Luminance Masking allows you to control the contrast of your image in specific tonal ranges. In this article you will learn how to use the included set of Actions to make a quantum improvement in the contrast of your images.
These masks will intensify the detail and tonality of your images and add snap and sparkle that is not possible without using either this technique or one of a number of plug-ins that do this under the hood. One big difference is that this process is free.
If you are ready for some intermediate to advanced photoshop discussion continue onwards, read the article, download and use the actions and get excited like I did when I started using this process in 2007…
Once the photograph has been taken, and HDR composited if necessary, and is ready to be adjusted. This is where you can apply your tonal post-visualization of the scene to the digital original.
Because your eye is a much more perfect imaging device then the camera often photographs do not appear as you saw, or imagined you saw, them at the time of capture.
To make these after the fact contrast adjustments you can use Luminance Masks. I have created a set of actions for Photoshop that will allow you to rapidly produce the masks for your image. The generation of the mask action is beyond the scope of this discussion, as you want to learn to use the masks rather then make mask action sets. If you are generating the masks for a large image be patient as it will take a few minutes depending on your station.
A luminance mask is essentially a band pass filter that passes a range of tones while excluding tones that are not included in the band. As with any band pass filter there is a degree of interaction outside of the band as the roll off (or rejection) of values outside of the selected range is not absolute.
You can create any number of masks for your image but it is easiest to think about using them as two or three band contrast equalizers. Once a the basic contrast ranges in an image have been equalized it is easy to add more specific regionally limited masks to your image.
A two band equalizer has two levels layers. One is a LPF, lo pass filter, and a HPF, high pass filter. The two bands allow you to alter the shadows or the highlights independantly.
A three band equalizer adds a mid-range filter to provide for Low, Middle and High levels layers. Usually you will see the effects of the band pass filter in the levels layer’s histograms. I commonly use 0-III for low, V for middle and VII for high.
The mask is a continuous tone B&W representation of your image. If you plan on doing major retouching do it before you start the masking process. If you wait until the luminance masks are added you will have to flatten the image and then do the retouching. You will need to flatten your image for sharpening as the image is contained in the masks as well as the background pixel layer.
To name the masks I made a series of exposures of a test target placed on each of the zones with my Nikon D200 and Canon D5 Mk II. The tone curve/rendition was set to normal. I cut those frames up and made gray scales from the swatches. I then made a set of luminance masks of the gray scale and by loading each selection I named the mask by the zones that were primarily selected. The masks will select tones outside of those that are named but will affect them to a lesser extent. The illustrations below show the roll off characteristics of each mask.
Zone 0-IX from 2 Cameras
I made a set of masks using the ramp and scales from the above file. I loaded each selection and set it as the transparency mask on a solid color layer. This clearly illustrates the range of tones selected by each mask. You can see the roll off characteristic in the filters by the steps that are not 100% selected.
Zone O-III enables you to both lighten your shadow values and add contrast to them. I use the 0-III mask frequently as it has good rejection in the high values and gives solid coverage in the low range.
Using 0-V or O-IV and VI-IX layers provides a nice 2 band solution.
Zone V covers the midtone areas with a band pass that is centered on zone 5. I use the Zone V mask all the time as it lets me tune up the midtone values without too much effect in the highlights and shadows. I like using a three band process.
Zone V-VII is a smooth mid tone mask that can add detail and punch to the high mid-tones.
Use this or Zone VII-IX with 0-V for a nice two band contrast adjustment.
Zone VII-IX is good for building up the detail and contrast in your highlights.
I use the Zone VII mask all the time to add some detail and punch to my highlights. Cranking up the low on this will add detail to a flat detail-less highlight and pumping up the high will create sparkle.
Zone VIII-IX can give detail to flat light highlights.
This mask is good for tuning the highest highlights.
Step by Step Use of the Masking Action Set