A Luminosity Mask is a fast and easy way to create a new mask based on the brightness of image pixels. When selected, the command will fill the active layer with a mask based on the brightness of image pixels. The transparency for the layer is directly related to the brightness of the pixels.
This command works very well to mask an overlaid image such as a cloud or texture layer. You can also mask a copy of a layer to enhance only part of an image. For example, if the sky and clouds are bright, you can create an exact mask only for that area of the image and then enhance them.
Here’s how to create a Luminosity Mask:
Make any adjustments needed with the Develop filter.
Apply an adjustment layer to stylize the image.
In the Layers controls click the + button and choose the Add New Original Image Layer option. This can be useful to blend back key details.
Click the Edit Mask button on the layer.
Select the Luminosity Mask option from the drop-down. A new mask is created based upon the brightness of the image.
If the mask is showing unwanted areas, you can click on the Edit Mask button and choose Brush.
Now you can use the Mask menu to invert the mask or use the Brush tool to add or subtract from the mask.
You can also re-run the Create Luminosity Mask multiple times to generate different masks each time.
Use the layer’s blending mode and opacity sliders to blend the layer to taste.
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TIP
When editing a mask, you can press the Backspace hotkey to reset a gradient/radial mask to its default setting.
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