6.7. Making Destructive Adjustments on the Layers There are a few adjustments on the Adjustment menu that don't have adjustment layer correspondents. As a result, they are among the more destructive operations that one can perform. However, that doesn't mean you can't use them. You do this by creating a layer on which you can perform destructive editing (this will save space, since you seldom need more than one or two of these for a given image). When you need to do a lot of destructive editing, you'll want to create even more layers using the following method: Drag your Background layer to the New Layer icon at the bottom of the Layers palette. This will duplicate it to the top of the palette. Drag it down to just above the original background layer. Highlight all but the background layer and press Cmd/Ctrl-Opt/Alt-H. A new layer that looks like the background layer with the overall nondestructive adjustments will appear at the top of the stack. Select the top layer and rename it Destructive Edits. Figure 6-35 shows how the Layers palette should look at this stage. Figure 6-35. The Layers palette showing the basic Workflow Layers with the addition of a merged layer that combines all the initial adjustments.
The following are the commands in the Image  Adjustments menu that have no adjustment layer counterpart, along with a description of what each does, and before and after illustrations that show the effect of the adjustment:
Auto Levels The Auto Levels command adjusts each channel individually to the highlight and shadow clipping points that you specify in the Auto Color Options. The white point for each channel is then set to 255. This command sometimes causes surprise color shifts, which you then have to correct using one of the color correction techniques covered earlier in this chapter. Or, you might Undo (Cmd/Ctrl-Z) and try the Auto Contrast command instead.
Auto Contrast This command does the same thing for the RGB channel as the Auto Levels command does for the individual color channels. The effect is to "idealize" the overall image contrast, without affecting color cast.
Auto Color Auto Color arbitrarily and automatically resets the color balance by setting the gray tone at 128 for all three channels. Highlights and shadows are clipped at .5 percent. Figure 6-36 shows the same image "auto-corrected" by Auto Levels, Auto Contrast, and Auto Color. Figure 6-36. The same image, left to right, untouched, the auto-corrected by Auto Levels, Auto Contrast, and Auto Color.
Desaturate This is an automatic command. The result is a crummy black and white image. You're much better off to use the Channel Mixer nondestructively (see the "Channel Mixer" section earlier in this chapter). However, there may be a time when you're in a heck of a hurry. Changing Auto Color Options To change the Auto Color options, which affect all three of the above adjustments, open either the Levels or Curves adjustment layer and click the Options button. You will then see the dialog in Figure 6-37. Figure 6-37. The Auto Color Options dialog. Under Algorithms: Enhance Monochrome Contrast is the equivalent of the Auto Levels command; Enhance Per Channel Contrast is the equivalent of the Auto Contrast command; Find Dark & Light Colors is the equivalent of the Auto Color command. Options for target colors and clipping can also be set. If you check the Save as Defaults checkbox, then when you click Auto in either the Levels or Curves dialog it will perform whichever of the three auto-equivalents you've set it for. Yes! That means that you can perform all three of the above operations nondestructively. You just have to remember to set these options first. |
Match Color Uh, not sure what this command thinks it's doing. It should be called "make a mess of a batch of images for which you're trying to match color." It actually works pretty well if you have a series of images (remember, series means same subject and surroundings) in which lighting conditions change. The trouble arises if there are large areas of very different color, such as a red wall behind one subject and a blue wall behind another. In that case, I prefer to make color adjustments for each image while all the images are open, so that I can compare them directly. More importantly, you can then use adjustment layers and go back and tweak each image until you have a really good match. This can be very important when you're going to use several very different images in the same publication, particularly if they're going to be on the same page or screen.
Replace Color This command brings up the dialog in Figure 6-38. It allows you to replace one fairly solid color in the image with another. It can be a great way to change the color of clothing in a catalog or to change the color of all sorts of things in a fantasy photo taken to illustrate a children's book or a comic book. Click the eyedropper at the top of the dialog to pick the color you want to change. Click the color swatch at the bottom of the dialog and use the Color Picker to pick the color you want to change to or drag the Hue slider until you see the color you want in the swatch. Chances are that you'll only see a change in part of the area you want to recolor. Since you're making this change on a duplicated layer, if you want to further isolate the change, you can erase any color changes you don't want to keep. Figure 6-38. The Replace Color dialog.
Shadow/Highlight This is a command is hard to live without unless you have an assistant and a budget for portable strobes and reflectors. Otherwise, when you're shooting outdoors in sunlight, you will have either blown-out highlights or blown-out shadows. The "Opening Up the Shadows" section in Chapter 7 shows you some nondestructive workarounds to this command. However, this dialog makes corrections fast, easy, and interactive. To keep it nondestructive, create a merged layer at the top of your stack (see instructions at the beginning of this section). Shadow/Highlight is one of the newest commands in Photoshop. It does an excellent job of providing an absolutely shadowless fill-flash, while also allowing you to restore seemingly blocked highlights or tone down images that were too close to a light source. Figure 6-39 shows the before and after imagealong with the dialog that made it so. Figure 6-39. The result of using the Shadow/Highlight command and the associated dialog. You have quite a bit of flexibility with the end result produced with this dialog. There's really nothing mystical about itjust drag the sliders until you get what you like. When the dialog opens, the adjustments you made the last time will still be in effect, so you may not have to make any adjustments at all.
Exposure This adjustment and HDR images are discussed a great deal more in the "Using Photoshop's Merge to HDR Script and the Exposure Command" section in Chapter 11. After all, the Exposure command was really invented for readjusting the appearance of an image after it has undergone a Photoshop CS2 HDR Merge command. These images have a gamma of 1.0, as opposed to the 1.2 gamma typical of an Adobe RGB 1998 image. The HDR images are typically 32-bit images as well, but you can output a 32-bit image from Camera Raw. Exposure will also work with 8- and 16-bit standard images. It just works differently than the other adjustment commands since there are three eyedroppers: White sets the white (brightest) point in the image, Black sets the midtone with which the Offset slider works, and Gray sets the Gamma point for the Gamma slider. Once you've set those points, the dialog has three slider controls:
Exposure Adjusts mostly the brighter half of the tonal scale, although shadow tones may be somewhat affected.
Offset Darkens mostly shadows and midtones.
Gamma Sets the width of the dynamic range for the image. You can get some very strange results from this command. If you're looking for a unique "look" for an image or want to play with black and white results, I suggest you try it. Figure 6-40 shows the dialog; Figure 6-41 shows the original and two different results on a color image. Figure 6-40. The Exposure dialog. Figure 6-41. The image at left is the original interpretation, followed by two separate adjustments.
Equalize Equalize is an automatic command with no settings dialog. It flattens the Histogram, so all levels of brightness are the same intensity. It's especially worth experimenting with in conjunction with the Fade command or the equalized layer's Opacity slider. Furthermore, if you use a nondestructive layer, once you balance the effect by using layer opacity you can erase areas that have been overly affected and end up with some beautiful results. I love the Equalize command for dramatizing existing skies. Figure 6-42 shows an image untouched by Equalize and another in which the image was equalized and then painted back in with the History brush or faded out with the Eraser. Figure 6-42. A duplicate layer in the image at right was Equalized, then the flags and moon were selected, feathered, and erased. Finally, the equalized layer's Opacity was reduced to about 30 percent. The result? A much more interesting sky.
Variations Variations are a visual means of adjusting color balance and exposure. It works only with 8-bit images. When you choose Image Adjust Variations, the dialog shown in Figure 6-43 appears. Be sure to check the Show Clipping box to insure that your choices aren't blocking or oversaturating colors. Drag the Fine Coarse slider to the first notch to the right of Fine to insure that your choices won't overdo it. Then all you hve to do is click the thumbnail(s) that seem to improve your image. Figure 6-43. The Variations dialog. Each time you click a thumbnail, it adds its effect to the Current Pick square. Note that you can change the effect in Shadows, Midtones, or Highlights separately by clicking the radio button for that brightness range. You can also affect the intensity of the saturation of any of the prime colors. Finally, you can change the overall lightness or darkness of the image by clicking the Lighter or Darker thumbnails. When you're happy with what you see, click OK. |
