Maybe! If you need the power of the curves and don’t mind a few extra steps, you can add curve adjustments to your Lightroom masks.
Lightroom Masks Gained Power
Adobe has added powerful features to masks, making Lightroom more capable than before. The newly introduced tools for selecting subjects, objects, backgrounds, and so on make using masks simpler and that much more powerful. One powerful tool missing in this collection is the use of the curve adjustments in Lightroom masks, although it is available in Adobe Camera Raw. It may be a short while before it finds its way to Lightroom, but I would like to present a workaround for Lightroom users who may want to apply curve adjustments to Lightroom masks.
Curve Adjustments via Roundtrip to Camera Raw
If you have an image that will benefit from curves for tonality and color tweaking, it is possible to push the image to Adobe Camera Raw and use the curve adjustments there. Afterward, you can continue with the rest of the adjustments and create unified collections in Lightroom.
Curves offer a tool that allows users to make both tonal adjustments and tweak the color in highlights or shadows at the same time. Surely this can be done by using several different masks, the method I will share will offer another tool for this purpose and quite likely accomplish all that in one mask.
In Lightroom From Global to Local Adjustments
The general advice in editing images in any software is to move from global adjustments to local adjustments. Using this approach, make your global adjustments that apply to the entire image like white balance, tonal structure, highlight, shadows, and the like.
When the time comes to apply local adjustments using masks, say to adjust the color in the clouds and the sky to convey that warm feeling, you may resort to using a mask. As I said earlier, you may be able to use multiple masks for different adjustments, but curves may give you one tool that can handle tonal structure and can make colors in the highlights different from the shadows. You can select the mask in Lightroom or Camera Raw, that makes no difference.
Before Pushing to Camera Raw
I suggest creating the mask in Lightroom for the sake of minimizing external handling. So, using the masking tool in Lightroom, I will select the sky. But, this could be the person in a portrait, the background in a still life, and the like.
Once the sky or the needed mask is created, click on the Mask icon to close and save the mask with no adjustments. At this point, there may be plenty of adjustments in Lightroom and we must retain all of them in the round trip to Camera Raw. To accomplish that, right-click on the image you are editing and select Metadata/Save Metadata to File option. Lightroom will create an XMP file containing all the edits for ACR to read and apply.
Open the File in Camera Raw
Do not rush and select to edit the file in Photoshop. That will create a pixel version and push it to Photoshop. Instead, while the image is selected in Lightroom, right-click the mouse and select Open in Explorer, or press Ctrl-R in Windows. Mac users, try to open the counterpart of Windows File Explorer with the image file highlighted.
Now, the file you have been working on is highlighted in Windows Explorer. (There must be a Mac counterpart like Show in Filer.) In Windows File Explorer, right-click on the selected file and find Open With. Then select Adobe Photoshop 2023.
In Camera Raw
First thing first! Click on the Mask icon on the right vertical toolbar to display the mask, or masks if you have applied others for different purposes. Select the one you would like to adjust using curves and look for the Curve tool block. As you can see in the first image below, the adjustments came through from Lightroom. And, in the second image, you can see the mask active with the Curve adjustment block displayed.
When using curves, you need to remember that a little may go a long way. You can adjust the tonal structure using the luminance curve that will control the brightness and contrast of the selected area. In addition, you can also select each color channel, Red, Green, and Blue, and make adjustments to the colors in the selection.
Keep in mind that although you are working with three color curves, they affect the named channels and their complementaries in the secondary color channels. The pairs are Red-Cyan, Green-Magenta, and Blue, Yellow. As you increase one in a pair, the other gets lowered. By pulling the red channel curve from its middle down, you will reduce reds and add more cyans to the midtones for example. For the above image, I made the following adjustments in luminance, red, green, and blue channels.
When you are done with the curve adjustments on the masked area, feel free to make other adjustments if you like. Then close the mask panel by clicking on the mask icon on the vertical toolbar on the right. When you are ready to ship the image back to Lightroom, click on Done.
Do not open the image which will convert it to pixel-based Photoshop format and you will not be able to carry the adjustments in the raw file. Make sure to click Done which will save all the edits back to the XMP file.
Back in Lightroom
After you are done in Camera Raw, switch back to Lightroom. You will most likely not see the results of your edits in Camera Raw yet. Right-click on the image you have been working on and select Metadata/Read Metadata from File. It will ask you to confirm that choice, click to make it happen. Suddenly, the image will change to reflect the results of the curve adjustments on the masked area.
You can select that mask and make other adjustments to it if necessary except you cannot control the curves in Lightroom. You can now continue with the work and apply other adjustments, maintain stylistic conformity with others in a collection and complete your project in Lightroom. Here are the before and after images side by side.
Why Go Through This Trouble
At this point, many readers may be asking why not do all the editing in camera raw instead of this back-and-forth. If you are comfortable in Camera Raw, by all means, do everything in that. However, keep in mind that it does not have a catalog feature and you need to either open the files from Windows (or Mac) file explorer one at a time. Alternatively, you may use Adobe Bridge and push the files from Bridge to Camera Raw. But, as you can see, there is no “just Camera Raw” option.
Another reason for keeping the files in Lightroom and then pushing them to Camera Raw as needed may be to maintain a uniform look of a collection of images by making similar adjustments in Lightroom to all of them. There is also cataloging, keywording, creating collections, and other things you may do in Lightroom.
Please keep in mind that I selected the sample image on purpose because it has a blue building which would have made it very difficult to use the HSL adjustments to control the sky. Also, I may have gone slightly overboard with the curve adjustments to show what it can do. If it looks too much, it can be reduced in Lightroom or ACR by using the Amount slider on top of the mask adjustments block.
Like all other options, this approach is a tool, not a rule. One more in your toolbox. Use it if you like, and dump it if you don’t!