Recommendations for Luminosity Masks


Today’s Question: I continue to see references to luminosity masks and I am confused. Are there distinct advantages to using luminosity masks [in Adobe Photoshop] versus what can be accomplished readily with other software?

Tim’s Quick Answer: A luminosity mask is simply a layer mask (or selection) that is based on brightness levels in an image. These enable you to target adjustments to only the highlights or shadows in an image, for example. I highly recommend using the Color Range command rather than the various shortcuts that are often what I find most photographers are referring to as luminosity masks.

More Detail: Most often, when I hear photographers talking about luminosity masks, they are referencing techniques where selections are created somewhat automatically based on the brightest or darkest pixels in an image. These approaches are interesting, but I find the Color Range command in Photoshop to be far more flexible for this purpose.

A luminosity mask is most helpful when you want to apply an adjustment to all of the brightest areas of a photo or all of the darkest areas. The Color Range command makes it easy to create a selection of those areas with control over the specific range of tonal values being selected. You can even create a selection based on middle tone values rather than highlights or shadows.

To get started, open an image and choose Select > Color Range from the menu. In the Select popup at the top of the Color Range dialog choose the option that suits the area of the image you want to select, which for luminosity would mean choosing either Highlights, Midtones, or Shadows.

Once you have selected an option you will see a Range control. For Highlights or Shadows this enables you to define the cutoff between what is a highlight versus a shadow for purposes of the luminosity-based selection. For Midtones you will have two sliders that enable you to define the range of tonal values to be selected.

You can also fine-tune the Fuzziness slider to expand or contract the selection relative to similar tonal values. When you’re finished click the OK button to create the selection. That selection can then be used as the basis of a targeted adjustment for specific areas of the photo based on the luminance values.

GPS Tracking


Today’s Question: For someone without a GPS-enabled camera (Nikon D500), is there a smartphone app you would recommend? Are there free programs for someone who would not be doing large volumes? Or even though there is significant battery drain would you recommend a camera mounted devise? Any other thoughts on the subject?

Tim’s Quick Answer: I am currently using (and would certainly recommend) the GPS Tracks app for iPhone users ( I’m not as familiar with Android smartphones, but do have one and have used GPS Logger for Android (, and found it to work very well.

More Detail: If your camera is not equipped with a GPS receiver, I find that recording a track log using a smartphone app is a great solution. I’ve generally been able to record track logs of nearly a full day with a smartphone app. By using your smartphone for this purpose rather than a GPS accessory for your camera, you will prevent the additional battery drain for your camera caused by such an accessory.

For iPhone users, I recommend the GPS Tracks app, which you can find in the Apple App Store here:

For Android users, the app I’ve used with good results is GPS Logger, which can be found here:

With a GPS track log app such as those mentioned above, you can record a log of your position and movement during a photography outing. When you’re finished recording the track log, you can download a GPX file that contains the track log data. I find it easiest to use the app to email the file as an attachment.

That GPX file can then be synchronized with your photos to add location information to the photos based on the data recorded in the track log. For example, I use the Map module in Lightroom Classic to load the track log, and then synchronize that track log with the photos captured during the time I was recording the log.

Naturally, if you’re using a camera with a built-in GPS receiver the process of adding location metadata to your photos can be completely automatic. Of course, even with such a camera you may prefer to record a track log to prevent the additional battery drain caused by the GPS antenna on your camera.

JPEG versus JPEG 2000


Today’s Question: What is the difference between JPEG 2000 and JPEG, and which would you suggest using? I accidentally saved a photo as a JP2 (JPEG 2000) and couldn’t open it in some programs to look at them. I found out what I had done and saved them as JPEG and was able to open the saved photos.

Tim’s Quick Answer: JPEG 2000 is a file format that was originally intended to replace the JPEG file format, with both having been developed by the Joint Photographic Experts Group. For a variety of reasons, including intellectual property concerns, the JPEG 2000 format has not achieved broad adoption.

More Detail: The JPEG 2000 file format that employs an image compression algorithm that provides a variety of improvements over the original JPEG standard that was created in 1992. Among other things, the JPEG 2000 file format provides the option of lossless compression, meaning the image quality is not degraded with this compression option. By comparison, the original JPEG format always involves lossy compression, where some image quality degradation will occur even at high quality settings.

While the JPEG 2000 standard represents a number of improvements over the original JPEG standard, there were a variety of intellectual property concerns that resulted in slow adoption of the format. With many software applications not supporting JPEG 2000, naturally many users (including photographers) were not eager to adopt the format.

Adobe Photoshop supports the JPEG 2000 format, but Lightroom Classic does not. In addition, some web browsers do not support JPEG 2000. Due to the lack of broad support for the JPEG 2000 format, I don’t generally recommend using it.

In addition to saving the original capture and any high-quality derivative images, if you were looking to archive copies of photos with a smaller file size, I suggest using the PNG (Portable Network Graphics) format, which is now widely supported and enables you to save files without the lossy compression of the JPEG file format.

Lightroom in a Web Browser


Today’s Question: You said that it was possible to view photos synchronized from Lightroom Classic from any computer using Lightroom in a web browser. How do you do that?

Tim’s Quick Answer: You can view photos from all collections synchronized via Lightroom Classic on your computer by signing in with your Adobe Creative Cloud account after pointing your web browser here:

More Detail: Adobe Lightroom has developed from being an application to a complete ecosystem for managing your photos. While much of this ecosystem revolves around the “cloud” version of the Lightroom desktop application, you can also make use of the cloud synchronization features with Lightroom Classic.

As mentioned in yesterday’s edition of the Ask Tim Grey eNewsletter, you can synchronize photos from Lightroom Classic using a collection. Start by adding the photos you’d like to synchronize to a collection in Lightroom Classic. Then make sure synchronization is enabled for the collection.

When synchronization is enabled for a collection, you’ll see a double-headed arrow icon that (to me at least) resembles a lightning bolt. If synchronization is not enabled, when you hover the mouse pointer over the collection, you’ll see an empty box to the left of the collection name. Click that box, and synchronization will be enabled.

After synchronization is complete, you can view your photos from any version of Lightroom, including Lightroom in a web browser. Simply sign in with your Adobe Creative Cloud account to get started, after pointing your web browser here:

Once you are signed in, you’ll see an interface that is very similar to the mobile version of Lightroom that you might already be using on a smartphone or tablet. There you’ll find the collections you synchronized from Lightroom Classic, containing all of the photos from those collections.

The Role of Collections


Today’s Question: I have been using Lightroom Classic for a number of years and have created new collections with some regularity. However, it seems I almost never return to the collections unless I am creating one. How and when should I be using collections?

Tim’s Quick Answer: To me collections in Lightroom Classic are first and foremost a method of organizing photos beyond the folder structure on your hard drive. In general, I recommend using collections for specific projects, or for synchronizing photos to other devices for sharing. I think it is also important that just because collections are available in Lightroom Classic doesn’t mean you necessarily need to create collections all that often.

More Detail: Collections in Lightroom Classic can most certainly be a helpful feature. However, I think it is worth keeping in mind that just because a feature exists in a software application doesn’t mean you should necessarily make use of that feature. If collections are helpful, by all means put them to use. If you don’t find a need for them, that’s perfectly fine too.

Most photographers develop a folder structure to help them keep their photos organized. The folder structure you establish on your hard drive is reflected within Lightroom Classic, and of course when you make changes to your folder structure within Lightroom Classic those changes are reflected on your hard drive.

Sometimes, however, you may find that you want to organize photos beyond the folder structure. Perhaps you want to put together a slideshow of photos from a single trip. Those photos are likely all in the same folder, so a collection wouldn’t necessarily provide a significant advantage. However, if you want to create a calendar featuring photos from a wide variety of folders, a collection could be very helpful.

In addition, in Lightroom Classic you synchronize selected photos to the Creative Cloud (and thus to other devices such as a smartphone) through the use of collections. If you add photos to a collection for which synchronization has been enabled, those photos can be viewed and shared using the mobile version of Lightroom on a smartphone or tablet, or from virtually any computer using Lightroom through a web browser.

So, collections can be useful for various projects, or just for organizing your photos beyond the folder structure. But creating a large number of collections without necessarily having a need for those collections will increase the amount of clutter and confusion in your workflow.

Laptop Over Desktop


Today’s Question: Your post [which referenced using a laptop computer exclusively without using a desktop computer] piqued my interest regarding doing away with using a desktop. I can’t imagine doing all the work I do on a laptop and am curious if you wouldn’t mind sharing the rationale or just give the advantages of laptop over desktop, at least for you.

Tim’s Quick Answer: My original rationale for abandoning a desktop computer was quite simple. I got to the point that I was traveling so much that I wouldn’t have access to a desktop computer that remained at home while I was away. In the approximately ten years since I started only using a laptop computer, I’ve never missed having a desktop computer.

More Detail: Before the current pandemic caused my travels for the year to be canceled, I was scheduled to be traveling for almost ten months of this year. If I had a desktop computer sitting at home, I would hardly ever be able to use it.

Around ten years or so ago, as my travels were starting to get more extensive, I originally had a desktop computer at home that I could remotely access with an Internet connection. However, if something went wrong with my desktop computer, I might lose remote access for the remainder of a trip. That could prove problematic.

So, I opted to make a laptop the only computer I use. Not only does that mean I don’t have to manage a desktop computer at home, but it also means I never have to swap data between computers. I have access to my core applications and data anywhere I go as long as I bring my laptop. And I typically have my photos and other data with me as well, as long as I’ve brought my external hard drives.

Even though I haven’t traveled in the past six months due to the pandemic, I still find it advantageous to use a laptop computer exclusively. This setup makes my work more flexible, with the ability to switch locations at any time, take my laptop with me, and still have everything I need.

To be sure, you can potentially get faster performance with a typical desktop computer compared to most laptop computers. There are certainly times when I wish my laptop was as fast as the top desktop computer. I also wish I could have more internal storage on my laptop, so I wasn’t as dependent on external hard drives. But on balance, I’m happier using a laptop, and can’t imagine ever getting another desktop computer.

Provenance of DNG


Today’s Question: How can I tell if an image is raw? I know that the file extension can be helpful to tell if a file is in raw format. Usually. But what if I do something like export a JPG file to DNG from Lightroom Classic? And then I import a different Canon raw capture as a DNG. How can I look at the two DNG files and determine which one is a true raw image?

Tim’s Quick Answer: I don’t know of any software that makes the task of identifying the source of a DNG file particularly easy or reliable. However, you can open a DNG file with a text editor and search for an indication that the file was converted from a different file type.

More Detail: With a proprietary raw capture format, you can essentially just tell from the file type that the file is indeed a raw capture. The same is not true for an Adobe DNG (Digital Negative) file.

A DNG could be an original raw capture, as a variety of cameras support raw captures saved directly as a DNG file. You can also convert a proprietary raw capture to the DNG format, with the option to embed the original raw capture in the DNG file if you’d like. Both of these would provide you with a file that could be considered a raw capture.

However, it is also possible to convert other image file formats to DNG. You could, for example, capture a JPEG image with a smartphone and then convert that JPEG image to a DNG file. This represents a DNG created from a non-raw source, meaning there is full color information for all pixels in the image, unlike most raw capture formats. This type of DNG file is referred to as a Linear DNG.

If you open a DNG file with a basic text editor on your computer, you can search for the text “converted”. With the software I’ve tested (which in this case only includes Adobe software), a DNG file that was converted from another file format will include text in metadata describing the conversion. For example, a JPEG I converted to DNG includes the text “converted from image/jpeg to image/dng, saved to new location”.

Viewing a DNG file this way isn’t the easiest task, and you need to be very careful not to make changes to any of the text and save the modified file, as that can corrupt the image.

If any readers are aware of software tools that streamline the process of determining the provenance of a DNG file, please let me know and I’ll be happy to share that information.

Safely Removing Media Cards


Today’s Question: Why does it matter if I remove a photo storage card without ejecting it from my iMac and get this “Disk Not Ejected Properly” message?

Tim’s Quick Answer: The reality is that as long as data is not being written to the media card (or other storage device) there is virtually no risk of harm. That said, I do recommend playing it safe and using the option to safely remove storage media before disconnecting it from your computer.

More Detail: The risk involved with not ejecting or safely removing is that files (or the entire storage device) could become corrupted. This is really only an issue if data is actually being written to the storage device. If you disconnect a storage device while data is being written, the data will be written incompletely, and one or more files may be corrupted.

When you are downloading photos from a media card to your computer, data is being read from the card but not written to the card. Therefore, there isn’t any risk of corruption to the card since no data is being written to the card. In other words, no change is actually being made to the card itself.

That said, I do recommend using the option to eject or safely remove the media card using the applicable feature in your computer’s operating system. I simply consider this a good habit to be in, as it can help ensure you don’t ever disconnect a storage device while data is actually being written to it, even though that isn’t a concern when simply downloading photos from a media card.

Note, by the way, that in the Import dialog in Lightroom Classic there is a checkbox you can turn on that will cause the card to be safely removed automatically when the import is complete, so you don’t need to take the extra step of using the operating system feature when downloading photos.

Photo Filter Color Values


Today’s Question: Did you happen to find a way to match Wratten numbers with HEX numbers or RGB values? For example, what is the HEX code of an 81A warming filter?

Tim’s Quick Answer: While I’ve not determined the specific color values of the original Wratten filters, you can get an approximate color value for some of them using the Photo Filter adjustment in Photoshop.

More Detail: Today’s question was a follow-up to an old article I wrote about fifteen years ago on the subject of photo filter effects with digital processing. In Photoshop, that means using a Photo Filter adjustment layer.

The Photo Filter adjustment in Photoshop provides the ability to add a color tint to an image, enabling you to mimic the behavior of some of the colored filters that were often used in film photography. In fact, some of the presets for the Photo Filter adjustment represent approximations of the effect from some of the standard warming and cooling filters.

You can also select any color you’d like from the Color Picker when using the Photo Filter adjustment. Start by selecting the desired preset from the Filter popup. For example, you can get a warming effect with the “Warming Filter (81)” option. This will change the color of the color swatch associated with the Color option, and you can click that color swatch to bring up the Color Picker dialog, showing you the color values for the filter you selected.

I have discovered that there is a slight problem with some of these presets, in that not all of them use proper color management. What that means is that for some of the filters you will get a different color depending on which color space you are working in. The differences are not too significant, however.

So, you can use this technique to determine Photoshop’s version of the color you would apply to achieve the approximate effect of certain color filters. In the Color Picker dialog you can see the actual color values for the selected filter. Note that you can also adjust the overall strength of the effect with the Density slider for the Photo Filter adjustment.

XUME Adapter Magnet Worries


Today’s Question: I have a concern relating to the magnetic portion of the XUME Adapters you have recommended. Since it would be stored in my camera bag in close proximity to my memory cards, my hard drive and, worse yet, my camera with its internal computer memory, should I be concerned about the possible impacts of the magnetic fields? Or, is it weak enough that it would be of no concern?

Tim’s Quick Answer: Most of the items you mentioned use flash-based memory rather than magnetic storage, and so magnets would not be a concern. If your hard drive is a traditional drive (rather than an SSD) I would tend to keep the XUME Adapters at a distance, but the reality is that it takes a very strong magnet to cause problems for a hard drive.

More Detail: I am a huge fan of XUME Adapters (, since they make it so incredibly easy to add or remove a filter (such as a solid neutral density filter) to the front of a lens.

These adapters employ magnets. One piece attaches to the front of a lens, and the other piece attaches to the filter. You can then simply put the filter in place at the front of the lens, and the magnets hold the filter in place until you choose to remove it.

The magnet in the XUME Adapters is adequately strong to hold a filter in place, but not strong enough that I would be concerned about it being near a hard drive. And flash-based media (such as memory cards or the memory buffer in your camera) would not be a concern at all.

By the way, you can see a (very old!) video of me demonstrating the use of XUME Adapters on my “Tim Grey TV” channel on YouTube here: