Brightness adjustments using Selective Color and luminosity masks

I recently started experimenting with Selective Color adjustment layers. Normally I rely on Curves and Levels for brightness and contrast adjustments, but in reading about and experimenting with Selective Color, it definitely has some advantages, especially when adjusting the light and dark tones in combination with luminosity masks.

The image I’ll be working with is shown below. After looking at a print for a couple of days, I realized it could use more drama, especially in the sky−darker clouds, a bit more contrast, and perhaps additional texture. (You can roll the mouse over the image to see the final result. It may take a few seconds for the second image to load. Rollovers probably will not work in the email feed, so please visit the blog if you want to see rollover images.)

The Selective Color Properties panel has a drop-down menu of colors. The panel’s sliders are labeled with CYMK colors, but they actually allow hue, saturation, and brightness to be independently adjusted for any item chosen from the list once you understand how this panel works. For this tutorial, the “Whites” and the “Blacks” will be of primary interest. Using the “Whites” and “Blacks” to adjust image brightness (and to some degree contrast) has the advantage of avoiding the saturation and color shifts associated with using Curves and Levels for this purpose. With Curves and Levels adjustments, saturation and color changes become mixed in with brightness/contrast changes, and it’s hard to separate them out.

The best way to see this is with a strong “S-Curve” equivalent adjustment using different types of adjustment layers. The S-Curve adjustment increases contrast−the lights get lighter and the darks get darker.

In the Selective Color adjustment, the “Whites” correspond to the light values in the image and “Blacks” correspond to dark values. In order to create an “S-Curve” equivalent, the “Whites” from the drop-down menue need to be less black and the “Blacks” need to be more black. The screen shots below show the two Selective Color adjustments necessary to produce a strong “S-Curve” equivalent adjustment.

A similar adjustment for a Curves adjustment layer is shown below. Lights get lighter and darks get darker. (This curve shape is where the name “S-Curve” comes from.)

The results from these two similar adjustments, however, are definitely NOT similar. Below is the result from the Selective Color adjustment. Rolling the mouse over the image shows the result of the Curves adjustment. What’s immediately obvious is that the Curves adjustment has undergone a strong saturation shift compared to the Selective Color adjustment. All colors are more intense as a result of the S-Curve on a Curves adjustment layer. This does NOT happen in the Selective Color adjustment because the “Neutrals” in the drop-down menu, which basically correspond to the midtones in the image, have NOT been adjusted. Only the “Whites” and the “Blacks” were adjusted. It’s the midtone values that cause the color and saturation shifts in Curves and Levels adjustments. With Selective Color, it’s possible to leave these midtones (“Neutrals”) untouched, and the result is increased contrast without significant color and saturation changes. (NOTE: As an experiment, select the “Neutrals” and then move the “Black” slider to the right to add more black. There will be a sudden and pronounced shift in color saturation. This clearly demonstrates how the midtones are the source of the color and saturation shifts seen with Curves and Levels, where the midtones cannot be so easily excluded.)

With Curves and Levels adjustment layers, it’s common practice to change the blending mode to Luminosity to counteract the saturation shift, and the image below, which shows the Curves adjustment layer set to Luminosity blend mode, shows that this does indeed help. However, there are still color shifts, and the rollover (which shows the Selective Color adjustment) shows that they are still present. It’s most obvious in the blues of the lower clouds, but also somewhat visible in the reds and yellows. So when it comes to avoiding color and saturation shifts, Selective Color has an advantage even after changing the blending mode of the Curves adjustment to Luminosity.

For the adjustment to this image, I ended up using only the full-on “Blacks” Selective Color adjustment that darkened the “Blacks” as much as possible. The light tones in the image really didn’t need any lightening so the “Whites” were not changed. The result of this initial adjustment is shown below.

This adjustment is definitely too aggressive for my taste, but that’s intentional. It provides a good starting point for using luminosity masks. A luminosity mask can be used to filter this adjustment only to those tones that really need it. In doing so, much of the exaggerated adjustment will be concealed by the mask. The end result will be a more balanced adjustment that blends in perfectly to the rest of the image.

In this case, I experimented with Darks, Midtones, and Zone masks and found that a Zone 4 mask added as a layer mask did a nice job of creating the desired effect. The result after adding the layer mask is shown below. The rollover shows the adjustment without the luminosity mask in order to see how seamlessly the mask blended the adjustment into the image.

The ease at which a preset luminosity mask finished this adjustment points out another possible advantage of using the Selective Color adjustment. And that is that it works well to create an initial adjustment to a broad, but limited, range of tones (“Whites” or “Blacks”), which can then be quickly and accurately refined with a luminosity mask. It’s almost like having a targeted double-masking technique where a strong targeted adjustment is first applied, and this can then be fine-tuned and focused using the narrower tonal range of a luminosity mask.

The video below shows the entire process for this adjustment that accomplishes the goal of adding drama in the sky. It uses the RapidMask2 panel’s Layer Mask Mode to quickly find the right luminosity mask for the adjustment. There is also a similar adjustment to a second image included in the video that uses the “Whites” instead of the “Blacks.” If you’d like to practice along with the video, a smaller jpg version of the unadjusted image is available here. (The download image will probably open in a browser window. Right-click on it and choose an option to save it on your computer, and then open it in Photoshop.)

SUMMARY−Adjustments to brightness (and to some degree to contrast) using a Selective Color adjustment layer helps avoid the saturation and color shifts associated with Curves and Levels. Additionally, Selective Color adjustments allow a two-step adjustment process where the initial, somewhat extreme adjustment can be easily modified by applying a more targeted luminosity mask to the adjustment layer to better control which tones in the image are affected.

FINAL NOTE: Every image is different and there’s likely no single workflow with Selective Color and luminosity masks that will work the same repeatedly. I’m finding that using Selective Color to adjust the “Whites” and “Blacks” provides expected and desirable results once I find the correct luminosity mask as demonstrated in the video. It’s always possible to return to the Properties panel to tweak to the initial Selective Color adjustment if necessary.