Processing a Monochrome Infrared Image in Photoshop

April 13, 2019  •  Leave a Comment

590 nm filter, 105 mm, 1/250 sec, f/8.0, ISO 100

After I had my camera converted for infrared photography, I knew I would have to start processing more images in Photoshop. Infrared images come out of the camera in the same RGB files that the camera produced before it was converted. But instead of red, green, and blue wavelengths of visible light, those RGB pixels now represent some combination of other wavelengths of invisible light-RAW image processors like Lightroom are simply not set up to work with these types of images. Working in color to produce false color infrared images typically involves swapping the red and blue channels in the image data so that skies are some shade of blue and foliage appears as a warm hue. Lightroom (or other RAW processors) can be used to create black and white images from infrared photos, but generally do not offer enough control to produce "fine art" monochrome images.

What I did not realize-and that became abundantly clear to me when I opened my first infrared image in Photoshop-was that I had absolutely no clue how to post-process an image in Photoshop. I mean, where is the Clarity slider? I learned how to process RAW images in Lightroom, and so I have used Lightroom almost exclusively to process all of my regular landscape photos. I had learned just enough Photoshop to get by when I needed to accomplish something that can't be done in Lightroom such as blending exposures or adding specific artistic flairs like an Orton effect. But for basic image enhancement, I didn't know where to begin.

So for the past two months, I have been intensively studying image processing in Photoshop, particularly focusing on black and white conversion and artistic processing of monochrome images. I'm certainly not an expert; but I'm at the point where I think I'm ready to process some of the infrared photos I've captured in the last month, and I have learned that, when in doubt, use Curves.

The farmhouse image is one that I've been wanting to develop, but my first attempts did not turn out well at all. When I was in the field taking the photos, I did not realize the dramatic differences in lighting that were occurring as the sunlight filtered through the clouds. In infrared, the sun was like a spotlight that in this particular image was shining directly down on the old house and the grasses on the horizon. Unlike regular photography where I seek to enhance the images to match what I saw and felt capturing the image, with infrared I didn't see the scene this way at all. To my eye, it was all dead brown grass and blue-gray clouds, and I was getting really tired of the southwest wind blowing my hair in my face. But for me, this is one of the most fun and exciting aspects of infrared photography-with images made of invisible light, I am free to be as creative and imaginative as I want with how I develop those images. In my mind, I could see the farmhouse almost glowing beneath the turbulent clouds. The challenge then is how to develop the image to achieve that artistic vision.

I have previously written about how the RAW file was processed for further editing in Photoshop. For the remainder of this post, I want to describe the layer stack in Photoshop, mostly for my own benefit so that I have a written explanation of my decisions, but also to provide an example workflow.

Black and White Conversion

I used dual Black and White Adjustment Layers to convert the RAW image to monochrome. In the primary monochrome conversion, the yellows and blues were lowered causing the sky, farmhouse, and foreground vegetation all to appear darker.  A basic contrast adjustment using Curves was also included at this stage with this adjustment. I used a second Black & White adjustment layer with a clipping mask applied to a copy of the RAW color image to layer in lighter versions of the house, bright clouds, and the clump of grass in the lower left by increasing the blues and yellows.

Artifact Removal

One of the issues with this particular image were some horizontal lines in the smooth shadow areas of the sky that appeared after some strong contrast adjustments. I've never observed these in images from this camera previously, but I'm also not sure I've ever pushed the pixels as hard either. It is something I will keep and eye out for and I may check with LifePixel to see if they have an explanation. Nevertheless, with this image the problem was sever enough that I needed to remove the lines. I tried using various noise reduction approaches, but those only smoothed the lines without removing them. Ultimately, I found that the Surface Blur Filter on a stamp layer was very effective. This was applied only to shadow areas in the sky by painting in through a Darks luminosity mask to limit loss of detail from the blurring.

Tonal Adjustments

The next set of layers are contrast adjustments using Curves. Curves is the primary tool for making tonal adjustments in Photoshop. I think it will take a lot of practice to master, but the approach I am trying to learn is to make several small adjustments that build upon one another to produce the desired result in the image. I used a group of multiple Curves adjustment layers with some Soft Light blending layers plus an additional Curves layer at the end to correct the white and black points. This set of layers accounts for most of the tonal adjustments in the image.
The first group includes six Curves adjustment layers created using Raya Pro 3 with luminosity masks to target different contrast zones in the image (two each for Highlights, Shadows, and Midtones). The group of Soft Light blending layers were used to darken the sky. These were also created using the Darken Sky tool in Raya Pro and use a solid black pixel layer with a Brights luminosity mask set to Soft Light blend mode to enhance contrast. I used two of these layers to enhance the effect and added a group mask to apply the effect only to the sky.

After the tonal adjustments, I added a Camera Raw Filter on a stamp layer primarily to use the Clarity slider (set to 50). The Clarity adjustment was faded into the shadows using BlendIf. I also added a radial filter in Camera Raw to bring down the highlights in the bright clouds above and left of the house. At this point, the image was about 95% done and the remaining layers were used to add some artistic and finishing effects.

Artistic Effects

I wanted this image to have a somewhat dark, moody feel. The clouds over the house were actually the precursors of a supercell thunderstorm that arrived a couple of hours later and sent our family into the basement three times when the tornado sirens were activated. I mentioned before how the wind was howling with the outflow from the approaching storm system, and it was actually the lightning that sent me running back to my car just after I captured this image. So I wanted some of that atmospheric instability to be present in this image.

To darken the image and bring in some of that moody feel, I used a technique I learned from Jim Welninski. I don't know what it is called, but it uses a blurred stamp of the image set to the Multiply blend mode, so I call it a Blur Multiply. I added a layer mask to lessen the effect on the foreground and bright clouds in the sky, then lowered the opacity of the layer to 33 percent. I added an Orton effect layer above the Blur Multiply layer, also using a foreground/highlight mask and even lower opacity of 12 percent to limit the effect.

I also wanted to emphasize the sunlight on the house, I added a Curves adjustment layer set to Screen with a black layer mask, then brushed in the light coming in from the top of the image to create more of a spotlight glow on the house.

Finishing

At this point I was happy with the overall mood and tone of the image, but it still needed some finishing touches. It was a little bit dark after adding the artistic effects, so I used a Curves adjustment layer to brighten the image just a little. Then I added a custom vignette, another technique I learned from Jim Welninski, using a Curves adjustment layer with a layer mask. The general shape of the vignette is created with the lasso tool to create a selection on the layer mask, then a Gaussian blur is applied to feather the vignette. Even with the vignette, I felt that the top and bottom needed to be darkened to close the image, and there were some distracting bright clouds right along the top border. I used two layers to burn the top and bottom and darken the distracting highlights.

I decided to add film grain to this image-it seemed to fit the aesthetic of the old abandoned farmhouse. Grain was added through the Blur Gallery filter on a smart layer.

The final touch in Photoshop was split toning. The split toning was initially added in Lightroom, but I wanted to see if I could achieve the same effect in Photoshop. I used a Gradient Map adjustment layer to apply the color toning, but my first attempts were unsuccessful. Since I was trying to match the effect applied in Lightroom, I first edited the gradient to match the hue and saturation of the highlight and shadow tone colors (at 50 percent brightness), but the effect was still not right. The key was to change the blend mode of the Gradient Map layer to Linear Light then reduce the fill to 50 percent. (And yes, I could have also used the Camera Raw Filter, but that requires the addition of a stamp layer.)

Final Adjustments in Lightroom

To finalize the image, I cropped it to a 4:3 aspect ratio and then applied a post-crop vignette in Lightroom. The final image is at the top of this post.


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