Mastering Lightroom’s adjustment brush is one of the best ways to avoid taking all your photos into Photoshop or Elements after your Lightroom edits.
If you need an overview of using the Local Adjustment Brush in Lightroom, read this tutorial. Today I’m going to dive in more deeply and cover the difference between the Flow and Density settings on the adjustment brush. Both of the settings relate to the coverage of “adjustment paint” you get from each brush stroke.
The local adjustment brush allows you to paint specific edits onto areas of your photo. In addition to selecting which edits you paint on, you can also control how that paint is applied.
Flow governs how much paint is laid down per stroke, allowing you to build up to 100%. Say you increase exposure by 1 stop using the adjustment brush. If you set your Flow to 25 (out of 100), each stroke will apply about 25% of your exposure adjustment, or 1/4 stop. You would need to drag your brush over an area at least 4 times to make sure that the 1 stop exposure increase is applied.
Density governs how much paint is laid down per stroke also. However, Density limits the maximum amount that can be applied to a given area, regardless of how many brush strokes you make. Continuing our exposure adjustment example, with the Flow set to 100 and density set to 50, you would never be able to apply more than 1/2 stop of exposure, no matter how many times you dragged your brush over a given area.
Flow is useful in Lightroom when you know that you will need varying degrees of your edit. Rather than creating a new adjustment brush for each edit, you can simply adjust the Flow to match the needs of the area you are painting. For example, say that you need to brighten an area of your image. If the darkest area of your image needs a full stop of additional exposure, but some areas only need a half stop and others only need a quarter stop, you can simply adjust the flow of your brush before painting over each separate area. This is easier than creating three new brushes.
You can see from the photo above that the exposure adjustment gets brighter from 1 to 4. To get the red overlay as a representation of where and how much your painted, type the letter O while your adjustment brush is active. Type O again to turn off this overlay.
Density, in my opinion, is most useful after the fact. Get ready for Cool Tip #1! You’ve increased brightness equally all over one area, only to realize afterwards that you should have varied the paint coverage over that area. For example, in the image above, I painted at 100% Density & Flow to brighten it. After painting, I realized that the brightest part of the face needed only 75% of the brightening amount. I reduced the density of my brush to 75% and painted over the area that was too bright. It’s as if you could subtract 25% of your paint coverage, to bring the total coverage down to 75%. How cool is that?
An added benefit of painting using either Flow or Density, and this is Cool Tip #2, is that you can adjust the overall effect of these adjustments easily. If you carefully painted on your exposure increase and used Density of 100 in some areas, 50 in others, and finished with 25 in the areas needing the least adjustment, and then realized that you brightened them all too much or not enough, you can adjust all 3 areas together. Click on the pin and drag it to the right to increase each area proportionately, or drag it to the left to decrease each area of adjustment.
If you had created 3 separate brushes for this adjustment, you would have to edit each brush individually.
This is rather confusing, right? I think a video is in order for this one. Click here to watch me use the Flow and Density adjustment brush settings in Lightroom on a photo.
The best way to learn how to use Flow and Density to your advantage when making local edits using the Lightroom adjustment brush is to practice. If you still have questions after that, come back and post them in the comments below.