However, I'm a total tease, and FIRST I'm going to tell you about Actions. Actions are another way to apply the same adjustment to multiple layers. It doesn't stay edittable....but it can also do so much more!
Lights, Camera, Actions!
Actions are great when you have repetitive motions you need to go through. Say you need to go through a bunch of files, auto level them, hue/sat them to the exact same value, rotate them 90 degrees clockwise, and resize them to exactly the same size. Actions can try to save our poor carpal tunnely wrists by doing this in one bing bang boom click, once we've done the first one. Actions can record any repeated motion with exactly the same settings, and save that to be applied with one click, regardless of how many steps, at any time.
Firstly here, I'm going to assume throughout this (and, really, all my other) rambling, that your window setup is like mine. There's no real reason for this assumption, other than I think I pretty much keep the default, and you may have to.
You see on the probably right side of your screen (your right, not its right....ok, so I don't think I've mentioned this, but I have a really hard telling my left from my right. So if it's not there, look at the other right, ok?) there are these windows. One of them, possibly the bottom, is where you do your layering magic
If you can't find it, pull down the Windows menu, and choose Actions. If it has a checkmark next to it it's already center stage- if not and you click it, it becomes active, and pops out if you don't have it up already.
There are a couple of folders- Default Actions, possibly Textures. Make a new one, name it "Mine" or "Tralala I can't hear you" or what so ever you please. This is where you will keep your actions so you can find them.
Take your first file, or layer, that you will be applying all these same things to, and make it active. Create a new action in this folder with the same new icon you should be familiar with with Layers. Name it something you can remember, and hit "Record".
Now, do your stuff! Remember, Actions are reeeeeally dumb. They can do exactly the same thing, nothing else. However, they're also kind of smart, you can set your resizing to width by pixels, or percentage, or whatever, and it defines by what it sees set (so you can always scale by 50%, or always 512 wide, or set both height and width to pixels)- it also can apply identical filter settings, or adjustment settings, or pretty much anything really.
Once you're done, hit the stop button, that looks like an old timey cassette tape player stop button. (It's the box.) Now, go to whatever you want to do just like you did....and hit the play button (the filled in arrow), with that Action selected. Sit back and oooooh and aaaaaah over the magic!
You can see everything your action is doing by expanding the arrow next to it, it will show each step with a checkmark next to it. You can toggle steps on and off with these checkmarks, and some expand further to see their settings, what it will apply when the Action is played. Actions will play from the one selected down, if you select one in the middle, skipping the first steps.
Actions are useful in some cases, useless in others. They may or may not be something you want to use. But keep them in mind, for they can save you a lot of hastle, time, and typing, when you do have things you can automate.
But! To get back on the train of thought that got toooootally disrailed there, plowed through a pasture with some cute bunnies, hopped on other tracks and went around a few circles, and finally is reconnecting with what we came here for: Adjustment Layers!
How I Learned to Stop Worrying, and Love the Adjustment Layers
Sorry about that. I get distracted by shiny things, and oh! hey! that's kinda useful crap too! My brain, she is kind of a cluttered mess.
Adjustment Layers are pretty damn superduperawesomefunsauce. They've got a lot of great advantages:
1) They are non destructive. Your original layers are still intact and full of every last drop of juicy information they started with.
2) They are infinitely adjustable. You can go in and tweak that red value 2 degrees up more if you want, you can do a rough "oh, I'll shove everything in that general dirction" and go back and do settings for reals later.
3) They apply to EVERYTHING below them. All layers, without flattening or doing each by hand.
4) They can have masks. You should have learned in our last installment how damn jibbing awesome masks are. This will make you love masks more.
And probably many more, but, eh, that'll do for the sales pitch for now. Once you've used them, you too will squee with delight.
Now, to do: Look to your Layers palette. There are a bunch of wacky icons at the bottom. Mine are chain, squiggly f in a circle, box with a hole in it, circle that's half black/half white diagonally, folder, folded up page, trashcan. In real world terms that translates to:
Link (chain), which links layers so when you move one, you move all, and such things;
Layer Style (f in a circle), which lets you do fancy smacktacular things like drop shadows the easy way, none of this making a selection, filling it with black on a new layer underneath, and blurring it until it looks good like the old days;
Mask (box with a hole), which should you should somewhat understand from our previous installment;
Fill or Adjustment Layer (half black/half white circle, diagonally), which is what we want!;
and New Folder, for putting layers in folders; New Layer, which you should be well versed with; Trash, which you should also be well versed with.
Pull down your half black/half white circle. Pick the type of adjustment, like, say, Hue/Saturation. The normal Hue/Sat thing pops up, move your sliders. Every layer under what you've got selected, including what you've got selected, goes what you choose, like magic! You've got a layer now that's got a wacky sort of control panelly thing instead of a drawing box as its icon, with a drawing box full of white next to it.
If you want to hue shift everything there, we're done. If not though, we have options for applying this selectively. If you want to change your selection by masking, turn to Page 3. If you want to have your adjustment layer apply to cutouts and not a background, turn to Page 5.
Page 3 - Masking for Fun and Profit
You have chosen to play with masking! Masking is a highly rewarding way of dealing with your adjustment layer. You can do things like apply a black to white gradient on your mask to fade the change, or guassian blur selections, make selections off of other layers, or draw what you want directly on your layer. White will show the effect. Black will hide the effect. Draw right on your layer with black and white to change how the effect deals with the layers below it. You can, for instance, make an adjustment layer for shading on clothing, delete it all so it's black, and draw on it with white for the shadows, and this will apply your adjustments. You can easily shade patterns! You can change base layers instead of hue layers on top to change colours of things! And, best of all, you can go back and tweak your shading at any time without messing up your original image- those of you who dodge and burn shade may find that you can get the same effect with adjustment layers without having to start all over when the cat hops up and knocks your mouse arm!
In short: anything you can do to a regular layer, pretty much, can be done to an adjustment layer mask. It will be done entirely in greyscale, and the amount of white in the pixels will determine how much the adjustment shows. Adjustment Layer masks are exactly like layer masks, folder masks, and channels.
For the end blabbering that doesn't really make any difference, turn to Page 8.
Page 5 - You Mean You Kept the Easy Way for Last?
You have chosen the easy way, when you have cutouts! You're smarter than I am, you know, I ALWAYS forget this, and end up selecting and knocking out my selections in the mask the hard way instead.
Put all of the cutouts (basically, but this I mean "anything that isn't a full layer that covers the background and has an alpha") that you want your adjustment layer to apply to in a new folder. You get that with the Folder icon, as if you didn't know already. Now, place (or create) your adjustment layer on top of all of the layers. Still applying to the Background, and you don't want that. But, with one little tiny click...
And that tiny click is you at the top of our Layers palette, there's a dropdown that says "Pass Through". You probably already know about layer modes- if not, they're reeeeally fun. Overlay for highlight layers, for instance. Multiply when you want to make the darks pop. But I digress. Change that from "Pass Through" to "Normal", and now your adjustment layer only applies to things that are "solid"! Magically your background is now happy and free of your adjustment layer, since it isn't in the folder.
For the end blabbering that doesn't really make any difference, turn to Page 8.
Page 8 - The Mostly Unnecessary Conclusion, in which I Blabber Randomly
You're actually going to be happy I didn't illustrate this tutorial at this time. 1) It would have taken me way way longer to do, 2) I would have been illustrating everything with a really badly drawn cartoon of a mantis, and it would have been really bad as I am a totally incapable of using a tablet, as I thought through a lot of this last night as I was trying (and failing) to sleep, as my brain that makes sense decided to try to get a nap, and the other brain that suffers from really bad insomnia makes no sense, ever. Like, WHEEEEEEEEEEEEEEEEE! I'M NAKED! GIMME A CUPCAKE!, but worse. It sometimes involves imaginary critters and going over the same phrases of nonsense over and over like they are the most profound things in the whole wide world.
But anyway. That's adjustment layers! This has only passed on the very slightest and tiniest bit of how awesome they are. This should give you enough of an introduction to find out some of that on your own as you experiment and play with all the amazing things you can do, and enough choice words to drop in a google search for a real proper tutorial, which is how I learn 90% of the stuff I know how to do in Photoshop. Dear Google, I love you. Even when perfectly innocuous search terms drop me into yaoi websites. Or, wait, did I mean especially when?