Infrared Channel Swapping in Lightroom

Lightroom has had some weaknesses when it came to processing infrared images like channel swap and white balance. The primary problem has been and continues to be the range of white balance options not being wide enough into the blue end of the slider. That has had a fix for quite some time which I will quickly outline here for completeness. The second shortcoming, although not an issue for me, is the inability to swap the red and the blue channels which results in blueish skies and yellowish foliage. That had to be done in Photoshop, until the latest release of Lightroom.

The stacked images you see in the opening of this article are all done in Lightroom, including the one that has the blue sky. That is the result of the newly added capability to Adobe Camera Raw to create extensive and flexible camera profiles that can also optionally make use of the Lookup Tables (LUT.) It is this newly acquired capability allowed me to create a camera profile for my infrared-modified Canon M5 that allows me to swap the red and the blue channels without constantly going to Photoshop and retaining the workflow completely nondestructive because there is no need to open a pixel version of the image in Photoshop. Interested? Read on! Although the content may conceptually sound geeky, procedurally it is a breeze to follow, don’t let the jargon fool you. The steps are very easy to follow. 

A Camera Profile for Better White Balance Control

Although the following part can be done without this first step, going through this simple procedure will give you much better control on the white balance of your IR images. Even if you create a custom white balance in camera by photographing green grass or foliage, the white balance sliders in Lightroom do not have the range of adjustment to display that or even tweak further. Follow these steps with no thinking, at least initially:

1. Take a photograph of a grassy patch or green foliage of a plant with good coverage
2. Using your camera controls, set this image to be used for Custom White Balance
3. Take a few photographs showing some foliage and other subjects
4. Download Adobe DNG Profile Editor from their site, Mac, and Windows versions, even a short tutorial available there. It is an oldie but goodie! We are interested in doing one thing here, extending the range of the Color slider in Lightroom, nothing else
5. Open an IR photograph from your camera in the DNG Profile Editor, any photo you took in step 3 will do. Depending on your camera brand and the white balance settings you will see something similar but not exactly identical to what I show in the images below
6. Look for a tab on the top right “Color Matrices” and click on it to show the sliders
7. Move the “Blue Primary” saturation slider down to -100
8. Click on the “Options” tab and write a descriptive name for this profile
9. Now, click on File/Export and export this profile to a known folder
10. Close the DNG Profile Editor
11. Open the File Explorer and go to the folder where you saved the new profile and highlight it by clicking on it once
12. Press Ctrl-C to copy it to the clipboard
13. Navigate to C:\Users\<your name>\AppData\Roaming\Adobe\CameraRaw\CameraProfiles
14. Press Ctrl-V to paste the file into this folder
15. Restart Lightroom

Now in Lightroom, navigate to one of your IR images taken in step 3. How it will look is anybody’s guess, but navigate to the Profile Browser in its new location of the Basic Panel. You should see under “Profiles” group, the new profile you created similar to my screen capture shows. You will see in my screen capture other profiles, stay tuned for those. Click on the new profile you created and then on “Close” to exit the profile browser. You should now see a very usable set of white balance sliders most likely showing “As Shot” setting. The following images should help following the steps above:

Up to this point, we have converted the unusable white balance sliders to fully functional ones that reflect the camera settings. Now, let us see how we can do the red-blue channel swap. I will not go too much into creating and using camera profiles in Lightroom and ACR as plenty have been written on the subject. I will mainly focus on one specific profile creation that will bring the ability to swap the Red and the Blue channels to achieve results like the ones below. All three images are direct export from Lightroom virtual copies of the same raw file.

Color Lookup Tables (LUT)

The idea of using LUTs for various purposes has been around from monitor profile and calibration to applying particular looks to video files. A LUT consists of a series of color values that link the measured to desired with the necessary adjustment so that they look as desired. It is a color mapping process. The new profiling capabilities in Adobe Camera Raw along with the ability to export a series of adjustments in Photoshop as Color Lookup Tables give us the ability to apply a set of adjustments once in the exclusive domain of Photoshop to the images in Lightroom. Although I will focus on processing infrared images, the same concept can be used to create profiles for other purposes as well.

Let us create first the necessary lookup table in Photoshop. For this purpose, I used three different images with no visible difference in the exported LUT, a regular color photograph, an infrared photograph, a file with a simple black background. Photoshop seems to be exporting the changes contained in the adjustment layers rather than any image content which probably makes sense. That said, for the purpose of visual consistency, I will use the same infrared image shown above as my base image, either raw or any other format.

1. Open the image you want to use for this purpose in Photoshop
2. Add a Channel Mixer adjustment layer
3. Select the Red channel, lower the Red value to zero and increase the Blue value to +100
4. Select the Blue channel, lower the Blue value to zero and increase the Red value to +100
5. You should now see the image with the altered colors
6. Now go to File/Export/Color Lookup Tables
7. Add a description, optionally add a copyright notice, leave other options as you see in the screen capture
8. Click to save and give it a descriptive name in a folder you can easily locate. Congratulations you now have the Channel Swap LUT ready to use
9. Open the raw image in Adobe Camera Raw by noting the file name and directly opening it from Photoshop rather than sending it from Lightroom. This will launch ACR and load the raw image
10. Click on the Profiles tab at the top, and while holding the Alt key, click on the New Profile icon at the bottom
11. In the pop-up dialog window, give the profile a name, leave the default location as User Profiles, and put a checkmark in the box next to Color Lookup Table in the bottom block
12. Navigate to the folder where you saved the LUT in step #8 and load that file
13. Click OK to save the profile, it is now ready to use instantly in ACR
14. Load Lightroom and find the raw file you have been working with
15. In the Basic Panel, click on Profile Navigator, scroll down to see User Profiles, locate the new profile
16. As you move your cursor over the profile preview thumbnail you will see your image assuming that look. Now, click on that thumbnail to apply the profile.
17. You are now working with the image with its Red and Blue channels swapped. Adjust to taste.

Here are the sequential screen captures that correspond to the steps in this section for reference.

Additional Notes

I have experimented with several options and would like to share my conclusions. You may or may not agree with them, but they may point you in some additional directions to try different settings.

1. In creating the initial camera profile using the DNG Profile editor, the recommended setting for the Blue Primary saturation is -100 in many articles I have read. I did try other values, -50 and -75 and have seen subtle differences. Simply create three different DCP profiles and see how they behave in Lightroom for your taste. The only cost is the few extra minutes of saving them.
2. Read the DNG Profile Editor tutorial, it has many other paths to follow for different and even better results in your IR camera profiles. There is a very short segment about this in the manual/tutorial.
3. The creation of a Color Lookup Table in Photoshop will accommodate multiple adjustment layers and their impact on the image. I thought it might be a good idea to add a curves adjustment layer and apply different levels of contrast on top of the Channel Mixer. I found this to be helpful with moderate and strong contrast curves for quick results.
4. Additional settings may be applied in the ACR to be saved as part of the same profile such as pulling all the saturation sliders in the HSL panel to -100 to save time in Lightroom to convert the image to B&W. I found this to be a little confusing because all the sliders will remain in the middle but there will be no saturation. To regain the saturation they need to be pushed to +100 essentially shortening the slider travel distance. Sliders remaining unmoved in Lightroom may be of benefit for some sliders but not all, at least not for me.
5. If you apply the Channel Swap profile and then want to adjust the darkness of the sky or other color channels, remember they are no longer where they were before. To darken the sky you will most likely use the Red, Orange, and Yellow sliders. Likewise, the foliage may be found in the Blue, Purple, or Magenta.

Summary

The new Lightroom and ACR updates provide additional capabilities in creating and using camera profiles. The few simple features explored in the article will be welcome by most infrared photography fans. The following photograph is a panoramic stitch done in Lightroom and then adjusted using the processes outlined above without opening it in Photoshop.