How To Use In-Camera Blend Modes For Multiple Exposure Photography (Pt III: Lighten Mode)

In previous posts, I described the use of the Average and Additive modes for multiple exposure photography. I wrote that these modes emulate the type of multiple exposure results that were seen in film photography. Today, we start to look at the in-camera blend modes that were not possible with film photography, but exist in the digital realm. And these modes open up a whole new avenue of imagery and creativity. So let’s dive in!

Today we will have a look at the Lighten mode. In this blend mode, as each component image of a multiple exposure is stacked atop each other, the camera software looks at each pixel location in the stack. According to Adobe, in a Lighten blend mode the computer “looks at the color information in each channel and selects the base or blend color—whichever is lighter—as the result color. Pixels darker than the blend color are replaced, and pixels lighter than the blend color do not change.” The in-camera Lighten blend mode works essentially the same way as Adobe describes (each manufacturer that offers this mode sometimes adds a little ‘secret sauce’ to tweak the algorithm).

An important result of this mathematical algorithm is that if you stack a light pixel atop a darker one, the darker one will disappear and the lighter one shows through (likewise, if you stack a darker pixel atop a lighter one, the darker one still disappears). If you change the white balance between shots you not only get a change in white balance but also get significant color shifts. I don’t understand the math in this (though I suspect it has something to do with looking at the color information in each channel), but what is clear is that this mode causes warm color shifts with resultant yellows and magentas. Here is an example that I used in a prior blog post to demonstrate this.

Because the in-camera Lighten blend mode was used to make this multiple exposure, this white door and neutral gray background has undergone multiple color shifts with white balance chnages, as well as the removal of darker pixels at any given pixel location.

© Howard Grill

The photo above is a three-image multiple exposure of a white door with a neutral gray wall around it. The darker pixels have been replaced with lighter ones. But how did the yellows and magentas come about? It isn’t just from the changes in white balance. They are the result of the Lighten blend mode!

Do I like the colors? NO! Does that matter? NO! Why doesn’t it matter?

It doesn’t matter because I wasn’t trying to generate final colors, I was just trying to generate and separate the colors in the image. Now, I have multiple separate colors in the photo, while before, I only had white and neutral gray. Had there been more colors in the original scene, I would have even more colors than I do now.

Once I have generated multiple colors, I can push those colors further apart, closer together, or completely change them using the HSL Sliders in Lightroom or any of several Photoshop tools. There are now six or seven discreet colors/tones on the door and, while I might not want any color changes on a photo of just a door, I might well like to produce varied colors in an abstract, as seen below. The Lighten blend mode gives you excellent raw material that serves as a starting point onto which you can imprint your own vision and creativity.

A multiple exposure using the Lighten blend mode. The image then had its colors altered (along with further enhancements) in Lightroom and Photoshop.

© Howard Grill

Here are several useful tips to help you get started experimenting with the Lighten blend mode:

• Set your exposure compensation to underexpose each component image. Remember that with each exposure you are replacing darker pixels with lighter ones. This means that the composite image will rapidly get brighter (risking overexposure). By underexposing, you allow the lighter pixels to add up slowly, giving you a normal final exposure. Underexpose by how much? That’s something I can’t tell you, because it depends on the tonal values of what you are photographing to start with and how many bright pixels there are in each layer (ie, if you shoot 5 images of a black wall nothing changes, as there are no ‘brighter’ pixels added). If your camera allows you to see the composite histogram after each image is added (the Canon R5 does), you will have a great idea of where your exposure stands at any point in the process.

• Recognize in your mind that whatever you photograph that is brighter will ’cut into’ and replace the darker pixels that are in your image thus far. For example, a bright sky will exclude anything it overlies that is darker.

• Similar to using the Additive mode, you can control how much of each component image shows through by adjusting your exposure compensation for any component photo. Since the mode is Lighten, the more positive exposure compensation you give any of the individual component photos, the more it will contribute to the final composite (since you are making that photo brighter in comparison to the others). This can be visualized if your camera is one that allows you to see the image ‘thus far’ after each component shot. The Canon R5 actually allows you to see it before the shot is taken, by pressing the DOF preview button.

• As noted above, changing the white balance between shooting the component images can lead to some very interesting results, as well as generating more colors for you to alter any way you like in Lightroom and Photoshop.

I know that the first time I photographed using the Lighten mode, I was totally confused and had no idea what was going on. The best way to get a feel for working in the Lighten mode is to get out and make some multiple exposures using it, while trying to predict what each exposure will do to the final composite.

I hope this information helps you understand how to use the Lighten in-camera blend mode when making multiple exposures. It is confusing at first, but it really opens up a whole new creative avenue!

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