Today’s Question: I’m confused about why it is possible to use a negative value for the Texture, Clarity, and Dehaze sliders. Doing so seems to only degrade the detail in images. Am I missing something?
Tim’s Quick Answer: Using a negative value for Texture, Clarity, or Dehaze can provide smoothing or an ethereal glow effect for an image, which in some cases can enhance the look of an image.
More Detail: While in my experience the great majority of photographers use positive values for the Presence adjustments of Texture, Clarity, and Dehaze for the vast majority of images, there are situations where a negative value can be quite helpful. These adjustments are included in all versions of Lightroom as well as Photoshop.
For example, a negative value for Texture can help smooth out fine textures, which can be helpful for smoothing skin tones for photos that include people. Doing so can also help smooth an image that looks a bit too “crunchy” such as from excessive contrast in areas of fine detail.
A negative value for Clarity can create a somewhat dreamy appearance with an ethereal glow. I find that it works especially well with backlit scenes that lend themselves to a somewhat dreamlike appearance.
Using a negative value for Dehaze will cause the image to appear more hazy with a somewhat foggy appearance. This is perhaps the least likely among the three to be used with a negative value, but it can certainly be used for a nice creative effect in some cases.
The bottom line is that I would certainly say that the Texture, Clarity, and Dehaze sliders are most helpful for most photos when used with a positive value. However, in some cases a negative value for one or more of these sliders can provide a very helpful effect for some images.

