What are Luminosity Masks?
They are masks created using the Luminosity or brightness of pixels. They are broadly similar to Highlights, Midtones and Shadows settings in the Color Range tool, but they are capable of much greater precision.
They are excellent for creating targeted selections of areas of similar brightness. They are particularly good for blending two or more bracketed exposures. They are soft masks containing mostly semi-transparent pixels so the ‘joins’ between masked and unmasked areas are usually seamless.
Creating Luminosity Masks
There are a number of ways to create luminosity masks. The masks created will be the same whichever method is used but some methods are less laborious than others.
DIY Luminosity Masks
With any image, it’s possible to create a set of luminosity masks from scratch. This is a time-consuming and laborious task which I won’t cover here. However, you may find it helpful to read more to increase your understanding of how they work.
Read more - DIYReady-made Actions
Photoshop Actions contain sequences of instructions which can carry out a wide variety of tasks. There are many downloadable actions which can be used to create Luminosity Masks. The resulting masks will all be more or less identical to each other and to any masks you have made yourself.
The following link takes you to a page with a download link of an action which will create a full set of luminosity masks along with full instructions.
Panels
A range of panels which provide an easier way to create luminosity masks are easily found online.
Free Panels
At the very least, free panels will allow you to create luminosity masks very easily. Most will have some additional features which are often very useful.
Links for two well-known, free panels are below. Tutorials on their usage are on the same pages.
Premium Panels
These panels come at a cost and, as you would expect, provide a wider range of functions. The two panels which are linked to on the right, offer a multitude of functions covering all aspects of luminosity masking (and a bit more besides!) and are excellent value for money. They are also supported by video tutorials and other forms of support.
I use Raya Pro by Jimmy McIntyre and find it a superb resource.
Using Luminosity Masks
Although I use the Raya Pro panel, this section deals with luminosity masking using the OH Luminance Masks action described above, as each different panel has its own unique way of working. Having said that, the principles of luminosity masking remain the same whatever approach is used.
The workflow for using luminosity masks isn’t so different from other forms of masking. It has 4 steps:
- Choose an area of your image which you wish to work with.
- Create a set of luminosity masks using an action.
- Select the most appropriate mask and apply it to your image.
- Adjust the masked area of your image in whatever way you wish.
1 Choose an area of your image
Look at the different areas of brightness in your image. Think about what you want to do. For example, you may wish to lighten some shadow areas or darken some highlight areas.
2 Create a set of luminosity masks
Use the OH Luminosity action to create a set of luminosity masks.
- Open the Actions panel
- Open the OH Luminance Masks Group.
- Highlight the specific action you wish to use:
- A: Create 6 each of Brights, Darks and Midtones masks.
- B: Create 6 Brights masks only.
- C: Create 6 Darks masks only.
- D: Create 6 Midtones masks only.
- Press the ‘Play Selection’ button
A set of masks will then be created. This may take a moment or two.
As you will see, there are also options to delete all masks or each group of masks.
3 Select and apply a mask
The masks that were created in Step 2 can be seen in the Channels Panel.
Let’s assume that only the set of 6 Brights masks was created.
These 6 masks will be named Brights 1 to Brights 6. They will include decreasing amounts of brightness. Brights 1 will include the largest area of brightness while Brights 6 will include the smallest area. In other words, each mask will target a progressively smaller range of pixels.
Any of these masks can be previewed in the main image window by pressing ALT and clicking on the mask icon. The image will appear in tones of grey. Black areas will not be included in the mask. White areas will be included. Grey areas indicate pixels which will be partially included.
When you are happy with your choice of mask, click the eye icon to the left of the RGB channel and click off the eye icon beside your mask icon. Your image will return to normal.
Finally, press CTRL and click on your chosen mask icon. A selection with marching ants will be shown on your image.
4 Adjust the masked area
With the selection active, you can adjust only this area in one of several ways:
- Create a new layer by pressing CTRL J. This will only include pixels within the masked area. This new layer can then be edited directly. I wouldn’t really recommend this approach!
- Adjust the masked area directly with any adjustment tool. Not a good idea as this is destructive and will alter pixels irrevocably!
- Add an adjustment layer. This will include the mask, so any adjustments you make will only affect the area you want to target. This is the best approach by far!
Example 1
The image opposite had been edited in ACR by setting white and black points only.
The colour added nothing to the image, the sky was unremarkable and the shadow areas contained little of interest.
My intention was to create a black and white image which was almost a complete silhouette.
The first step was to add a Black and White adjustment layer.
The next step was to create a mask of the sky. A set of Brights masks was created and Brights 1 was used to create a mask which included all of the sky and nothing else.
A selection was created using this mask.
A Curves adjustment layer was then added and adjusted to brighten the sky slightly.
As there was an active selection, a layer mask was created automatically so that only the sky was affected.
The final step was to create a mask which would include everything EXCEPT the sky. There was no need to create a new mask for this. The same selection of the sky was made using the Brights 1 mask and this was then inverted by pressing SHIFT CTRL I.
A second Curves layer was added and adjusted to darken everything except the sky.
Still not a great image but it serves to show what is possible with a very few adjustments.
Example 2
In this example, the two bracketed frames below were blended to create the finished image.
The brighter frame suffers from areas of the sky and some of the reflections being brighter than I wanted. My intention was to improve this by using areas of the darker frame to create a blended result.
Both frames had been adjusted in ACR. Only tonal adjustments were made. Black and white points were set and small adjustments were made to Highlights and Shadows.
Both frames were then loaded as layers in the same Photoshop file and aligned using Edit Menu >> Auto Align Layers. Even though the frames had been taken a few seconds apart with the camera on a tripod, this is always a necessary step. A small Crop was made at this point to remove areas where the two layers didn’t overlap.
The first step in any blending process is to decide which will be the base layer. This is usually the layer which is closest to the result you are aiming for. In this example, the base layer was the brighter of the two frames.
At this initial stage, the layer structure is very simple.
As in the previous example, the first step was to create a set of bright masks. I wanted to select the brightest areas of the brighter frame so I switched off the darker frame before creating the masks.
An ordinary selection was made using Brights 1 as this gave the best result, selecting only the areas where I wanted the darker image to have an effect. You will see in the mask opposite that almost none of the mask is pure white or pure black. Because of this, the masked area would have different degrees of transparency. The brighter layer would not, therefore, be REPLACED by the darker layer, but the tonal range would be influenced by it.
Next I turned on the darker layer and selected it. Then, with the selection active, I clicked Add Layer Mask at the bottom of the layers panel. This masked out all but the brighter areas of the darker image. The result is below.
A few finishing touches were then added:
- I copied the Darks layer and selected the Overlay Blend mode. The layer opacity was reduced to 50%. This added a little glow.
- I added a Hue/Saturation adjustment layer. I adjusted the Hue of the Cyans by moving the slider a tiny amount to the right. This made the blues in the sky slightly less yellow.
- I added a Curves adjustment layer which was masked so only the top and bottom of the image would be affected. I reduced the brightness of the midtones by dragging the curve down slightly.
The final result is below. Compare it to the starting point by sliding the arrow back and forth. Again it’s worth noting that a very few, fairly subtle changes have had a significant effect.