Posterization versus Resolution

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Today’s Question: Regarding image posterization in the Library module that does not appear in the Development module [in Lightroom], isn’t it possible the image may not have enough resolution to display at the magnification the user has set in the Library Module?

Tim’s Quick Answer: It is true that the preview image available in Lightroom may not have adequate resolution to present a good quality preview, especially when you zoom in on the photo. However, that would present a different visual effect than the posterization that can occur with the preview images in the Library module in Lightroom.

More Detail: The previews for your photos presented in Lightroom are created differently for the Library module versus the Develop module. In the Library module you are essentially viewing a JPEG preview for each image, while in the Develop module you are viewing a full-resolution preview based on the underlying image file and the adjustments you’ve applied in the Develop module. This is why, for example, when the source image files are not available (such as when you’ve disconnected an external hard drive) you can still view your photos in the Library module but not in the Develop module.

Because the Develop module is creating a real-time preview based on the underlying image file and the adjustments you’ve applied, the source image must be available to view the image in the Develop module. That also means you’ll see the most accurate (and highest quality) view of your image by viewing it in the Develop module.

In the Library module you are viewing a JPEG preview of your photo. In general that means the overall quality may not be as high as what you see in the Develop module. Among other things, that can cause a degree of posterization (loss of smooth gradations of tone and color) as noted in a previous edition of the Ask Tim Grey eNewsletter.

If the resolution is low (such as when zooming in on an image for which a 1:1 preview has not been generated yet) the quality will suffer, but not in a way that produces posterization. Instead, the image will take on something of a “jagged” appearance. For example, curved lines within the image will look rough rather than smooth, with more of a “stair-step” pattern than a smooth curve.

Both of these issues can obviously impact your perception of the overall image, especially when taking a close look as specific details in a photo. Therefore, it is always best to use the Develop module in Lightroom when you want to critically evaluate the quality and details of a photo.

Exposure Increments

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Today’s Question: My camera (Olympus OMD EM1) has settings for both 1/2 and 1/3 F-Stops. It also has settings for full (1 stop) and 1/3 ISO. What is the best combination of settings to use?

Tim’s Quick Answer: The decisions here primarily relate to a choice between more precise control over exposure versus a more streamlined workflow for adjusting exposure settings. Although I’m a self-confessed control freak, I prefer to use half-stop increments for exposure settings and full-stop increments for ISO.

More Detail: Let’s first consider the overall exposure settings, meaning the increments for setting the lens aperture (f-stop) and shutter speed. With most cameras you can choose between one-half stop increments and one-third stop increments.

Opting for one-third stop increments obviously provides you with greater precision in setting your exposure. I would argue that for most photographic situations, that precision doesn’t provide a significant advantage. After all, the incremental benefit in being able to shift exposure in one-third stop increments is only about one-sixth of a stop.

In other words, in the worst case scenario your exposure would be off by about one-sixth of a stop if you used one-half stop increments instead of one-third stop increments. For many (if not most) typical photographic scenarios, an exposure “error” of one-sixth of a stop won’t create any insurmountable problems for the photo.

That said, there are certainly situations where greater precision can be helpful. For example, with a scene that contains extreme contrast, having the ability to adjust exposure in one-third stop increments could help maximize the amount of detail in the extreme highlights or shadows, by virtue of being able to set the exposure with greater precision.

When it comes to the ISO setting, I think it is worth keeping in mind that the primary impact of the ISO setting is noise. Raising the ISO enables you to achieve a faster shutter speed, for example, but at the cost of additional noise in the final image.

Having the ability to adjust ISO in half-stop increments helps ensure you can adjust the overall exposure settings while minimizing the increased noise in your captures. I personally prefer the efficiency of being able to adjust exposure more quickly when it is necessary by adjusting the ISO setting in full-stop increments.

To be sure, raising the ISO setting by a half-stop more than is really necessary for a particular scenario will generally result in more noise in the photo than you could have otherwise expected. I tend to be somewhat conservative with increases in the ISO setting in any event, so to me this isn’t a serious concern. In addition, most newer cameras provide rather good performance when raising the ISO setting to moderately high values.

So, I prefer to use one-half stop increments for my exposure settings, and full-stop increments for my ISO setting. But there are certainly many photographers who prefer greater precision for these adjustments, and I certainly appreciate that perspective. In other words, this largely comes down to a personal decision for each photographer, choosing a balance between precision and the potential speed of exposure setting adjustments.

Content-Aware Cropping

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Today’s Question: I just noticed there is now a “Content-Aware” checkbox for the Crop tool in Photoshop. When would this apply, and do you recommend using it?

Tim’s Quick Answer: The Content-Aware feature for the Crop tool is used when you set the crop box outside of the boundary of your photo. My general recommendation is to only use this option for situations where the area being added to the image is relatively simple, such as when extending the sky a little.

More Detail: When we talk about cropping a photo, generally we’re talking about removing part of the image. However, it is also possible in Photoshop to extend the crop box beyond the boundary of a photo, adding additional space in the image. This is especially likely, I find, when you are rotating the image along with cropping, such as to correct a horizon that isn’t straight. In order to get the crop you want, you may end up with a triangle of space where one corner of the crop box extends outside the image area.

Under normal circumstances without the Content-Aware feature, the extra space added by a crop box that extends beyond the boundary of the image would be filled with the current background color defined on the color picker at the bottom of the toolbox.

If you turn on the “Content-Aware” checkbox on the options bar for the Crop tool, and the crop box extends beyond the boundary of the image, then when you crop the image the empty space will be filled using the Content-Aware technology.

So, for example, if you are rotating the image to straighten the horizon, you might find that a crop that remains within the image area will cut off part of a cloud formation you particularly like. If you extend the crop box to include the full cloud formation, the crop box would extend outside the image and you’d end up with (by default) a white triangle in that area of the photo.

With the “Content-Aware” checkbox turned on, that empty space would instead be filled through the use of the Content-Aware technology. If the surrounding area of the photo is relatively simple, this will generally produce very good results. If the area is a bit complex, with textures and shapes that will make any duplication obvious, this feature can be problematic.

So, for simple situations I recommend using the Content-Aware feature for the crop tool. For more challenging circumstances I recommend leaving this option turned off, and then using a combination of the Content-Aware Fill command along with the various image cleanup tools to fill in the empty area in a way that will not be problematic in the final image.

White Color Labels

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Today’s Question: Some of my photos in Lightroom show up with the color labels I have assigned to them, but others show up with a white color label. What does a white color label mean, since I don’t see any way that I can assign a white color label myself?

Tim’s Quick Answer: A white color label in Lightroom indicates that a color label has been assigned to a photo, but the definition for that label doesn’t match any of the colors available. This situation is caused by different software using different terms for the individual colors available for the color label feature. You can’t actually assign a white color label, other than by intentionally creating a mismatch among color label definitions.

More Detail: When you add a color label to a photo, you aren’t really assigning a color to the image. Instead, you’re adding a word to the Label field in metadata.

Since the color label feature is implemented with the assignment (and display) of a color to a photo, it makes sense that the Label field would be populated by the name of the color assigned to a photo. So, for example, when you assign a color label to a photo in Lightroom, the Label field will be populated with the word Red, Yellow, Green, Blue, or Purple.

Other software might use different words for the Label field when you assign a color label. One of the more notable examples is Adobe Bridge. Instead of using words that define the actual colors, when you assign a color label in Adobe Bridge you are adding the word Select, Second, Approved, Review, or To Do.

If you see a white color label when you expected to see a red color label, it could mean that the word Select was assigned via a red color label assignment in Adobe Bridge. Since by default Lightroom is looking for the word “Red” rather than “Select” to define a red color label, when it finds the word “Select” (or any other word that hasn’t been defined in Lightroom as a color label) then a white color label is displayed instead.

If you have this sort of mismatch among some of your metadata, you can certainly update your metadata based on your newer workflow. If you had only been using Adobe Bridge, for example, and then started using Lightroom, you could change the definition of color label values in Lightroom to match those from Adobe Bridge. You can find those settings by choosing Metadata > Color Label Set > Edit from the menu.

You could also update your “outdated” color label assignments from Adobe Bridge in Lightroom. For example, you could use the Metadata tab of the Library Filter Bar (View > Show Filter Bar from the menu) to view all of the current names being used for color labels, and filter for individual names. Using the example above, you could filter for color labels that were assigned the word “Select”, then select all of those images and assign a red color label to update the word used in the Label field for those images, and thus update the display of the images to a red label rather than a white label.

To learn more about cleaning up metadata and other “messy stuff” in your Lightroom catalog, check out my “Cleaning Up Your Mess in Lightroom” video course bundle here:

http://timgrey.me/atgmess

File Size Confusion

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Today’s Question: Why is it that a JPEG on my desktop says its 947KB and when I open it in Photoshop it says it is 14.4MB?

Tim’s Quick Answer: In this case Photoshop isn’t reporting the actual file size on your hard drive, but rather the total amount of data based on pixel information. In other words, Photoshop is not taking into account the compression that will be applied when you save an image as a JPEG file.

More Detail: The file sizes that can be displayed on the status bar below the image window in Photoshop don’t actually report file size, but instead report what is referred to as the document size. There are actually two document sizes displayed, which can provide you with an idea of what sort of file size to expect for an image, but only for certain circumstances.

If you display the Document Sizes option on the status bar below the image, the file size indication on the left represents a flattened version of the image, and the file size indication on the right represents a layered version of the image.

In other words, the first number can be thought of as the file size you could expect if you saved the image as a TIFF file with no compression applied, but with all layers flattened. The number on the right is the estimated file size if you save the file as a TIFF image without compression and with all layers intact.

When you save an image as a JPEG image, it will always be a flattened version of your document in Photoshop, because JPEG images can’t contain layers. In addition, JPEG images always have compression applied to them. That compression helps to reduce file size, though it also has a negative impact on overall image quality. That is why a JPEG is good for sharing in certain contexts, but not ideal as a “master” image file format.

In addition, you can adjust the “Quality” setting for a JPEG image, which impacts not only the overall image quality but also the file size. But again, the Document Sizes information display that is available for the status bar for your photos relates more to the amount of information contained in the image you’re working with, which doesn’t directly translate into the actual size of the file that will be saved on your hard drive.

Corrupted Catalog

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Today’s Question: I just tried to load my Lightroom catalog and got a message it is corrupt. I tried all the suggestions Lightroom made to no avail. Any suggestions? I have a week-old backup, but will lose a fair amount of data if I have to utilize it.

Tim’s Quick Answer: I would first make some additional efforts to open the catalog, but failing that would want to either restore from a backup or re-import into a new catalog if you had enabled the option to automatically write metadata updates to XMP.

More Detail: Naturally the ideal solution here would be to regain access to the Lightroom catalog that has become corrupted. Unfortunately, if the catalog has become corrupted there isn’t much chance that you’ll be able to recover it. However, you might try quitting Lightroom and then confirming that none of the temporary files are included along with your Lightroom catalog. One simple way to test this out is to copy the corrupted “lrcat” file (the actual catalog file) to a different location, and then double-click to open that catalog file in Lightroom. If that fails, chances are you won’t be able to recover your catalog.

If you had previously enabled the “Automatically write changes into XMP” on the Metadata tab of the Catalog Settings dialog in Lightroom, you can recover most of the information from your corrupted catalog by simply creating a new catalog and importing all of your photos into that catalog, using the “Add” option at the top-center of the Import dialog.

It is very important to keep in mind that some information from your original catalog will be lost if you take the approach of creating a new catalog and importing all of your photos into that catalog. For example, pick and reject flags, membership in collections, the history in the Develop module, virtual copies, and some other details that relate to Lightroom-specific features are not written to your images when you enable the “XMP” option noted above. However, all standard metadata such as star ratings and keywords will be retained if you had previously enabled the “XMP” option in the Catalog Settings dialog.

The last option, as noted in the question, is to recover from the most recent catalog backup. Obviously this means you will lose any information that was added to the corrupted catalog since the time of your last backup. You may therefore need to update information for some of your photos, and even re-import photos that had been imported after your latest backup. But at least this approach will provide you with most of the information that would have otherwise been lost in the absence of a backup.

This type of situation does underscore some of the challenges associated with the use of a catalog in Lightroom. There are many advantages to having that catalog as well, but it is very important to protect yourself from the risk of corruption of your Lightroom catalog, through frequent backups and other workflow practices.

Changing Backup Location

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Today’s Question: You suggested backing up the catalog to the same external drive as the one used for photo storage. Currently my backup is stored on my MacBook Pro. Where do I make this change? I don’t see a setting for that in Preferences.

Tim’s Quick Answer: The location where you want to store the backup copy of your Lightroom catalog can actually be specified within the actual backup dialog that appears when it is time to create a new backup of your catalog.

More Detail: Within the Catalog Settings dialog you can specify the frequency for backing up your Lightroom catalog. The options include backing up daily, weekly, monthly, every time you exit Lightroom, or never. In addition, there is an option to backup the next time you exit Lightroom. However, within the Catalog Settings dialog (as well as the Preferences dialog) there is not an option to specify the location where you want to store the backup.

Instead you can specify the backup location within the Back Up Catalog dialog. The Backup Folder label identifies the current location for your catalog backup, which by default will be the same folder location as your actual catalog files. As noted in yesterday’s Ask Tim Grey eNewsletter, I recommend storing the backup in a location separate from the catalog.

Within the Back Up Catalog dialog you can click the Choose button to the right of the Backup Folder label where the existing path is indicated. You can then choose a new location for your backup, such as the external hard drive where you store your photos if that is the approach you use. Once you change the backup location, that will remain the location for the backup of the current catalog unless you change the location again in the future.

Catalog Backup Location

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Today’s Question: My question is when I exit Lightroom and want to backup files where should I direct it to backup? I have an external hard drive and I back it up using GoodSync. I know my photos are on my external hard drive, but I am just wondering where to store my backup.

Tim’s Quick Answer: I recommend backing up your Lightroom catalog to an external hard drive. If you are using an external hard drive as the primary storage location for your photos, I recommend using a folder on that same drive as the location where your Lightroom catalog backups are stored.

More Detail: When it comes to making a backup of your Lightroom catalog, I feel it is important to ensure the backup is stored in a location that is different from the location where the source catalog is stored. After all, if you need to recover from a backup because the hard drive containing your Lightroom catalog failed, your only option will be to recover from a backup on a different storage device.

By default Lightroom will store the backup of your catalog in the same general location as the original catalog. I recommend changing that default location to a drive that is separate from the drive where your catalog is stored.

If you store your photos on an external hard drive, I think it makes perfect sense to backup your Lightroom catalog to a folder on the same external hard drive where you store your photos. This approach has the added advantage of ensuring that when you backup your photos you are also backing up your backup copies of the Lightroom catalog, providing additional redundancy.

Of course, if you store your Lightroom catalog on an external hard drive along with your photos, then I would recommend storing Lightroom’s backup of the catalog on a different hard drive, such as the internal hard drive on your computer. The key is to store backup copies separate from the source files being backed up.

Remove Chromatic Aberration

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Today’s Question: Is there any reason not to turn on the “Remove Chromatic Aberration” checkbox in Lightroom for every image, without bothering to check whether the image has chromatic aberrations in the first place?

Tim’s Quick Answer: I consider it very safe to enable the “Remove Chromatic Aberration” correction for all images, though there is a chance that saturation will be slightly reduced along contrast edges within the photo.

More Detail: The “Remove Chromatic Aberration” checkbox found in the Lens Corrections section of adjustments in the Develop module in Lightroom (and also available in Adobe Camera Raw) enables you to apply an automated correction for chromatic aberrations (color fringing) in your photos.

This feature is very convenient, and for about half the images I work on that include chromatic aberrations, simply turning on this checkbox will remove the color fringing to the point that no further correction is required.

Because the “Remove Chromatic Aberration” feature is looking for color variations along contrast edges, there is some risk that saturation will be slightly reduced along some of the contrast edges in your photo that didn’t exhibit chromatic aberrations. However, this impact would affect such small areas of the photo that I don’t consider it a significant concern.

Therefore, I would feel perfectly comfortable enabling the “Remove Chromatic Aberration” checkbox for all photos. You can even streamline that process by either updating the default adjustment settings for the Develop module, or by creating a preset that you apply during import for all photos.

Healing Tools in Photoshop

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Today’s Question: What is the difference between the Spot Healing Brush tool and the Healing Brush tool? They seem to provide the same capabilities.

Tim’s Quick Answer: There are two key differences between the Spot Healing Brush tool and the Healing Brush tool. The Spot Healing Brush tool includes the “Content-Aware” technology, and the Spot Healing Brush tool also chooses the source of each image cleanup area automatically.

More Detail: To be sure, the Healing Brush tool and the Spot Healing Brush tool are very similar to each other. Both enable you to perform cleanup work in your images, removing blemishes and other distractions by replacing those areas with pixels taken from other areas of the photo.

The Healing Brush tool is the more basic of these two tools. It does not include the Content-Aware feature that is available with the Spot Healing Brush tool (and that is also found in other tools in Photoshop). That does mean that in some cases the Spot Healing Brush tool is the better choice for cleaning up blemishes in complex areas of your photos.

In addition, with the Healing Brush tool you need to choose the specific source area for pixels that will replace blemishes within your photo. So if, for example, you wanted to use the Healing Brush tool to remove a dust spot from the sky, you would first hold the Alt/Option key while clicking on a clean area of sky, and then paint over the blemish to replace it with a copy of the source pixels.

Because the Spot Healing Brush tool chooses the source area automatically, you don’t need to choose a source of cleanup pixels yourself. Simply paint over blemishes within your photo using the Spot Healing Brush tool, and Photoshop will cleanup the blemish for you automatically.

In general the Spot Healing Brush tool provides more advanced and automated cleanup. Therefore, it is often the first tool I go to when I need to cleanup a blemish in a photo. However, in some cases the automation that is included as part of the Spot Healing Brush tool can produce results that aren’t quite ideal, in which case you might want to exercise a little more control over the cleanup work by using the Healing Brush tool instead. And of course there are other cleanup tools that may be helpful in certain situations as well.