Today’s Question: In the Post-Crop Vignetting controls for Lightroom Classic [and Adobe Camera Raw] there is a Highlights slider. When I adjust this slider nothing seems to happen. What is it supposed to do?
Tim’s Quick Answer: The Highlights slider for Post-Crop Vignetting in Lightroom Classic or Adobe Camera Raw enables you to have very bright areas such as the sun in the sky overpower the vignette effect for a more realistic result.
More Detail: The Post-Crop Vignetting effect is obviously intended to provide the ability to simulate a lens vignetting effect where the edges of the frame are a bit darkened. This is a rather common behavior for wide-angle lenses, for example. In addition, you can add a more creative border effect by using stronger adjustments for the vignette controls.
As long as you’ve selected either “Highlight Priority” or “Color Priority” from the Style popup, and you have used a negative value for the Amount slider to darken the edges of the photo, the Highlights slider will be available.
If the edges of the photo don’t have any very bright areas such as lights, reflections, or the sun in the frame, then you might not see any effect when increasing the value for Highlights. However, if there is a bright area near the edge, you can create a more realistic vignette effect by increasing the value for Highlights.
For example, let’s assume you’re working on a photo with the sun in the corner of the frame. When you darken the edges of the image with the Post-Crop Vignetting controls the sun would also be dimmed down a little bit. As you increase the value for the Highlights slider, you’ll notice that the sun is “burning through” the vignette effect, overpowering the darkening in that area of the image.
By increasing the brightness for bright areas that had been darkened by the vignette, the result will look like a more natural effect. For example, when photographing a scene with a wide-angle lens that tends to produce a relatively strong vignetting effect, if you position the sun in the corner of the frame that very bright light source will overpower the vignette in that area of the frame.