Tools We Don't Use
We've covered most of the tools on the Adjustments submenu, but we've left a few out for the simple reason that we never use them. That said, we feel that a few words of explanation are in order, so here, briefly, are the tools we don't use, and our reasons for avoiding them.
Don't feel that you have to do as we do, or even do as we sayif you find any of the following tools useful, you know something we don't, and you can be proud of your hard-won knowledge. But first take a moment to ponder our critiques in case you are missing something.
The Color Balance command lets you make separate adjustments for red/cyan, green/magenta, and blue/yellow to three arbitrary tonal ranges labelled Highlights, Midtones, and Shadows. The problem is that these ranges overlap, and are never quite where we need them.
Nowadays, color crossovers are relatively raresome early '90s desktop flatbed scanners were rather notorious for producing them, but when we see them now they're usually caused by shooting under mixed lighting, and the required corrections are usually selective rather than global. In any case, we find that it's easier to tweak the color balance of different tonal ranges using Curves.
Go back and read the sidebar, "The Nonlinear Advantage," much earlier in this chapter. If you actually want to blow out your highlights while washing out shadows, or gray your highlights while plugging up shadows, the Brightness slider is the perfect tool. The Contrast slider is likewise great for simultaneously blowing out highlights and plugging up shadows.
We suspect that the only reason that Brightness/Contrast still appears on the Adjustments submenu is that the Photoshop team never removes features (though they did take away the keyboard shortcut a few versions ago). There is simply nothing you can do with Brightness/Contrast that you can't do as easily, with more control, using Levels or Curves.
Match Color sounds like a great idea. We've just never been able to get it to work with any significant degree of reliability. Match Color can produce some interesting creative effects, particularly when you use a source image with a completely different color palette from the one you're adjusting, but the results depend a great deal on any selection you make in the source image, and if you want to tweak that selection, you have to Cancel out of Match Color to do so.
We find that we can create color matches a great deal quicker using either Hue/Saturation or Replace Color. Match Color is just too fickle wand unpredictable for our taste.
Gradient Map is useful for making custom graycale conversions and for creating truly wacky color effects. It's low on our list of grayscale conversion methods because it takes a lot of workyou have to edit the gradient to get the results you want, then use Gradient Map to actually get themand we don't really do wacky color effects, though we have nothing against folks that do.
The Exposure command is really designed for working with HDR (High Dynamic Range) images. On those, it's pretty usefulsee "HDR Imaging" in Chapter 12, Essential Image Techniquesbut on 8-bit or 16-bit/channel images, it doesn't do anything useful that you can't do just as easily with the gray input slider in Levels. Worse, the Exposure and Offset sliders basically replicate the behavior of the Brightness slider in Brightness/Contrast.
Invert, Equalize, Threshold, and Posterize
We often use Invert on masks (when we masked the area we wanted revealed and vice versa), but it's not something we'd ever do to an image. We never use Equalizeit redistributes the tonal values so that the brightest pixels are white, the darkest pixels are black, and the intermedate values are evenly distributed across the tonal range. We've yet to find a use for that, though we try to stay open-minded.
Threshold is useful for turning images into 1-bit black and white bitmaps. We use it when we scan line art, but not as an image correction tool. Posterize does something we generally struggle to avoid!
Variations is a nice tool for learning to distinguish different color casts, but a very blunt instrument indeed for correcting them, and it's limited to 8-bit/channel images. It doesn't do anything that can't be done with a great deal more control and precision using Hue/Saturation. If you're still uncertain of your ability to distinguish a red cast from a magenta one, or a cyan cast from a blue one (and it does take practice), a quick look in Variations can help you make the call, but we don't recommend using it to take whatever remedial action the image needs.