Using the Same Selection for More Than One Adjustment Layer
Sometimes an image has a problem area that requires more than one tweak to make right. You select the area, and create an adjustment layer. Things are looking better. But is there a way to avoid recreating that same selection for the second tweak?
In Photoshop, any active selection becomes a layer mask when you create an adjustment layer. This system works great as it allows you to fine tune the selection after the fact at any point. The adjustment technically applies to the entire layer, but the mask limits its effect to the areas you specify. Modify the selection later, and the adjustment you already made will now apply to more or less of the image based your mask change. This is a key component of non-destructive editing in Photoshop.
But once your selection gets converted into the new layer mask, it's no longer a selection. First the "marching ants" selection border is there, and then it's not. There's no obvious way to create a second adjustment layer with the same selection outline other than to attempt to duplicate that selection yourself. I've seen several photographers do just this — tediously retracing their previous selection as closely as they can.
Instead, there are several much better ways to accomplish this.
First, you can easily recreate your exact selection by using the aptly named "Load Selection..." option on the Select menu. A small dialog box will open given you a list of available sources to load your selection from. You should be able to find the mask for your original adjustment layer in the dropdown list. By default, the "New Selection" option will be selected, but if you already have an active selection you'll have three alternative choices to add the loaded selection to your current one, subtract from it, or intersect the new selection with what you already have. There's also a checkbox to invert the new selection before loading it which can be useful if you want one adjustment layer to affect part of the image, and a second adjustment to affect everything else.
If you're more a fan of mice than menus, you can get at the same thing by right mouse clicking on the icon for an existing layer mask in the layers panel. There is no explicit "Load" choice available on the pop-up context menu, but if you don't currently have a selection, it stands to reason that "Add Mask To Selection" will do what you want. What's odd though is that "Subtract Mask From Selection" does exactly the same thing, as does "Intersect Mask With Selection." So long as you don't currently have an active selection, the three choices are interchangeable.
Either way, once you have your selection back, you can create a new adjustment layer, and the mask on that layer will exactly match that selection. No more need to recreate it freehand.
The drawback to either method of loading a new selection is that once you have that new adjustment layer with the matching mask, it's completely separate from your original mask. Yes, to begin with, it will match the original, but if you change either, that change won't be reflected in the other. The two masks are disconnected.
If you want to keep the mask for both layers in synch, before you create any of your adjustment layers, create a layer group. To do so, click on the icon at the bottom of the layers panel that looks like a file folder. It's in between the new adjustment layer icon (the half-black, half-white circle) and the new layer icon (the one that looks like a sheet of paper). You'll see your new layer group in the layers panel, probably called "Group 1" unless you're just reading this for fun and already knew how to create layer groups.
Next, go ahead and make your selection just as you would if you were about to create your first adjustment layer. To add that selection as a layer mask to the entire group, first make sure your group is the active layer in the layers panel. Then click on the circle-outline-within-a-square icon at the bottom of the layers panel, just to the left of the new adjustment layer icon. This is the new layer mask icon and since your group was active, the mask will now apply to the group as a whole. Any layers added to this group will be masked by this mask.
To add an adjustment layer to the group, make sure the group is active, and then click on the standard half-black, half-white circle icon. You'll see the new adjustment layer underneath your group layer, slightly indented. Just in case you need it, it will still have its own layer mask, but since we want the group mask to control everything in synch, we won't need it here. You can continue adding as many adjustment layers as you need to this group and they will all be masked together by the group mask. And if you need to modify that mask later, it will continue to affect everything in your group in sync.
You may not always need a layer group, but when you do it can be a huge time saver. And even if you don't need it, there's no harm in creating groups anyway, just in case.