Today’s Question: Can a linear gradient affect a portion of the picture in the middle of the image? If not, could you achieve the desired effect by applying two linear gradients, one from the top and the other from the bottom?
Tim’s Quick Answer: Yes, it is possible to apply a targeted adjustment in an area defined by a gradient (or pair of gradients) for the central area of an image.
More Detail: A targeted adjustment defined by a linear gradient typically applies an adjustment that affects one side of the image, gradually transitioning to no effect on the opposite side of the image. However, there are ways to have the graduated adjustment affect a central area of an image.
In Photoshop this type of targeted adjustment can be created very easily by using the “Reflected” style for the Gradient tool when creating the gradient on the layer mask for the adjustment layer (or adjustment group). After creating a layer mask (such as by simply adding an adjustment layer) in Photoshop you can select the Gradient tool and set the colors to the defaults of white and black by pressing the letter “D” on the keyboard. You can then choose the fourth of the five style buttons for the gradient on the option bar, which is the Reflected option. Draw a gradient from the center of the image outward, and the resulting mask will be white at the center while tapering off to black in both directions based on the direction you dragged.
If you’re using Lightroom, Lightroom Classic, or Camera Raw, the same type of effect can be achieved by using two gradients to define the overall mask. You could start with a normal Linear Gradient mask, drawing a gradient that goes from the center of the image outward, such as toward the top. This will cause the targeted adjustment to affect the lower portion of the image, tapering off toward the top of the image.
You can then use the Subtract option to apply another Linear Gradient mask, to subtract in this case the bottom portion of the image from the targeted adjustment. For example, you might drag from the bottom edge of the image up toward the middle of the image.
In this scenario, the only area of the image affected by the targeted adjustment would be the central area, tapering based on the gradients both upward and downward. Naturally, the two gradients could be drawn in any direction that makes sense, not just in a vertical line as used in the example above.
