fixed number of pixels, which limits their ability to adjust overall display resolution without impacting quality. Therefore, it is generally best to use the native display resolution for an LCD monitor.

As noted in a previous Ask Tim Grey eNewsletter, using a lower resolution on a display can provide a benefit in terms of making text larger and easier to read. However, this can also lead to lower display quality.

For very high-resolution displays this often isn’t a problem, because the smaller pixel size enables better quality when scaling the display. For example, a 13-inch Apple Retina laptop display has a resolution of 2560×1600 pixels. However, the standard display setting actually mimics a resolution of 1440×900 pixels.

So, if you’re using a display with a very high resolution, it is generally less of an issue to use a lower resolution than the native value. However, anytime an LCD display is set to something other than the non-native resolution there is some risk that the display will not appear as sharp, which can make it a little more difficult to properly evaluate sharpening settings for a photo.

That said, when evaluating sharpening settings, the focus is really more about the size of the effect relative to the size of texture transitions in the image, so I wouldn’t consider this a major issue. If you are more comfortable with your display set to a lower than native resolution, you can still apply sharpening very effectively.

Today’s Question: How do you know if you’re in 8-bit or 16-bit per channel bit depth?

Tim’s Quick Answer: Depending on the software you’re using, you may be able to determine the bit depth of an existing image or specify the bit depth used when creating a new image. You can also infer the bit depth of an image to some extent based on the file type.

More Detail: The first step in knowing what bit depth you’re currently working in for an image is to consider the type of file you’re working with. For example, a JPEG image will always be in the 8-bit per channel mode, because JPEG images don’t support bit depths higher than 8-bit per channel.

For a raw capture you can generally think of the image as being capable of 16-bits per channel, though in reality the source data is likely lower than that. Many cameras produce images with an analog-to-digital conversion of 12-bit or 14-bit per channel, with a relatively small number of cameras supporting 16-bit conversion. However, most imaging software only supports 8-bit and 16-bit per channel as the primary bit depth settings, so raw captures would typically be processed at 16-bit per channel even if you don’t have a camera that truly records 16-bit data.

Other file formats, such as TIFF and Photoshop PSD files, will vary since they support multiple bit depth settings.

The software you’re using may enable you to view the current bit depth. For example, in Photoshop you can go to the Image menu and choose Mode, then view which bit depth option is selected with a checkmark icon to the left of it on the menu.

In software such as Adobe Camera Raw, when processing a raw capture, you can specify the bit depth you want to use, which for a raw capture would generally be 16-bits per channel. Similarly, when exporting an image from Lightroom Classic you can specify a bit depth. The available options will depend on the file format being used, and how that file will be used, but the point is you can specify a bit depth for the image being exported.

Ultimately whether you’re able to easily determine the actual bit depth of an image depends on the software you’re using. Some software makes it easy to determine the bit depth, and others don’t provide that information at all. The key is to ensure that your workflow is structured such that you are making full use of the available bit depth for an image. For example, be sure to set the bit depth to 16-bit per channel when processing a raw capture in Adobe Camera Raw, and be sure the bit depth is set to 16-bits per channel on the External Editing tab of the Preferences dialog in Lightroom Classic for photos being sent to Photoshop.

Today’s Question: Is there anything that can be done to reduce the possibility of an image becoming pixelated when resizing?

Tim’s Quick Answer: The key to avoiding a pixelated image in general is to ensure you have adequate resolution for the intended output size. That means ideally starting with an image of adequate resolution, not enlarging too significantly, or ensuring viewers will not get too close to the final enlargement.

More Detail: A pixelated image is one where the resolution is not adequate to provide smooth edges, with an appearance that leaves the impression you can see individual pixels in the photo. An image that appears pixelated is generally the result of inadequate resolution, or a poor enlargement technique. Whenever possible it is best to start with an image that provides adequate resolution for the final output size.

For example, a 24-megapixel camera such as the Sony A7 III (https://bhpho.to/3scI7Rc) provides enough resolution to print up to about 13″x19″ without increasing the number of pixels in the photo (assuming no cropping of the original image). A 50-megapixel camera such as the Canon EOS 5DS R (https://bhpho.to/3CHXuGe) can print up to about 20″x30″ without enlargement.

If you used a camera with relatively low resolution or cropped the image significantly, the print size without enlargement will of course be smaller. And the more you need to enlarge an image for the intended output, the greater the risk of visible pixelization in the image.

To be sure, software has improved significantly over the years in terms of being able to enlarge a photo while retaining very good quality. But even with the best software there are limits.

As a general rule of thumb, an image of good quality can be enlarged to about double the width and height (four times the total image area) while maintaining good image quality. Beyond that, there is a risk that pixelization may become apparent.

Of course, this can be mitigated by viewing distance. If the viewer will be far enough away from the print, there is no limit to how significantly you can enlarge the image. A good example is roadside billboards, which look great from the highway but generally look rather pixelated when viewed up close.

So, try to be sure you are always starting with an image of adequate resolution, try to avoid the temptation to enlarge an image too significantly, and when a significant enlargement is necessary try to make sure viewers can’t get too close, so they won’t be able to see any pixelation in the image.