Ask Tim Grey

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.

Today’s Question: My current laptop is an HP 15.6 inch with a Full HD resolution (1920 x 1080 pixels) display. As it is now, I have trouble reading the text and sliders in the sidebars in Lightroom Classic. Would you consider purchasing a laptop with even more resolution which, I believe, will make everything (text, etc.) even smaller?

Tim’s Quick Answer: I would certainly consider a laptop (or desktop display) with a higher resolution than 1920×1080, but you may want to set your display to a lower resolution when you’re working in Lightroom Classic due to the challenges of making out the text and some of the interface controls when working at a high resolution on a relatively small display.

More Detail: A high-resolution display can be helpful in a variety of scenarios. More pixels available in the display means more information can be presented at the same time. This enables you to have multiple windows arranged side-by-side, for example, or to provide adequate space for applications that have an interface with many panels and controls.

Because of these considerations, I very much appreciate a high-resolution monitor display.

Unfortunately, high resolution often means text is presented too small to really be legible. In some cases, such as with word processing software, you can zoom the document without adjusting the overall interface size, so you can read your text without compromising on the interface presentation.

The impact of a high resolution is impacted by the display size, of course. The smaller the display, the smaller the interface will appear at a high resolution. Therefore, a very high resolution on a laptop with a relatively small screen can make text especially difficult to read.

Lightroom Classic uses relatively small test in general, and unfortunately the option within Lightroom Classic for increasing font size is limited and not especially helpful. You can increase the text size by going to the Preferences dialog, which can be found on the Edit menu for Windows users and the Lightroom Classic menu for Macintosh users.

Within the Preferences dialog go to the Interface tab, and in the Panels section at the top you’ll find a Font Size popup. The default setting is “Small”, but you can change the setting to “Large”. Unfortunately, despite the reference to “Large” on the popup, the result will not be much larger than with the “Small” setting. However, you can change the display resolution for your computer when working in Lightroom Classic to have a more significant impact.

Changing the Font Size setting from Small to Large represented a change on my system from the equivalent of about an 11-point font size to a 12-point font size, which is not something I would even remotely consider to be a significant increase in font size.

On the other hand, changing the resolution for my display from an effective 1680×1050 pixels to 1440×900 pixels resulted in an improvement from the equivalent of about a 12-point font size to a 14-point font size, which certainly helped a bit more. The specific options in terms of resolution will depend upon your hardware configuration, but with high resolution displays you do have the option of operating at a lower than maximum resolution.

Hopefully in the future Adobe will provide larger text settings in Lightroom Classic. In the meantime, while I am very much a fan of high-resolution displays, you’ll likely want to work at a reduced resolution when using Lightroom Classic.

Today’s Question: You answered a question about the 32-bit per channel option but suggested that 16-bit was the most a photographer would realistically need. But my flatbed scanner claims to have a bit depth of 48-bit. Is that just marketing hype, or is there actually some benefit to this higher bit depth?

Tim’s Quick Answer: Actually, in this case the confusion comes from how the information is being presented. A bit depth of 48-bits for the scanner is the same thing as 16-bits per channel for an RGB image.

More Detail: Bit depth can understandably be a somewhat confusing topic, especially because the numbers involved can get rather big rather quickly.

Bit depth is typically described as a number of bits per channel, such as 8-bits or 16-bits per channel. Most photographers are dealing with RGB (red, green, blue) images, which have three channels.

So, if you are able to scan at a bit depth of 16-bits per channel, that is the same as 48-bit (without “per channel” on the end of it). If you have 16 bits for the red channel, 16 bits for the blue channel, and 16 bits for the green channel, that adds up to a total of 48 bits (16+16+16=48).

Similarly, you may sometimes see a bit depth presented as 24-bit, which would indicate a bit depth of 8-bits per channel for an RGB image (8+8+8=24). The key thing to keep in mind is that if you don’t see “per channel” after the indication of bit depth then you likely need to divide the number by three to determine the actual per-channel bit depth, assuming of course that the information presented was based on an RGB image.

Today’s Question: Could you please explain how to get access to the grayed-out filters in Photoshop?

Tim’s Quick Answer: When a filter is grayed-out in Photoshop, it indicates that the filter is unavailable. That generally means the current image has settings that are not compatible with the filter, and the solution would be to update the image to ensure compatibility.

More Detail: Most of the filters in Photoshop have been updated to support most image modes. However, there are still some exceptions. Some filters will only work with photos in the 8-bit per channel mode, and some are only available for images in the RGB color space, for example.

Before making changes to the image to access certain filters, I recommend making a copy of the image so that you preserve the original with maximum information. You could, for example, choose Image > Duplicate from the menu to create an additional copy of the current image.

You can then adjust the image attributes so that the unavailable filters will become available. This will most often mean converting the image to the 8-bit per channel mode, which you can do by going to the menu and choosing Image > Mode > 8 Bits/Channel.

If the image is not in the RGB color mode, that could also cause certain filters to be unavailable. To correct this issue, go to the menu and choose Image > Mode > RGB Color.

By using one (or both) of the above options, you should find that the filters that had been grayed-out will now be available. If there are any other filters that aren’t available, you would need to check the specific compatibility. For example, third-party plug-ins may have specific requirements for the image format or may have compatibility issues with certain versions of Photoshop.

Today’s Question: I have a lot of images from the country of Oman. Unfortunately, every time I ask Lightroom Classic to search for images with the keyword Oman it also shows every image with the keyword woman. It doesn’t seem to want to believe me that I’m only searching for “Oman” and I don’t want every image with “woman”. I have never seen any solution to this.

Tim’s Quick Answer: There are actually a couple of options you could use here. One is to use the “Contains Words” option for a text search, and another is to use a quick search from the Keyword List.

More Detail: Lightroom Classic provides several methods you can use to locate photos that contain keywords. Some of these are rather broad searches, which may include unintended search results as outlined in today’s question. For example, a basic search under the Text tab of the Library Filter bar will include all photos that have the characters you enter within the Keywords field, even if those characters comprise only part of an actual keyword for some of those photos.

You can, however, search for a specific keyword without including photos that don’t include that specific keyword.

First, you could use the “Contains Words” option for the text search. First, go to the Text tab on the Library Filter bar in the grid view for the Library module. You can choose View > Show Filter Bar from the menu if the Library Filter isn’t shown. Set the first popup on the Text tab to “Keywords” and set the second popup to “Contains Words”.

With these settings established, when you type a word (or words separated by commas) into the text box, only photos that contain the specific word (or words) in the Keywords field of metadata will be included in the search results.

Another option is to use the Keyword List to locate photos that include a specific keyword. Locate the keyword you want to search for in the Keyword List on the right panel in the Library module. When you hover your mouse over a keyword on that list you’ll see a right-pointing arrow to the right of the keyword. Click that arrow, and you will be taken to a search result featuring photos that contain that specific keyword.

With either of these approaches you can locate photos that contain specific keywords, without photos that simply contain similar keywords. For example, these methods would enable you to easily locate photos that contain “Oman” as a keyword, without including photos that include “woman” as a keyword without also including “Oman”.