Editing the Luma Range Mask

The Luma Mask can introduce harsh transitions along the edge of the mask in certain high-contrast circumstances. These can be mitigated by tweaking the edge coverage with the Radius and Sensitivity sliders. Be aware that the two sliders work in conjunction: the Radius slider controls (in pixels) how broad an area the edge refinement should work on. The Sensitivity slider, in turn, adds an edge/contrast detection to the Radius value. If you set Sensitivity down to 0, you will just get a simple blur/feathering effect that is seldom useful. As you increase the Sensitivity slider, the edge detection mechanism will modify the feathering by excluding any high contrast areas found. At 100, it will work similarly to the Refine Mask action. In most cases, the default value of 50 is the sweet spot, so you can concentrate on adjusting the Radius slider. A value between 0,5 to 1 pixel is a good starting point.

1. Go to the Layers tool and select the desired Layer.
   
   
2. Zoom the image at 100% to better judge the effect.
   
   
3. Click on the Luma Range… button in the Layers tool (or select it in the menu Layer -> Luma Range…
   
   
   
   
4. Enable Display Mask to see what parts of the image the Luma Range mask will affect.
   
   
   
   
5. Adjust the edge coverage with the Radius and Sensitivity sliders.
   
   
   
   
6. Once you are happy with the adjustments, click Apply to close the dialog box.
   
   

TIP: The default Mask Color Opacity is set to 50% which can make it tricky to fully evaluate how the Radius and Sensitivity sliders affect the Luma Range when you have the Display Mask option enabled. This can be changed under Preferences and Appearance. Click on Mask Color and ensure that Opacity is set to 100 percent. It can also be a good practice to change the color to something garish, like pink. This will make it easier to see whether the Luma Range does indeed affect the chosen areas.

If you find that the Luma Range mask covers specific areas that you do not want to include in the adjustment, you can brush those out with the Erase Mask (keyboard shortcut E) cursor. As an example, you might want to affect the exposure of the bride’s white dress, but not her white teeth. Note that this particular workflow is meant to be used on a mask created with the Draw Mask (keyboard shortcut B) brush. It does not work with Linear Gradient Mask or Radial Gradient Mask unless you accept to rasterize those. 

1. Create a New Empty Layer and brush over the desired areas with the Draw Mask (B) cursor tool.
   
   
   
   
2. Select the Layer in the Layers tool and click on the Luma Range… button.
   
   
   
   
3. Enable Display Mask to see what parts of the image the Luma Range mask will affect.
   
   
   
   
4. Set your desired Luma Range with the black and white Range points. Tweak the Falloff points as needed.
   
   
   
   
5. Click Apply to close the dialog box.
   
   
6. Hit the keyboard shortcut M if the mask is not already shown in the Viewer.
   
   
7. Select the Erase Mask (keyboard shortcut E) and paint over the areas that you do not want to include.
   
   
   
   
8. If you make a mistake and remove too much from the mask, select the Draw Mask (keyboard shortcut B) and paint back over the area to include it.
   
   
   
   
9. You can also add to the overall mask with Draw Mask but note that the Luma Range feature will always exclude the chosen Luminosity values. If you have excluded white, you cannot add white areas with the brush.
   
   
10. Hit the keyboard shortcut M to toggle the Mask overlay off to review that your image adjustments are made to the desired areas of the image.

The advantage of the above workflow is that you can always readjust the Luma Range in combination with tweaking the mask (by erasing areas or paint them back in).

If you need to include areas of the image that are not currently covered with the mask, you should first try to readjust the Range and Falloff points as well as adjusting the Radius and Sensitivity sliders. If that does not provide the desired result, you can change the Luma Range mask to be a normal pixel-based mask. You can then paint on it with the Draw Mask (B) or Erase Mask (E) cursor tools to add or remove areas. Note that once you make the Luma Range settings as a pixel-based mask, you lose the ability to readjust it after the fact.

1. Select the Luma Range mask by right-clicking on the Layer and choose Rasterize Mask….
   
   
   
   
2. Add areas to the mask area with the Draw Mask (B) cursor tool.
   
   
   
   
3. You can also remove areas with Erase Mask (E) cursor tool.
   
   
   
   
4. Click on the Luma Range… button in the Layers tool to create a new Luma Range mask control, if needed.
   
   

The Invert Mask option is used to create a reverse selection of a mask. This is adopted, typically, when drawing a mask on a small area and reversing the selection to include the rest of the layer is the simpler option. The option can also be used to invert the Display Grayscale Mask so that the edge and the selection could be seen more clearly. The Invert Mask option is always used on a single layer, but it can be used to copy a selection to a second layer.

One common technique, favored by fashion photographers working on location, is to make the subject stand out from the background using color to emphasize the distance between them. Although the human visual system can compensate for color differences under a mix of lighting conditions, it is hardwired into our subconscious that distant scenes such as mountain ranges always have a cool-blue look, while features much closer to hand have a warmer-look about them. This effect can easily be accomplished using layers and the Invert Mask option and the local Color Balance tool.

1. Go to the Layers tool.
   
   
2. Click on the Create New Layer button, the (+) icon, in the tool’s foot bar to create the first adjustment layer, leave as Layer 1.
   
   
3. With the layer selected in the Layers tool (indicated by an orange or silver-colored bar, depending on focus), select the Draw Mask tool from the tool's foot bar and draw a mask on the subject that you want to isolate from the background.
   
   
   
   
4. Verify the accuracy of the mask drawn, toggle Always display Mask (M) and tidy-up the mask as necessary. Use shortcuts to switch between the Draw Mask (B) and Erase Mask (E) functions.
   
   
5. To add a second mask with a separate adjustment, a new layer must first be created. Repeat step 2, leave as Layer 2.
   
   
6. Click on the Action menu, the (...) icon, in the Layers tool or Ctrl/right-click on Layer 2 and select Copy Mask From -> Layer 1.
   
   
   
   
7. Repeat and click on the Action menu, the (...) icon, in the Layers tool or Ctrl/right-click on Layer 2 the second time and select Invert Mask
   
   
   
   
8. Double-click on Layer 1 in the Layers tool to rename it. Add a meaningful name to aid organizations, such as foreground or subject. Repeat the same for Layer 2 and add a relevant name, such as background.
   
   
9. Select Layer 1 (foreground) and adjust the Color Balance tool, adding a warm color balance setting as desired.
   
   
10. Repeat the process with Layer 2 (background) using a cooler, blue-color balance setting, or a use a suitable preset.

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