Safe to Delete Previews

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Today’s Question: My computer has been sending me urgent distress signals, telling me that I need to free up hard drive space ASAP. My Lightroom previews.lrdata file is 58GB and contains only standard previews. My photos reside on an external HD. Can I safely delete the previews file to free up space on my computer? What would you recommend?

Tim’s Quick Answer: Yes, it is safe to delete the Lightroom Classic previews file. However, this will slow performance in Lightroom Classic, and over time the previews file will grow as new previews are built for your photos.

More Detail: Lightroom Classic builds lower-resolution JPEG previews of your original captures to speed up the process of browsing your photos. Those previews are stored in a previews file, which has the same base filename as your Lightroom Classic catalog file, with “Previews” appended to that name and a filename extension of “lrdata”. It is safe to delete this file if you need to recover hard drive space, as the previews can always be re-built later.

Deleting the previews file can certainly free up considerable storage space. Of course, this would generally be a temporary fix, since the next time you launch Lightroom Classic, previews will be built again for images in each folder (or other location) that you actually browse. Therefore, even if you need to delete the previews file temporarily, I would also look for other files that can be deleted in order to free up more hard drive space.

Later, once you have adequate storage space, you could build previews for all images in your catalog. To do so, first navigate to the All Photographs collection in the Catalog section of the left panel in the Library module. Then make sure there are no filters set so that you’re actually browsing all images, and then choose Edit > Select All from the menu to select all of the photos. Finally, from the menu, select Library > Previews > Build Standard-Sized Previews.

Another option would be to move the entire folder containing your Lightroom Classic catalog and related files to an external hard drive, in order to free up space on your internal hard drive. Keep in mind, however, that having the catalog on an external hard drive will degrade performance in Lightroom Classic, so it is best to keep the catalog on the internal hard drive of your computer if at all possible.

Virtual Copy to Master Photo

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Today’s Question: I have had occasion to make a virtual copy of a photo and like it much better than the original version I processed. I would like to keep the virtual copy as the master and delete the original. How can that be done?

Tim’s Quick Answer: You can indeed apply the adjustment settings for a virtual copy in Lightroom Classic to the master image, which effectively swaps the adjustment settings between these two versions of the photo.

More Detail: A virtual copy in Lightroom Classic represents an additional interpretation of a source photo. In other words, by using virtual copies you can have more than one set of adjustments applied to the same source image.

From time to time you may find that you are happier with the adjustments applied to the virtual copy, and so you want to retain that version as your master image, and perhaps discard the “other” version of the image.

Let’s assume, for example, that you have optimized your master photo in Lightroom Classic as a color interpretation of the photo. You then create a virtual copy and apply adjustments that produce a black and white interpretation of the image. You then decide that you want to keep the black and white version of the image, and discard the color interpretation. In other words, you want to apply the settings from the virtual copy to the master image.

To do so, you can simply select the virtual copy that you want to “upgrade” to having the status as your master image. Then go to the menu and choose Photo > Set Copy as Master. This will swap the adjustment settings for the photo, so that in this example the master image will have the black and white adjustments and the virtual copy will have the color adjustments.

At that point, if you only want to retain the primary version of your photo, you could right-click on the virtual copy and choose the option to Remove Photo. Just be sure that in this type of situation you are only ever removing a virtual copy, not removing the master image.

File Size Shrinks in Photoshop

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Today’s Question: Some years ago I scanned a 35mm slide. Lightroom [Classic] shows me the file size to be 108MB, and when I send the image to Photoshop I get the same size in the Image Size dialog. I have re-scanned the slide, and when I send it to Photoshop to prepare a JPEG image for submission to an agency, the file size shows as 54MB. What is causing the difference?

Tim’s Quick Answer: In this case the difference is the bit depth. The first image was set to a bit depth of 16-bits per channel, with the second image set to 8-bits per channel.

More Detail: The Image Size dialog in Photoshop provides what appears to be a file size value to the right of the Pixel Dimensions heading, but this value will not necessarily match the actual size of the file on your hard drive. However, the bit depth setting for the image will impact this size value, just as it will impact the actual size of the file when saved.

The file size shown in the Image Size dialog in Photoshop can be thought of as the estimated size of the image file if it is saved as a TIFF file with no layers and with no compression applied. Saving with a different file format or settings will result in a file size that differs from what is shown in the Image Size dialog.

However, the file size estimate does take into account bit depth. In this case both source images were likely scanned at a bit depth of 16-bits per channel, although it is possible the second image was scanned at 8-bits per channel. It is also possible, however, that the image had been converted to a JPEG image before the size was viewed in the Image Size dialog. JPEG images do not support 16-bits per channel, so that conversion would necessarily involve converting the image to 8-bits per channel. That, in turn, would cut the file size in half.

Again, the file size estimate in the Image Size dialog in Photoshop should only be viewed as an estimate based on pixel dimensions and bit depth, without reflecting the file format and related settings for the final saved image file.

Lightroom Classic versus Camera Raw

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Today’s Question: Friday you recommended using Lightroom Classic instead of Adobe Camera Raw for basic image adjustments. What makes Lightroom Classic better than Camera Raw?

Tim’s Quick Answer: In the context of optimizing raw captures, Lightroom Classic and Camera Raw are essentially the same thing. The advantage of Lightroom Classic in the context of my answer last week was simply related to image management, not optimization.

More Detail: My suggestion to use Lightroom Classic to apply adjustments to the raw capture was simply related to a workflow that involves managing photos with Lightroom Classic. You will achieve exactly the same results processing a raw capture using Adobe Camera Raw or the Develop module in Lightroom Classic.

The reason I was recommending Lightroom Classic “instead of” Camera Raw in my answer was that the answer was predicated on using Lightroom Classic to manage photos. If you’re going to send a photo to Photoshop for further optimization, it is necessary (or at least highly recommended) that you send the photo from Lightroom Classic to Photoshop, rather than opening the image directly from Photoshop.

When you send a photo from Lightroom Classic to Photoshop, the raw processing is being conducted by Lightroom Classic, with a finished image sent to Photoshop. That finished image will be saved as a TIFF or PSD file, depending on the setting you have established in Preferences in Lightroom Classic.

In other words, if you’re using Lightroom Classic to manage your photos, you won’t really be able to use Camera Raw for processing the raw capture, since that will be handled by Lightroom Classic instead. Therefore, it is advantageous to apply at least the basic adjustments in Lightroom Classic before sending the image to Camera Raw.

But for photographers who are using Photoshop to optimize their photos, and are not using Lightroom Classic at all, there is no benefit to Lightroom Classic in terms of raw processing. Both Camera Raw and Lightroom Classic’s Develop module provide the same results. They simply involve a slightly workflow.

Cleaning Camera Viewfinder

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Today’s Question: On my ancient Canon 50D I recently have accumulated significant artifacts in the viewfinder when I set up for a photo. Fortunately, the artifacts do not appear in any photos, which I think eliminates the sensor as the culprit. But I have thoroughly cleaned the viewfinder and the mirror (as well as my lenses), but they are still appearing and are very distracting. What am I missing in my cleaning chore?

Tim’s Quick Answer: It sounds like you are missing the focusing screen. While it may be possible to clean the focusing screen on many cameras, that focusing screen can be quite delicate, so you may want to opt for replacing the screen (http://timgrey.me/screen).

More Detail: Cleaning the optical viewfinder on a camera can be relatively straightforward, but doing so won’t always provide a completely clean view. I recommend using a cotton swab with lens cleaner solution to clean the eyepiece of the viewfinder.

Beyond that, you may want to have your camera professionally serviced if the view through the viewfinder shows obstructions that are distracting.

Cleaning the mirror yourself can be a little risky, as the mirror and related components are very delicate. I recommend only using an air blower to clean debris off the mirror, with the camera titled so the debris will fall out of the camera rather than remaining inside. Cleaning the mirror with a cotton swab and lens cleaner involves the risk you will use too much pressure and damage the mirror or other components.

If the viewfinder eyepiece and mirror are clean but you’re still seeing debris through the viewfinder, the focusing screen is the most likely culprit. With some cameras (including the Canon 50D) the focusing screen can be replaced. This is often the best solution, as the screen is rather delicate and can be damaged with cleaning. There is a special tool that enables you to safely handle the focusing screen, and this tool is generally included with a replacement screen.

You can get information about a replacement focusing screen (in this case for some Canon cameras including the 50D) here:

http://timgrey.me/screen

Hiding Noise

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Today’s Question: To reduce noise in a photo, do you ever reduce Black levels?

Tim’s Quick Answer: Yes, in some cases I will darken the shadows in an image to help hide noise, provided I am actually happy with the degree of contrast involved with such an adjustment.

More Detail: Noise will generally be more prevalent in dark areas of an image, because those areas contain less information. In effect, noise is the opposite of information in the context of a photo. Bright areas have more information, and therefore less noise.

When you’re not able to adequately reduce the appearance of noise using noise reduction adjustments, you can help hide that noise by darkening up the darker areas of the image. That could mean darkening up the black value for the image, or darkening shadows in general.

Of course, I don’t want to exaggerate contrast or make an image appear too dark just to hide the noise. So I would only want to take this approach for an image where I intended to darken up the shadows regardless of the noise.

In other words, the motivation is often reversed here. I don’t generally decide to darken the shadows in an image to hide the noise, but rather feel a sense of relief when my intended darkening of the shadow areas also helps hide any noise that appears in those areas.

This is particularly an issue for luminance noise. Generally speaking, you can achieve great results reducing color noise for most images. Luminance noise can be a particular challenge, because reducing that luminance noise will have the side effect of reducing texture and detail, causing a loss of sharpness in the photo.

Minimal Use of Lightroom

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Today’s Question: I use Photoshop, and not Lightroom Classic at all. But I might like to use just the catalog features in Lightroom to simply organize and keep track of my files and updates. Can that be done?

Tim’s Quick Answer: Yes, you could most certainly make use of Lightroom Classic to manage your photos, and primarily use Photoshop to optimize your photos. However, I would suggest at least applying basic adjustments in the Develop module in Lightroom, to take the place of Adobe Camera Raw in the context of a Photoshop-only workflow.

More Detail: Many photographers make use of Lightroom Classic exclusively to organize, optimize, and share their photos, without the use of any other software. And, of course, many photographers make use of Photoshop, without using Lightroom Classic in their workflow. It is, however, most certainly possible to make use of both Lightroom Classic and Photoshop in a blended workflow.

In my view Lightroom Classic certainly provides some organizational advantages, primarily because of the catalog that is at the core of a Lightroom-based workflow. Among other things, the catalog enables you to quickly and easily search for photos across your entire catalog based on a wide variety of criteria.

You could absolutely make use of Lightroom Classic primarily for organizing your photos, and still use Photoshop as a primary tool for optimizing your photos. You would simply send a photo to Photoshop from Lightroom Classic when you want to optimize that photo in Photoshop.

However, as a Photoshop user who is not making use of Lightroom Classic, you would be familiar with the use of Adobe Camera Raw to apply initial adjustments to raw captures before continuing the process of optimizing the photo in Photoshop. When you send a raw capture from Lightroom Classic to Photoshop, you will not have the opportunity to use Camera Raw to process the raw capture. Instead, you would want to make use of the Develop module in Lightroom Classic for that purpose.

So, you could use Lightroom Classic (primarily the Library module) to organize your photos and use the Develop module within Lightroom Classic to apply at least the basic adjustments to the raw capture. You can then send an image to Photoshop to apply any and all finishing adjustments there. When you save and close the new image file (TIFF or PSD) created as part of this workflow, that derivative image will appear alongside the source image within your Lightroom Classic catalog.

Of course, over time you may find that you appreciate some of the other features available in Lightroom Classic. That includes the Map module to manage photos based on location metadata, as well as a variety of options for sharing your photos in a variety of ways. But you can most certainly put Photoshop to use as a key tool for optimizing your photos, even when using Lightroom Classic for managing your photos.

Resolution Anomaly

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Today’s Question: Magazines are asking for images at 300 ppi resolution, even for images that will only be presented online. Doesn’t this mean I’m providing “wasted” resolution? Also, when I’ve resized images and displayed them alongside each other in Photoshop, sized to fit the screen, the higher resolution image (at about 30% zoom) appears less sharp than the lower resolution image (at nearly 100% zoom). What is going on here?

Tim’s Quick Answer: The pixel per inch (ppi) resolution is essentially meaningless for images that will be displayed digitally. Also, the closer an image is sized to a 100% scale on a display, the sharper that image will generally appear.

More Detail: A reference to “300 ppi” for an image suggests that the intent is for the image to be printed. While optimal resolution settings vary based on the specific output, 300 ppi is a common setting for printing. For an image that will be displayed digitally (such as online or in a digital slideshow), all that matters are the pixel dimensions, which should be set to match the intended presentation size.

Of course, you could still describe the pixel dimensions for an image that will be shared digitally using a pixel per inch value. For example, you could specify that the image needs to be sized at 6 inches on the long side at a resolution of 300 pixels per inch. But it is much simpler to just say that the image should be 1,800 pixels on the long side.

Regarding the image with larger pixel dimensions not appearing as sharp or detailed as the image with smaller dimensions, this relates to the scaling of the image on the display.

An image will look its best in terms of sharpness at a 100% view, referred to as the Actual Pixels view in Photoshop. This is why it is recommended that you view an image at 100% scale when evaluating settings for sharpening a photo.

With the scenario described in today’s question, the higher resolution image is being scaled down to fit within the display area, which causes a loss of perceived sharpness in the image. If you viewed both images at 100% scale, they would both appear equally sharp, though you would obviously be seeing a smaller portion of the image that has larger pixel dimensions.

Photoshop does a good job of scaling the preview for images, but viewing at a 100% scale still provides an advantage in terms of sharpness. Just because an image has larger pixel dimensions does not mean that image will appear with better quality than an image with smaller pixel dimensions. What matters most is that the pixel dimensions are optimal for the intended output.

What that translates to when sizing images for a digital display is that it is best to resize the image to the exact pixel dimensions that will be used to present the image. For example, for a digital slideshow you would want to resize the image based on the resolution of the digital projector to be used.

Comments Not Supported

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Today’s Question: I am wondering what the Comments section under the Library module in Lightroom Classic is meant for. This Comments section always shows “Comments not supported here”, so no entries can be done or edited, although this field remains always empty. Can you please clarify?

Tim’s Quick Answer: The Comments section at the bottom of the right panel in the Library module in Lightroom Classic enables you to view and add comments for images that have been published via one of the online Publish Services options. For example, you can view “likes” and comments, and add comments, for photos you have shared to Facebook directly from within Lightroom Classic.

More Detail: Many photographers like to share their images on social media sites and other online outlets. In my experience, however, I’ve found that many photographers are not aware that it is possible to share photos to a number of online services directly from within Lightroom Classic, using the Publish Services feature.

When you configure a service under Publish Services, that service behaves much like a collection in Lightroom Classic in terms of grouping photos together. The difference is that with a Publish Service you can publish images that have been added to that collection to the applicable online service.

For example, you can configure Facebook as a Publish Service. You can then add images to that Publish Service collection, and then publish the images. When you add a new image to the collection, you can publish again to add just that new image to the applicable service (such as Facebook in this example).

For images that have been published in this way, if the service in question supports comments, you can see (and add) comments via the Comments section at the bottom of the right panel in the Library module.

For example, Facebook supports both “likes” and comments. You can therefore see a count of likes for a given photo, as well as comments others have posted to the photo, within the Comments section. You can even add comments (or replies to other comments) in this section.

Of course, if you don’t use the Publish Services feature, then you won’t be able to make use of the Comments section. You could, however, add your own personal comments to metadata in one of the various fields intended for this type of purpose.

Sharpening for Focus

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Today’s Question: Regarding your advice on sharpening, I recently read that expecting/hoping to bring out-of-focus areas into sharp focus is fantasy. The article said sharpening only enhances areas that are in focus. Do you concur?

Tim’s Quick Answer: Yes, I would mostly agree with the overall concept here. Sharpening will not cause an out-of-focus image to appear to be entirely in focus. You can improve the perceived sharpness, including of out-of-focus areas, but that doesn’t not provide the same result as having the image in focus in the first place.

More Detail: I often describe sharpening as enhancing contrast where contrast already exists in an image. This creates the appearance of greater sharpness and detail in the image. You can also think of sharpening as reducing the size of gradations along contrast edges in an image.

Sharpening can dramatically improve the overall appearance of a photo, but there are limits to how much you can achieve with sharpening.

For example, sharpening can help compensate for a photo captured with a lens featuring slightly less resolution than another lens, since the loss of sharpness in this case would be minor.

If a photo is a little bit out of focus, sharpening can help make the image look less blurry, but that sharpening won’t result in an image that will look as good as it would have if the focus was established properly at the time of capture.

If an image is significantly out of focus, sharpening will enable you to change the appearance of the photo, but it certainly won’t produce a photo that appears to have been in focus in the first place.

Similarly, there are techniques for reducing the appearance of motion blur in a photo. But even more than with a photo that is out of focus, with a photo that exhibits motion blur you can’t use a filter to magically get the photo to look like there wasn’t any motion blur. You can get an improvement, but not a perfect result.

So, sharpening can help make up for an image that was captured with less than perfect focus. But if the image clearly has the appearance of being out of focus, sharpening in post-processing is not going to provide a magical solution.