5.4.7. Image luminance masks

An image luminance mask isolates an area of the image or based on tonal values. Some tasks luminance masks are useful for include:

• Applying natural color adjustments to the shadows, mid-tones, or highlights of the image, without affecting other areas.
• Protecting the shadows or highlights of an image from being affected by adjustments.
• Removing black or white backgrounds from a layer.
  

There are no viewer controls for luminance masks, but the viewer provides a real-time representation of the current mask selection, like the example in the second image above.

Sidebar controls

• Invert: Toggles between retaining (the default) or removing the selected luminance range.
• Range: These values define the size of the tonal range which will be included in the selection.
• Sliders:* Use the sliders to control what areas of the layer are visible, based on the layer contents. The top and bottom control handles are linked in pairs. The angle between the two handles in each pair controls the feathering of the selection. The slider has four control handles:
  • Bottom Black: Areas of the selected layer darker than this tone will be completely invisible. Tonal values between the bottom black and top black sliders will gradually be more opaque as they move toward the top black slider.
  • Top Black: Areas of the selected layer lighter than this tone will be completely visible. All tones within the selected layer that fall between the top black handle and the bottom white handle will be completely visible.
  • Bottom White: Areas of the selected layer darker than this tone will be completely visible. All tones between the top black handle and the bottom white handle will be completely visible.
  • Top White: Areas of the selected layer lighter than this tone will be completely invisible. The tones between the bottom white and top white sliders will gradually be more transparent as they move toward the top white slider.