Luminosity Masks for Black and White
Being mostly a Nature photographer producing color images, I occasionally get questions about the applicability of luminosity masks to other genres such as portraits, wildlife, autos, and black and white. I always respond that luminosity masks work equally well on any continuous-tone image regardless of the subject. Luminosity masks select specific tonal ranges in the image, and since all photographs are composed of tones, they all can use luminosity masks to adjust these tones. It’s just a matter of finding a way to select the desired tones and then making the necessary adjustment.
Along this line, I thought I’d provide examples of a few adjustments from a recently developed black and white image. The before image (straight RAW conversion with no adjustments) is shown below. A mouse rollover shows the final image. (NOTE: Depending on the speed of your Internet connection it may take a few seconds for the rollover image to appear.)
I did a basic conversion to black and white in Adobe Camera Raw and then brought the image into Photoshop where I did the rest of the processing with luminosity masks. There were three adjustments that made the biggest difference for this image. The first was a luminosity painting layer. I wanted to improve the cloud texture and enhance the contrast between the clouds and the background in the lower part of the image. To do this I made a new layer, filled it with 50% gray, and changed the blending mode to Overlay. This became the “Dodge” layer for selectively lightening the clouds. Brushing white paint onto this layer has the effect of lightening anything on the layers below. In order to target just the clouds, a Zone 8 luminosity selection was created (mask shown below). It selects the tones in the clouds (lighter areas) without selecting the non-cloud parts of the image (darker areas).
As I painted through this selection, the clouds (lighter areas) received white paint and are lightened, but the adjacent non-cloud (dark) areas receive no paint and remain unaffected. The Zone 8 selection guides the paint onto the layer so that it is perfectly applied to lighten the clouds without spilling onto the non-cloud areas. The effect this has on the image is shown in the before and after (rollover) images below.
The “Dodge” layer is reproduced below. It shows that the Zone 8 selection was extremely precise in depositing paint exactly where it was needed. Even the delicate fringes of the clouds are properly painted without straying onto the mountains behind. Luminosity painting through a luminosity selection can provide this “automatic accuracy” when burning and dodging. In addition, the effect can be built up to the degree that looks right for the image by varying brush opacity and applying multiple brushstrokes. So it’s highly customizable and the results often look completely natural.
A second technique that helped this image involves the use of a quarter-tone mask. These are narrow tonal range selections that have their midpoints near the quarter tones of the image. The highlight quarter tones selection peaks around a gray value of 200 and the shadow quarter tones selection around 56. These are off-center midtone selections, so they aren’t locked into the lightest or darkest tones in the image. They feather tonally into both lighter and darker tones and their use is often accompanied by a favorable contrast change.
In this case, the shadow quarter tone mask (which I refer to as “3/4”) was used on a Curves adjustment layer. The layer’s blending mode was changed to Multiply, which darkens the image. This 3/4 mask served as the layer mask and controlled which parts were darkened. It is shown below.
The before and after (rollover) images for the change provided by this layer is shown below. It’s subtle, but the adjustment definitely strengthens the darker parts of the mountain without dragging down the highlights.
When I want to do selective tonal lightening or darkening of an image, these quarter-tone masks combined with either Screen (to lighten) or Multiply (to darken) blending mode are something I try because it often produces a pleasing result. I actually find using the Screen and Multiply blending modes effective in many situations where a luminosity mask is the layer mask on a Curves or Levels adjustment layer. Instead of bending a curve or positioning a slider in this set-up, the layer’s opacity is simply adjusted to achieve the desired effect.
The last adjustment that made a significant difference to this image is one where I’m not entirely sure what I did. It involves a Curves adjustment layer set to Multiply blending mode, so it was another darkening adjustment. The adjustment was selectively applied through what appears to be some type of hybrid painting technique of the mask. In this case, a hide-all (black) mask would have had white paint brushed on to reveal the darkening adjustment of the layer. The painted mask is shown below.
A luminosity selection was obviously painted through to reveal of the sky and the tops of the mountains since the outline of these are clearly visible. But there is also some painting around the lower edges that appears to been performed with no active selection. I don’t recall exactly what was done and have been unable to duplicate it.
Despite the uncertainty of exactly how it as accomplished, this adjustment did a nice job of strengthening the sky texture and providing better overall tonal balance between the clouds in the sky and the mountains. The before and after (rollover) images are shown below.
This last adjustment shows that there is a certain degree of spontaneity in using luminosity masks. Not every adjustment requires just one mask or one way of using that mask. The photographer responds to what the image needs and selects the tools they wish to use to accomplish the desired goal. It’s important to not get locked into thinking that there is one mask that will make everything perfect. Luminosity masks are simply tools that can be used in multiple ways. There is no prescribed path and experimentation is always an option. They offer a versatile tool set for working with tones in all types of images.
A small PSD file of this image showing the entire workflow can be downloaded at the bottom of this page.