Un-Erase on Gradient


Today’s Question: I have used the graduated filter in Lightroom to reduce exposure (darken the sky) and have erased non-sky portions of the effect. In the course of doing so, I erased a bit of sky by mistake. I can’t figure out how correct the mistake without completely redoing the whole erasure. How do I restore the bit of sky I erased to the original graduated filter effect?

Tim’s Quick Answer: Solving this challenge can be quite difficult in terms of producing a result that blends together well. Switching to “unerase” mode is simply a matter of choosing the “A” or “B” brush option after switching to the Brush setting for the Graduated Filter (or the Radial Filter). However, when you use the “A” or “B” brush option the adjustment effect will be revealed completely, overriding the gradient you had already added. You can, however, use the Density setting to help blend the effect.

More Detail: The Graduated Filter creates, as you would expect, an adjustment that transitions from one side of the image to the opposite side. For example, you can darken the sky and have that darkening effect taper off toward the horizon.

Using the Brush option within the Graduated Filter, you can choose the Erase setting and then paint within the image to erase the adjustment effect. For example, if an object extends into the sky that is being darkened by the Graduated Filter, you can paint over that object with the Erase setting so that the adjustment does not apply in that area.

If you accidentally paint with the Erase option outside of the object and into the sky, the easiest approach may well be to simply undo your last brush stroke. This is problematic if you have painted a large area in a single stroke, but this also provides an argument in favor of working with small brush strokes to provide greater flexibility.

In situations where you need to return to an area you had erased an adjustment from in order to reveal small portions of the adjustment, you will want to make use of the “A” or “B” brush option to reverse the effect of the Erase brush option. However, this isn’t as simple as you might have hoped.

When you paint with the “A” or “B” brush for the Graduated Filter (or the Radial Filter), you aren’t simply revealing the effect of the gradient, but rather are replacing that gradient with a 100% adjustment effect in the area you paint. In other words, the area you paint will no longer include a smooth gradation for the adjustment.

You can overcome this limitation to some extent by carefully adjusting the Density setting for the brush. The challenge is to find the right setting, which can take a bit of trial and error. You might, for example, use a very low setting for the Density slider, such as 10% or 20%. Then set the Feather value to the maximum of 100%, so that you are getting the maximum amount of blending. You can then paint multiple times over a given area to build up the effect to achieve a good blend.

Of course, all of this careful work will go by the wayside if you then decide to change the shape of the gradient you created with the Graduated Filter. If you change the size of the transition or the position of the gradient, the area you carefully painted will no longer match up.

These various issues demonstrate some of the shortcomings of the targeted adjustment features within Lightroom. While it can be tremendously helpful to be able to combine the effect of the Graduated Filter with the Adjustment Brush in a single combined mask, you still don’t have the degree of flexibility and control that is available in Photoshop.

As a result, I tend to use Lightroom only for relatively basic targeted adjustments. Even then, I am careful to make sure that any painting I have done on the mask for the targeted adjustment is highly accurate. But for layer masks that require precision, or where I want to preserve maximum flexibility, I will send the image to Photoshop rather than working within Lightroom.