Author: Tim Grey

Today’s Question: You recently addressed a question related to 8-bit versus 16-bit per channel bit depth. But I notice there is also a 32-bit per channel option in Photoshop, which doesn’t seem to get talked about very much. Is there ever a reason to use 32-bit per channel?

Tim’s Quick Answer: As far as I’m concerned, the only reason to employ the 32-bit per channel bit depth option in Photoshop would be to apply adjustments to a high dynamic range (HDR) image that has not yet had tone-mapping applied to it.

More Detail: Generally speaking, I recommend working in the 16-bit per channel mode when applying adjustments to your photos. This provides the potential of more than 281 trillion possible color values, which helps ensure images will retain smooth gradations of tone and color even with very strong adjustments.

When sharing images through digital means, such as via a digital slideshow or when sharing online, you can save a copy of the image that has been prepared for that purpose, such as to reduce the overall pixel dimensions and to convert to the 8-bit per channel bit depth. This still provides more than 16.7 million possible color values, which is in line with the estimated number of color values that can be perceived by normal human vision.

The 32-bit per channel mode provides an absolutely huge number of possible tonal and color values. In fact, the number of possible color values is so large (just under eight with 28 zeroes after it) that you couldn’t display it on most calculators without using scientific notation. That’s a lot of potential color and tonal values!

The reality is that this 32-bit mode is a “specialty” mode used for high dynamic range (HDR) images. For a normal photographic image this mode would not provide any value at all. In addition, an image saved in the 32-bit per channel mode will have a file size that is twice as large as the same image in the 16-bit per channel mode.

Even if you assemble an HDR image, you won’t generally have a 32-bit per channel image as a result. That’s because the HDR image will be converted to 16-bit per channel mode for the tone-mapping stage of creating the final image. It is possible, however, to generate an HDR image in Photoshop as a 32-bit per channel image. Very few adjustments will be available in 32-bit per channel mode, but you could then use Camera Raw to perform the tone-mapping for the image and save the final result as a 16-bit per channel image for further processing.

Today’s Question: Is there a way in Lightroom Classic to globally change the time zone by half an hour? In Australia there is a 30-minute difference between Eastern Standard and Australian Central time. When I try doing a global change I can only change in increments of plus or minus 1 hour.

Tim’s Quick Answer: Yes, you can correct the time for a group of photos by 30 minutes (or any needed increment) using the “Adjust to a specified date and time” option in the Edit Capture Time dialog.

More Detail: If you neglected to set the correct time zone on your camera, you can generally correct all the affected photos in one step by using the “Shift by a set number of hours” option within the Edit Capture Time dialog. Of course, in situations where you need to correct by something other than a full hour, that option won’t provide a solution.

You can, however, adjust by any number of minutes or hours needed, with an option that doesn’t seem like it would provide a solution when you need to correct multiple photos.

To get started, determine the correct time for the first image you’ll select among the group of images that need the same correction applied to them. For today’s question the correction needed is thirty minutes, but you may find in some cases that you need to apply a different amount of correction. Let’s assume in this case that the first photo in the series of images needing correction has a capture time of exactly 8:00am, but the correct time should have been 8:30am.

Next, select the photos you need to adjust the time for. I would start by selecting the photo you used to determine the correct time, and then hold the Shift key on the keyboard and click on the last image in the range that need to be selected. The key is to make sure that the photo you are basing your correction on is the active photo. To be sure, after selecting all of the photos that need correct, click on the thumbnail (not the frame around the photo) for the image you have calculated the correct time for.

You can then initiate the time correction by choosing Metadata > Edit Capture Time from the menu. Under the Type of Adjustment heading select the “Adjust to a specified date and time” option. The active photo will be shown on the left side of the Edit Capture Time dialog, and the existing capture time from metadata for that image will be shown as the Original Time under the New Time heading.

Use the fields to the right of the Corrected Time label to update the date and time of capture for the active image based on the correction needed. In the example above that would mean changing the capture time to 8:30am rather than 8:00am.

Click the Change All button, and all photos will be adjusted by the same amount of time, not to the exact same capture time. So, for example, we used a photo captured at 8:00am as the starting point, and that photo would be updated to show a capture time of 8:30am. A photo captured at 8:15am would be updated to reflect an 8:45am capture time, and so on.

Today’s Question: I just got a new laptop and loaded Photoshop onto it. I saved two images from Photoshop, thinking they would go to my external hard drive as usual. However, when I tried to open them, I can’t find them. When I look at the “Save As” dialog, it looks like the only choice is to save to the cloud. How do you find images if they got saved to the cloud?

Tim’s Quick Answer: You can locate recently saved images by choosing File > Open Recent from the menu. To save files to your computer rather than the Adobe Creative Cloud servers, click the “On your computer” button at the bottom-left of the Save As dialog.

More Detail: Photoshop enables you to save files to the Adobe Creative Cloud, which means the files will be saved on Adobe’s servers through the internet rather than on a local hard drive that you manage. However, you can still save files locally rather than to the cloud.

When the Save As dialog is configured to save to the cloud, you’ll see an indication of “Cloud Documents” toward the top-left of the Save As dialog. In this case you will also see an “On your computer” button at the bottom-left of the dialog. You can click that button to switch to the standard Save As dialog where you can navigate to a location on your computer where you want to save the file.

If you prefer to save to Cloud Documents so you can open your files from any computer that is connected to the Internet and on which you have signed in with your Adobe Creative Cloud account, make sure you’re in the Cloud Documents version of the Save As dialog. In the standard Save As dialog you’ll see a “Save to cloud documents” button toward the bottom-center of the dialog, which you can click to switch to the Cloud Documents version of the Save As dialog.

And, as noted above, if you’re not sure where you saved a recent file you can choose File > Open Recent from the menu to see a list of the files you’ve most recently saved.

Today’s Question: You said that converting an image from 8-bit to 16-bit would double the file size. So wouldn’t it be a good idea to convert my finished images to 8-bit per channel in order to cut the file size in half?

Tim’s Quick Answer: While it isn’t something I prefer to do, converting a “finished” image to 8-bit per channel mode won’t create any significant problems in terms of image quality, as long as you don’t apply adjustments to the image after that conversion.

More Detail: The primary advantage of a 16-bit per channel image compared to an 8-bit per channel image is that the former can retain smooth gradations of tone and color even if relatively strong adjustments are applied. With an 8-bit per channel image there is a greater risk of a loss of smooth gradations, because there are fewer available color and tonal values available for those gradations.

Once you are completely finished optimizing a photo there is not a significant benefit to keeping the image in the 16-bit per channel mode. This assumes, of course, that you won’t be applying additional adjustments to that image. In that case, you could convert the image to 8-bit per channel mode, making sure that you first flatten the image if it contains layers, so that you are actually converting the image after all adjustments have been applied to the pixel values.

Converting the image to 8-bit per channel mode will cut the file size in half compared to 16-bit per channel mode. So this conversion can have a significant impact on your overall storage needs. That said, I prefer to take the conservative approach of retaining the 16-bit per channel mode for my master images, and also of retaining all layers for my layer-based image.

But again, if you want to reduce your storage needs, converting high-bit images to 8-bit per channel mode is an option you could consider. I would just personally favor buying a larger hard drive before converting my images to a lower bit depth.

Today’s Question: I use Lightroom Classic to catalog my images, but I use Adobe Bridge to download my images. If I clean up Lightroom Classic by finding missing folders and images, and then rename folders inside Lightroom Classic, will I then have to go into Adobe Bridge and painstakingly rename each folder manually? Or are they somehow linked so that changes in Lightroom Classic are reflected in Adobe Bridge?

Tim’s Quick Answer: If you make changes to your folder structure within Lightroom Classic, those changes will be updated on your hard drive and thus will be reflected in the operating system, in Adobe Bridge, and elsewhere. However, if you make changes outside of Lightroom Classic, those changes will not be reflected in your catalog and instead folders and photos will appear as missing.

More Detail: Lightroom Classic makes use of a catalog, which is a database containing the information about your photos. This enables you to search, filter, and sort images across your entire catalog of photos very quickly. It also means you need to be sure to initiate changes from within Lightroom Classic, not elsewhere.

Adobe Bridge does not use a catalog to manage the information about your photos, but instead needs to review the information contained within the image files each time you browse a storage location. Because of this different architecture, changes you make through the operating system, for example, would be reflected in Adobe Bridge.

So, if you’re using Lightroom Classic to manage your photos, all changes related to your photos and storage should be initiated inside of Lightroom Classic, and then those changes will be reflected elsewhere. If you make changes outside of Lightroom Classic, you’ll create problems for your catalog.

I should hasten to add, by the way, that in part because of the above issues I strongly recommend downloading photos as part of the process of importing those photos into your Lightroom Classic catalog. I don’t recommend mixing the use of different software tools that could potentially create problems for your Lightroom Classic catalog.

Today’s Question: I’m using Windows 10 and am not able to see thumbnails of TIFF images in the Windows Explorer file system. There’s just a generic icon presented. How do we get Windows to treat us a little friendlier?

Tim’s Quick Answer: You should be able to view thumbnails for TIFF images (even with layers) on Windows as long as the “Thumbnail” checkbox is turned on in the Save As dialog when you save the image. Otherwise you may need to reset the thumbnails within Windows.

More Detail: You can enable the option to save a thumbnail as part of a TIFF image saved in Photoshop by turning on the “Thumbnail” checkbox in the Save As dialog. Note that there is also a related “Thumbnail” checkbox in the File Saving Options section of the File Handling tab of the Preferences dialog.

If you’re still not seeing accurate thumbnails in Windows for TIFF images saved with Photoshop, you may need to clear the thumbnail cache for Windows. You can find an article with information on how to correct this issue here:

https://www.windowscentral.com/how-reset-thumbnail-cache-windows-10

Today’s Question: Do you prefer a solid-state drive (SSD) or a hard drive (HD), considering read/write performance as well as lifespan?

Tim’s Quick Answer: All things considered, I very much prefer a solid-state drive to a traditional hard drive because of improved performance and good reliability, though at a higher price point.

More Detail: A solid-state drive (SSD) provides improved performance and lower power consumption compared to a traditional hard drive (HD). The main disadvantage of an SSD compared to an HD is cost, and to some extent a concern over reliability.

Comparing reliability for SSD versus HD storage is a bit tricky, because both use different methods of storage and are therefore subject to different causes of failure. With flash-based SSD storage, a failure is virtually guaranteed after a certain period of time, because the flash memory can only function for a limited number of write/erase cycles.

Still, based on typical usage, an SSD drive can be expected to last for a good five years or more before failure. Generally speaking, you can also expect warning signs before a failure of an SSD drive. As always, a good workflow for backing up your photos and other important files will help ensure you can recover from any failure.

So, all things considered I recommend opting for SSD storage if you don’t mind paying a bit extra for your storage. You’ll get improved performance and reduced power consumption. And if you get any warning signs that your drive is not performing reliably, take those warnings seriously and have the SSD tested or replaced.

You can find some of the top external SSD storage devices here:

https://bhpho.to/2VQc39P

Today’s Question: I digitized all my slides and had a service digitize my negatives. The negatives are TIFF. I noticed that they are 8-bit files. If I change them to 16-bit, will I get any benefit, or is 8-bit baked in?

Tim’s Quick Answer: No, there will not be any appreciable benefit to converting 8-bit per channel images to 16-bit per channel, and doing so will cause the file sizes to double.

More Detail: Digital images are generally created as either 8-bit per channel or 16-bit per channel. This is referred to as the bit depth, and it determines the total number of possible color and tonal values for an image.

An 8-bit per channel RGB image can consist of a total of almost 16.8 million possible color values, while a 16-bit per channel RGB image can potentially contain more than 281 trillion possible color values.

Let’s assume you had an 8-bit image that happened to contain every single one of the almost 16.8 million possible color values (the actual number is 16,777,216). If you converted that image to 16-bit per channel mode, the image would still contain less than 16.8 million colors, even though as a 16-bit per channel file it would be capable of containing almost 281 trillion color values.

Put another way, think of color values as numbers expressed with a number of digits after the decimal point that reflects the bit depth. If an 8-bit per channel color value could be expressed with the number 0.12345678, after converting that number to 16-bit per channel you could think of it as being expressed as 0.1234567800000000. In other words, the numeric value is the same, it is just being expressed differently.

If you convert an 8-bit channel image to 16-bits per channel and then start applying adjustments, the total number of colors represented in the image could certainly increase beyond the limit of an 8-bit per channel image. However, that would not create an appreciable difference that would result in improved image quality or higher color fidelity.

Today’s Question: In an email you said, “Most cameras do not capture full color for each pixel in a photo”. Which cameras do capture full color for each pixel, how do they do that, and is it better than those that don’t?

Tim’s Quick Answer: The vast majority of cameras employ a sensor where only a single color value (typically red, green, or blue) is captured for each pixel. One notable exception is the Foveon X3 sensor, which was used in Sigma camera bodies, but which has not been used in a new camera in more than ten years.

More Detail: Many photographers are familiar with the basic process employed by color film, where several light-sensitive layers are stacked together. Each of those layers is sensitive to a different color of light, and so full color can be captured.

Digital cameras in general operate differently. For each photo site on the sensor, which will translate to a pixel in the final image, a colored filter results in only a single color value being captured. That generally means that for each pixel only red, green, or blue information is captured. The “other” values, such as the green and blue values for a red pixel, are calculated after the capture using software.

The Foveon X3 sensor operates in a manner similar to film, with layers of sensors recording three color values for every pixel. While this provides a potential advantage, there are also technical limitations that create challenges. In my experience the overall image quality and noise performance of the Foveon X3 sensor were inferior to all other sensors I tested at the time.

So, when I refer to the fact that “most” cameras do not capture full color for each pixel, for all intents and purposes you can take that to mean that all current cameras use the approach of capturing a single color value for each pixel, and calculating the full color value after the capture.

Today’s Question: Lightroom Classic [as well as Adobe Camera Raw] has a slider for Tint (green/magenta) which is one of the pairs of opposing colors on the color wheel. It also has Temperature which is for blue/yellow. But there is no slider for the third pair of opposing colors on the color wheel (red/cyan). Why is that? Wouldn’t it make more sense to have a slider for each primary pair of opposing colors on the color wheel?

Tim’s Quick Answer: There is no need to have three sliders in order to be able to achieve any desired shift in colors. If, however, you prefer to work with three sliders rather than two, you could make use of the Tone Curve adjustment in Lightroom Classic.

More Detail: While there are three primary colors (red, green, and blue) in the context of a digital image being optimized using software such as Lightroom Classic and Adobe Camera Raw, there is no need to actually have adjustment sliders for all three of those channels.

A color wheel is a common tool for displaying the full range of color hues that are available within the visible spectrum. The color wheel forms something of a rainbow going around in a circle.

When you are shifting the color balance in a photo, you are effectively moving all color values for a photo in a particular direction toward a specific color. For example, the Temp (or color temperature) slider causes pixel values to shift in appearance between more blue versus more yellow.

In this way you can think of a color balance adjustment as representing a shift in direction across the color wheel. If you could only shift color values along a single axis across a color wheel, you would be very limited in the type of color adjustment you could apply. This is why software does not employ a single slider for a color balance adjustment.

With two sliders you can adjust colors in any desired direction across the color wheel, with movement along two axes. Imagine that these two axes are aligned with one that allows movement up and down, and another that allows movement left and right. That would allow you to navigate to any destination on the color wheel, though not in a straight line. Instead of moving diagonally toward the top-right, for example, you would use one movement upward and another movement to the right.

Of course, some software applications make use of three sliders for color balance rather than only two. And there’s no reason software couldn’t employ more than three sliders as well. But Adobe opted for two sliders (Temp and Tint) as the primary controls for color balance in Lightroom Classic and Camera Raw. If you prefer to use three sliders, you can make use of the Red, Green, and Blue curves with the Tone Curve adjustment.