Today’s Question: Why am I not able to ever select “Depth” from the Range Mask popup for targeted adjustments in Lightroom Classic? For every image I can only choose “Color” or “Luminance”, even though I can see that Depth is also on the popup but disabled.
Tim’s Quick Answer: The Depth option for the Range Mask control is only available for images with an embedded depth map, such as photos captured in Portrait mode with an iPhone.
More Detail: The Range Mask controls enable you to refine a targeted adjustment in Lightroom Classic based on luminance values, color values, or distance from the camera. The Depth option on the Range Mask popup relates to distance from the camera and requires that the image has an embedded depth map that defines the distances within the scene.
When you capture a photo in Portrait mode using an iPhone, for example, the camera determines the distance from the camera for the various elements in the scene. A depth map is created, which uses shades of gray to map out the distances throughout the scene. That depth map is embedded in the photo.
The iPhone uses the depth map to determine which portion of the image should be sharp versus blurred to create a narrow depth of field effect. However, other software can also make use of that embedded depth map, such as to apply targeted adjustments.
Lightroom Classic is able to employ the depth map to refine a targeted adjustment, with the Graduated Filter, Radial Filter, and Adjustment Brush. For example, let’s assume you have applied a targeted adjustment that darkens the image in a gradient from top to bottom. That adjustment would of course affect the entire image in a gradient fashion.
With the Depth option for the Range Mask feature, you can limit that graduated adjustment, so it only affects areas of the image that represent a particular range of distances from the camera. So, for example, you can have the graduated adjustment only affect the background of the image, without affecting a foreground subject.
While this ability to refine a targeted adjustment is impressive, it is important to note that the accuracy of the range mask is somewhat limited. I often see artifacts in the depth map that cause targeted adjustments to not be precisely applied to the intended areas of the photo.